Add intermediate frame in video buffer

There were only two frames simultaneously:
 - one used by the decoder;
 - one used by the renderer.

When the decoder finished decoding a frame, it swapped it with the
rendering frame.

Adding a third frame provides several benefits:
 - the decoder do not have to wait for the renderer to release the
   mutex;
 - it simplifies the video_buffer API;
 - it makes the rendering frame valid until the next call to
   video_buffer_take_rendering_frame(), which will be useful for
   swscaling on window resize.

app/meson.build

@@ -2,6 +2,7 @@ src = [
     'src/main.c',
     'src/adb.c',
     'src/cli.c',
+    'src/compat.c',
     'src/control_msg.c',
     'src/controller.c',
     'src/decoder.c',
@@ -22,7 +23,8 @@ src = [
     'src/video_buffer.c',
     'src/util/net.c',
     'src/util/process.c',
-    'src/util/str_util.c'
+    'src/util/str_util.c',
+    'src/util/thread.c',
 ]
 
 if host_machine.system() == 'windows'
@@ -31,6 +33,10 @@ else
     src += [ 'src/sys/unix/process.c' ]
 endif
 
+check_functions = [
+    'strdup'
+]
+
 cc = meson.get_compiler('c')
 
 if not get_option('crossbuild_windows')
@@ -86,6 +92,13 @@ endif
 
 conf = configuration_data()
 
+foreach f : check_functions
+  if cc.has_function(f)
+    define = 'HAVE_' + f.underscorify().to_upper()
+    conf.set(define, true)
+  endif
+endforeach
+
 # expose the build type
 conf.set('NDEBUG', get_option('buildtype') != 'debug')
 

app/src/adb.c

@@ -173,7 +173,7 @@ adb_push(const char *serial, const char *local, const char *remote) {
     }
     remote = strquote(remote);
     if (!remote) {
-        SDL_free((void *) local);
+        free((void *) local);
         return PROCESS_NONE;
     }
 #endif
@@ -182,8 +182,8 @@ adb_push(const char *serial, const char *local, const char *remote) {
     process_t proc = adb_execute(serial, adb_cmd, ARRAY_LEN(adb_cmd));
 
 #ifdef __WINDOWS__
-    SDL_free((void *) remote);
+    free((void *) remote);
-    SDL_free((void *) local);
+    free((void *) local);
 #endif
 
     return proc;
@@ -204,7 +204,7 @@ adb_install(const char *serial, const char *local) {
     process_t proc = adb_execute(serial, adb_cmd, ARRAY_LEN(adb_cmd));
 
 #ifdef __WINDOWS__
-    SDL_free((void *) local);
+    free((void *) local);
 #endif
 
     return proc;

app/src/compat.c

@@ -0,0 +1,14 @@
+#include "compat.h"
+
+#include "config.h"
+
+#ifndef HAVE_STRDUP
+char *strdup(const char *s) {
+    size_t size = strlen(s) + 1;
+    char *dup = malloc(size);
+    if (dup) {
+        memcpy(dup, s, size);
+    }
+    return dup;
+}
+#endif

app/src/compat.h

@@ -56,4 +56,8 @@
 # define SCRCPY_SDL_HAS_HINT_VIDEO_X11_NET_WM_BYPASS_COMPOSITOR
 #endif
 
+#ifdef HAVE_STRDUP
+char *strdup(const char *s);
+#endif
+
 #endif

app/src/control_msg.c

@@ -1,6 +1,7 @@
 #include "control_msg.h"
 
 #include <assert.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "util/buffer_util.h"
@@ -93,10 +94,10 @@ void
 control_msg_destroy(struct control_msg *msg) {
     switch (msg->type) {
         case CONTROL_MSG_TYPE_INJECT_TEXT:
-            SDL_free(msg->inject_text.text);
+            free(msg->inject_text.text);
             break;
         case CONTROL_MSG_TYPE_SET_CLIPBOARD:
-            SDL_free(msg->set_clipboard.text);
+            free(msg->set_clipboard.text);
             break;
         default:
             // do nothing

app/src/control_msg.h

@@ -50,7 +50,7 @@ struct control_msg {
             enum android_metastate metastate;
         } inject_keycode;
         struct {
-            char *text; // owned, to be freed by SDL_free()
+            char *text; // owned, to be freed by free()
         } inject_text;
         struct {
             enum android_motionevent_action action;
@@ -65,7 +65,7 @@ struct control_msg {
             int32_t vscroll;
         } inject_scroll_event;
         struct {
-            char *text; // owned, to be freed by SDL_free()
+            char *text; // owned, to be freed by free()
             bool paste;
         } set_clipboard;
         struct {

app/src/controller.c

@@ -2,25 +2,27 @@
 
 #include <assert.h>
 
-#include "util/lock.h"
 #include "util/log.h"
 
 bool
 controller_init(struct controller *controller, socket_t control_socket) {
     cbuf_init(&controller->queue);
 
-    if (!receiver_init(&controller->receiver, control_socket)) {
+    bool ok = receiver_init(&controller->receiver, control_socket);
+    if (!ok) {
         return false;
     }
 
-    if (!(controller->mutex = SDL_CreateMutex())) {
+    ok = sc_mutex_init(&controller->mutex);
+    if (!ok) {
         receiver_destroy(&controller->receiver);
         return false;
     }
 
-    if (!(controller->msg_cond = SDL_CreateCond())) {
+    ok = sc_cond_init(&controller->msg_cond);
+    if (!ok) {
         receiver_destroy(&controller->receiver);
-        SDL_DestroyMutex(controller->mutex);
+        sc_mutex_destroy(&controller->mutex);
         return false;
     }
 
@@ -32,8 +34,8 @@ controller_init(struct controller *controller, socket_t control_socket) {
 
 void
 controller_destroy(struct controller *controller) {
-    SDL_DestroyCond(controller->msg_cond);
+    sc_cond_destroy(&controller->msg_cond);
-    SDL_DestroyMutex(controller->mutex);
+    sc_mutex_destroy(&controller->mutex);
 
     struct control_msg msg;
     while (cbuf_take(&controller->queue, &msg)) {
@@ -46,13 +48,13 @@ controller_destroy(struct controller *controller) {
 bool
 controller_push_msg(struct controller *controller,
                       const struct control_msg *msg) {
-    mutex_lock(controller->mutex);
+    sc_mutex_lock(&controller->mutex);
     bool was_empty = cbuf_is_empty(&controller->queue);
     bool res = cbuf_push(&controller->queue, *msg);
     if (was_empty) {
-        cond_signal(controller->msg_cond);
+        sc_cond_signal(&controller->msg_cond);
     }
-    mutex_unlock(controller->mutex);
+    sc_mutex_unlock(&controller->mutex);
     return res;
 }
 
@@ -73,20 +75,20 @@ run_controller(void *data) {
     struct controller *controller = data;
 
     for (;;) {
-        mutex_lock(controller->mutex);
+        sc_mutex_lock(&controller->mutex);
         while (!controller->stopped && cbuf_is_empty(&controller->queue)) {
-            cond_wait(controller->msg_cond, controller->mutex);
+            sc_cond_wait(&controller->msg_cond, &controller->mutex);
         }
         if (controller->stopped) {
             // stop immediately, do not process further msgs
-            mutex_unlock(controller->mutex);
+            sc_mutex_unlock(&controller->mutex);
             break;
         }
         struct control_msg msg;
         bool non_empty = cbuf_take(&controller->queue, &msg);
         assert(non_empty);
         (void) non_empty;
-        mutex_unlock(controller->mutex);
+        sc_mutex_unlock(&controller->mutex);
 
         bool ok = process_msg(controller, &msg);
         control_msg_destroy(&msg);
@@ -102,16 +104,16 @@ bool
 controller_start(struct controller *controller) {
     LOGD("Starting controller thread");
 
-    controller->thread = SDL_CreateThread(run_controller, "controller",
+    bool ok = sc_thread_create(&controller->thread, run_controller,
-                                          controller);
+                               "controller", controller);
-    if (!controller->thread) {
+    if (!ok) {
         LOGC("Could not start controller thread");
         return false;
     }
 
     if (!receiver_start(&controller->receiver)) {
         controller_stop(controller);
-        SDL_WaitThread(controller->thread, NULL);
+        sc_thread_join(&controller->thread, NULL);
         return false;
     }
 
@@ -120,14 +122,14 @@ controller_start(struct controller *controller) {
 
 void
 controller_stop(struct controller *controller) {
-    mutex_lock(controller->mutex);
+    sc_mutex_lock(&controller->mutex);
     controller->stopped = true;
-    cond_signal(controller->msg_cond);
+    sc_cond_signal(&controller->msg_cond);
-    mutex_unlock(controller->mutex);
+    sc_mutex_unlock(&controller->mutex);
 }
 
 void
 controller_join(struct controller *controller) {
-    SDL_WaitThread(controller->thread, NULL);
+    sc_thread_join(&controller->thread, NULL);
     receiver_join(&controller->receiver);
 }

app/src/controller.h

@@ -4,21 +4,20 @@
 #include "common.h"
 
 #include <stdbool.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 
 #include "control_msg.h"
 #include "receiver.h"
 #include "util/cbuf.h"
 #include "util/net.h"
+#include "util/thread.h"
 
 struct control_msg_queue CBUF(struct control_msg, 64);
 
 struct controller {
     socket_t control_socket;
-    SDL_Thread *thread;
+    sc_thread thread;
-    SDL_mutex *mutex;
+    sc_mutex mutex;
-    SDL_cond *msg_cond;
+    sc_cond msg_cond;
     bool stopped;
     struct control_msg_queue queue;
     struct receiver receiver;

app/src/decoder.c

@@ -3,8 +3,6 @@
 #include <libavformat/avformat.h>
 #include <libavutil/time.h>
 #include <SDL2/SDL_events.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 #include <unistd.h>
 
 #include "events.h"

app/src/device_msg.c

@@ -1,5 +1,6 @@
 #include "device_msg.h"
 
+#include <stdlib.h>
 #include <string.h>
 
 #include "util/buffer_util.h"
@@ -20,7 +21,7 @@ device_msg_deserialize(const unsigned char *buf, size_t len,
             if (clipboard_len > len - 5) {
                 return 0; // not available
             }
-            char *text = SDL_malloc(clipboard_len + 1);
+            char *text = malloc(clipboard_len + 1);
             if (!text) {
                 LOGW("Could not allocate text for clipboard");
                 return -1;
@@ -42,6 +43,6 @@ device_msg_deserialize(const unsigned char *buf, size_t len,
 void
 device_msg_destroy(struct device_msg *msg) {
     if (msg->type == DEVICE_MSG_TYPE_CLIPBOARD) {
-        SDL_free(msg->clipboard.text);
+        free(msg->clipboard.text);
     }
 }

app/src/device_msg.h

@@ -19,7 +19,7 @@ struct device_msg {
     enum device_msg_type type;
     union {
         struct {
-            char *text; // owned, to be freed by SDL_free()
+            char *text; // owned, to be freed by free()
         } clipboard;
     };
 };

app/src/file_handler.c

@@ -4,14 +4,13 @@
 #include <string.h>
 
 #include "adb.h"
-#include "util/lock.h"
 #include "util/log.h"
 
 #define DEFAULT_PUSH_TARGET "/sdcard/"
 
 static void
 file_handler_request_destroy(struct file_handler_request *req) {
-    SDL_free(req->file);
+    free(req->file);
 }
 
 bool
@@ -20,21 +19,23 @@ file_handler_init(struct file_handler *file_handler, const char *serial,
 
     cbuf_init(&file_handler->queue);
 
-    if (!(file_handler->mutex = SDL_CreateMutex())) {
+    bool ok = sc_mutex_init(&file_handler->mutex);
+    if (!ok) {
         return false;
     }
 
-    if (!(file_handler->event_cond = SDL_CreateCond())) {
+    ok = sc_cond_init(&file_handler->event_cond);
-        SDL_DestroyMutex(file_handler->mutex);
+    if (!ok) {
+        sc_mutex_destroy(&file_handler->mutex);
         return false;
     }
 
     if (serial) {
-        file_handler->serial = SDL_strdup(serial);
+        file_handler->serial = strdup(serial);
         if (!file_handler->serial) {
             LOGW("Could not strdup serial");
-            SDL_DestroyCond(file_handler->event_cond);
+            sc_cond_destroy(&file_handler->event_cond);
-            SDL_DestroyMutex(file_handler->mutex);
+            sc_mutex_destroy(&file_handler->mutex);
             return false;
         }
     } else {
@@ -54,9 +55,9 @@ file_handler_init(struct file_handler *file_handler, const char *serial,
 
 void
 file_handler_destroy(struct file_handler *file_handler) {
-    SDL_DestroyCond(file_handler->event_cond);
+    sc_cond_destroy(&file_handler->event_cond);
-    SDL_DestroyMutex(file_handler->mutex);
+    sc_mutex_destroy(&file_handler->mutex);
-    SDL_free(file_handler->serial);
+    free(file_handler->serial);
 
     struct file_handler_request req;
     while (cbuf_take(&file_handler->queue, &req)) {
@@ -92,13 +93,13 @@ file_handler_request(struct file_handler *file_handler,
         .file = file,
     };
 
-    mutex_lock(file_handler->mutex);
+    sc_mutex_lock(&file_handler->mutex);
     bool was_empty = cbuf_is_empty(&file_handler->queue);
     bool res = cbuf_push(&file_handler->queue, req);
     if (was_empty) {
-        cond_signal(file_handler->event_cond);
+        sc_cond_signal(&file_handler->event_cond);
     }
-    mutex_unlock(file_handler->mutex);
+    sc_mutex_unlock(&file_handler->mutex);
     return res;
 }
 
@@ -107,14 +108,14 @@ run_file_handler(void *data) {
     struct file_handler *file_handler = data;
 
     for (;;) {
-        mutex_lock(file_handler->mutex);
+        sc_mutex_lock(&file_handler->mutex);
         file_handler->current_process = PROCESS_NONE;
         while (!file_handler->stopped && cbuf_is_empty(&file_handler->queue)) {
-            cond_wait(file_handler->event_cond, file_handler->mutex);
+            sc_cond_wait(&file_handler->event_cond, &file_handler->mutex);
         }
         if (file_handler->stopped) {
             // stop immediately, do not process further events
-            mutex_unlock(file_handler->mutex);
+            sc_mutex_unlock(&file_handler->mutex);
             break;
         }
         struct file_handler_request req;
@@ -132,7 +133,7 @@ run_file_handler(void *data) {
                                 file_handler->push_target);
         }
         file_handler->current_process = process;
-        mutex_unlock(file_handler->mutex);
+        sc_mutex_unlock(&file_handler->mutex);
 
         if (req.action == ACTION_INSTALL_APK) {
             if (process_check_success(process, "adb install", false)) {
@@ -150,13 +151,13 @@ run_file_handler(void *data) {
             }
         }
 
-        mutex_lock(file_handler->mutex);
+        sc_mutex_lock(&file_handler->mutex);
         // Close the process (it is necessary already terminated)
         // Execute this call with mutex locked to avoid race conditions with
         // file_handler_stop()
         process_close(file_handler->current_process);
         file_handler->current_process = PROCESS_NONE;
-        mutex_unlock(file_handler->mutex);
+        sc_mutex_unlock(&file_handler->mutex);
 
         file_handler_request_destroy(&req);
     }
@@ -167,9 +168,9 @@ bool
 file_handler_start(struct file_handler *file_handler) {
     LOGD("Starting file_handler thread");
 
-    file_handler->thread = SDL_CreateThread(run_file_handler, "file_handler",
+    bool ok = sc_thread_create(&file_handler->thread, run_file_handler,
-                                            file_handler);
+                               "file_handler", file_handler);
-    if (!file_handler->thread) {
+    if (!ok) {
         LOGC("Could not start file_handler thread");
         return false;
     }
@@ -179,18 +180,18 @@ file_handler_start(struct file_handler *file_handler) {
 
 void
 file_handler_stop(struct file_handler *file_handler) {
-    mutex_lock(file_handler->mutex);
+    sc_mutex_lock(&file_handler->mutex);
     file_handler->stopped = true;
-    cond_signal(file_handler->event_cond);
+    sc_cond_signal(&file_handler->event_cond);
     if (file_handler->current_process != PROCESS_NONE) {
         if (!process_terminate(file_handler->current_process)) {
             LOGW("Could not terminate push/install process");
         }
     }
-    mutex_unlock(file_handler->mutex);
+    sc_mutex_unlock(&file_handler->mutex);
 }
 
 void
 file_handler_join(struct file_handler *file_handler) {
-    SDL_WaitThread(file_handler->thread, NULL);
+    sc_thread_join(&file_handler->thread, NULL);
 }

app/src/file_handler.h

@@ -4,11 +4,10 @@
 #include "common.h"
 
 #include <stdbool.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 
 #include "adb.h"
 #include "util/cbuf.h"
+#include "util/thread.h"
 
 typedef enum {
     ACTION_INSTALL_APK,
@@ -25,9 +24,9 @@ struct file_handler_request_queue CBUF(struct file_handler_request, 16);
 struct file_handler {
     char *serial;
     const char *push_target;
-    SDL_Thread *thread;
+    sc_thread thread;
-    SDL_mutex *mutex;
+    sc_mutex mutex;
-    SDL_cond *event_cond;
+    sc_cond event_cond;
     bool stopped;
     bool initialized;
     process_t current_process;
@@ -50,7 +49,7 @@ file_handler_stop(struct file_handler *file_handler);
 void
 file_handler_join(struct file_handler *file_handler);
 
-// take ownership of file, and will SDL_free() it
+// take ownership of file, and will free() it
 bool
 file_handler_request(struct file_handler *file_handler,
                      file_handler_action_t action,

app/src/fps_counter.c

@@ -3,25 +3,24 @@
 #include <assert.h>
 #include <SDL2/SDL_timer.h>
 
-#include "util/lock.h"
 #include "util/log.h"
 
 #define FPS_COUNTER_INTERVAL_MS 1000
 
 bool
 fps_counter_init(struct fps_counter *counter) {
-    counter->mutex = SDL_CreateMutex();
+    bool ok = sc_mutex_init(&counter->mutex);
-    if (!counter->mutex) {
+    if (!ok) {
         return false;
     }
 
-    counter->state_cond = SDL_CreateCond();
+    ok = sc_cond_init(&counter->state_cond);
-    if (!counter->state_cond) {
+    if (!ok) {
-        SDL_DestroyMutex(counter->mutex);
+        sc_mutex_destroy(&counter->mutex);
         return false;
     }
 
-    counter->thread = NULL;
+    counter->thread_started = false;
     atomic_init(&counter->started, 0);
     // no need to initialize the other fields, they are unused until started
 
@@ -30,8 +29,8 @@ fps_counter_init(struct fps_counter *counter) {
 
 void
 fps_counter_destroy(struct fps_counter *counter) {
-    SDL_DestroyCond(counter->state_cond);
+    sc_cond_destroy(&counter->state_cond);
-    SDL_DestroyMutex(counter->mutex);
+    sc_mutex_destroy(&counter->mutex);
 }
 
 static inline bool
@@ -77,10 +76,10 @@ static int
 run_fps_counter(void *data) {
     struct fps_counter *counter = data;
 
-    mutex_lock(counter->mutex);
+    sc_mutex_lock(&counter->mutex);
     while (!counter->interrupted) {
         while (!counter->interrupted && !is_started(counter)) {
-            cond_wait(counter->state_cond, counter->mutex);
+            sc_cond_wait(&counter->state_cond, &counter->mutex);
         }
         while (!counter->interrupted && is_started(counter)) {
             uint32_t now = SDL_GetTicks();
@@ -90,32 +89,35 @@ run_fps_counter(void *data) {
             uint32_t remaining = counter->next_timestamp - now;
 
             // ignore the reason (timeout or signaled), we just loop anyway
-            cond_wait_timeout(counter->state_cond, counter->mutex, remaining);
+            sc_cond_timedwait(&counter->state_cond, &counter->mutex, remaining);
         }
     }
-    mutex_unlock(counter->mutex);
+    sc_mutex_unlock(&counter->mutex);
     return 0;
 }
 
 bool
 fps_counter_start(struct fps_counter *counter) {
-    mutex_lock(counter->mutex);
+    sc_mutex_lock(&counter->mutex);
     counter->next_timestamp = SDL_GetTicks() + FPS_COUNTER_INTERVAL_MS;
     counter->nr_rendered = 0;
     counter->nr_skipped = 0;
-    mutex_unlock(counter->mutex);
+    sc_mutex_unlock(&counter->mutex);
 
     set_started(counter, true);
-    cond_signal(counter->state_cond);
+    sc_cond_signal(&counter->state_cond);
 
-    // counter->thread is always accessed from the same thread, no need to lock
+    // counter->thread_started and counter->thread are always accessed from the
-    if (!counter->thread) {
+    // same thread, no need to lock
-        counter->thread =
+    if (!counter->thread_started) {
-            SDL_CreateThread(run_fps_counter, "fps counter", counter);
+        bool ok = sc_thread_create(&counter->thread, run_fps_counter,
-        if (!counter->thread) {
+                                   "fps counter", counter);
+        if (!ok) {
             LOGE("Could not start FPS counter thread");
             return false;
         }
+
+        counter->thread_started = true;
     }
 
     return true;
@@ -124,7 +126,7 @@ fps_counter_start(struct fps_counter *counter) {
 void
 fps_counter_stop(struct fps_counter *counter) {
     set_started(counter, false);
-    cond_signal(counter->state_cond);
+    sc_cond_signal(&counter->state_cond);
 }
 
 bool
@@ -134,21 +136,21 @@ fps_counter_is_started(struct fps_counter *counter) {
 
 void
 fps_counter_interrupt(struct fps_counter *counter) {
-    if (!counter->thread) {
+    if (!counter->thread_started) {
         return;
     }
 
-    mutex_lock(counter->mutex);
+    sc_mutex_lock(&counter->mutex);
     counter->interrupted = true;
-    mutex_unlock(counter->mutex);
+    sc_mutex_unlock(&counter->mutex);
     // wake up blocking wait
-    cond_signal(counter->state_cond);
+    sc_cond_signal(&counter->state_cond);
 }
 
 void
 fps_counter_join(struct fps_counter *counter) {
-    if (counter->thread) {
+    if (counter->thread_started) {
-        SDL_WaitThread(counter->thread, NULL);
+        sc_thread_join(&counter->thread, NULL);
     }
 }
 
@@ -158,11 +160,11 @@ fps_counter_add_rendered_frame(struct fps_counter *counter) {
         return;
     }
 
-    mutex_lock(counter->mutex);
+    sc_mutex_lock(&counter->mutex);
     uint32_t now = SDL_GetTicks();
     check_interval_expired(counter, now);
     ++counter->nr_rendered;
-    mutex_unlock(counter->mutex);
+    sc_mutex_unlock(&counter->mutex);
 }
 
 void
@@ -171,9 +173,9 @@ fps_counter_add_skipped_frame(struct fps_counter *counter) {
         return;
     }
 
-    mutex_lock(counter->mutex);
+    sc_mutex_lock(&counter->mutex);
     uint32_t now = SDL_GetTicks();
     check_interval_expired(counter, now);
     ++counter->nr_skipped;
-    mutex_unlock(counter->mutex);
+    sc_mutex_unlock(&counter->mutex);
 }

app/src/fps_counter.h

@@ -6,13 +6,15 @@
 #include <stdatomic.h>
 #include <stdbool.h>
 #include <stdint.h>
-#include <SDL2/SDL_mutex.h>
+
-#include <SDL2/SDL_thread.h>
+#include "util/thread.h"
 
 struct fps_counter {
-    SDL_Thread *thread;
+    sc_thread thread;
-    SDL_mutex *mutex;
+    sc_mutex mutex;
-    SDL_cond *state_cond;
+    sc_cond state_cond;
+
+    bool thread_started;
 
     // atomic so that we can check without locking the mutex
     // if the FPS counter is disabled, we don't want to lock unnecessarily

app/src/input_manager.c

@@ -4,7 +4,6 @@
 #include <SDL2/SDL_keycode.h>
 
 #include "event_converter.h"
-#include "util/lock.h"
 #include "util/log.h"
 
 static const int ACTION_DOWN = 1;
@@ -190,13 +189,20 @@ set_device_clipboard(struct controller *controller, bool paste) {
         return;
     }
 
+    char *text_dup = strdup(text);
+    SDL_free(text);
+    if (!text_dup) {
+        LOGW("Could not strdup input text");
+        return;
+    }
+
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_SET_CLIPBOARD;
-    msg.set_clipboard.text = text;
+    msg.set_clipboard.text = text_dup;
     msg.set_clipboard.paste = paste;
 
     if (!controller_push_msg(controller, &msg)) {
-        SDL_free(text);
+        free(text_dup);
         LOGW("Could not request 'set device clipboard'");
     }
 }
@@ -242,11 +248,18 @@ clipboard_paste(struct controller *controller) {
         return;
     }
 
+    char *text_dup = strdup(text);
+    SDL_free(text);
+    if (!text_dup) {
+        LOGW("Could not strdup input text");
+        return;
+    }
+
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_INJECT_TEXT;
-    msg.inject_text.text = text;
+    msg.inject_text.text = text_dup;
     if (!controller_push_msg(controller, &msg)) {
-        SDL_free(text);
+        free(text_dup);
         LOGW("Could not request 'paste clipboard'");
     }
 }
@@ -291,13 +304,13 @@ input_manager_process_text_input(struct input_manager *im,
 
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_INJECT_TEXT;
-    msg.inject_text.text = SDL_strdup(event->text);
+    msg.inject_text.text = strdup(event->text);
     if (!msg.inject_text.text) {
         LOGW("Could not strdup input text");
         return;
     }
     if (!controller_push_msg(im->controller, &msg)) {
-        SDL_free(msg.inject_text.text);
+        free(msg.inject_text.text);
         LOGW("Could not request 'inject text'");
     }
 }

app/src/receiver.c

@@ -4,12 +4,12 @@
 #include <SDL2/SDL_clipboard.h>
 
 #include "device_msg.h"
-#include "util/lock.h"
 #include "util/log.h"
 
 bool
 receiver_init(struct receiver *receiver, socket_t control_socket) {
-    if (!(receiver->mutex = SDL_CreateMutex())) {
+    bool ok = sc_mutex_init(&receiver->mutex);
+    if (!ok) {
         return false;
     }
     receiver->control_socket = control_socket;
@@ -18,7 +18,7 @@ receiver_init(struct receiver *receiver, socket_t control_socket) {
 
 void
 receiver_destroy(struct receiver *receiver) {
-    SDL_DestroyMutex(receiver->mutex);
+    sc_mutex_destroy(&receiver->mutex);
 }
 
 static void
@@ -101,8 +101,9 @@ bool
 receiver_start(struct receiver *receiver) {
     LOGD("Starting receiver thread");
 
-    receiver->thread = SDL_CreateThread(run_receiver, "receiver", receiver);
+    bool ok = sc_thread_create(&receiver->thread, run_receiver, "receiver",
-    if (!receiver->thread) {
+                               receiver);
+    if (!ok) {
         LOGC("Could not start receiver thread");
         return false;
     }
@@ -112,5 +113,5 @@ receiver_start(struct receiver *receiver) {
 
 void
 receiver_join(struct receiver *receiver) {
-    SDL_WaitThread(receiver->thread, NULL);
+    sc_thread_join(&receiver->thread, NULL);
 }

app/src/receiver.h

@@ -4,17 +4,16 @@
 #include "common.h"
 
 #include <stdbool.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 
 #include "util/net.h"
+#include "util/thread.h"
 
 // receive events from the device
 // managed by the controller
 struct receiver {
     socket_t control_socket;
-    SDL_Thread *thread;
+    sc_thread thread;
-    SDL_mutex *mutex;
+    sc_mutex mutex;
 };
 
 bool

app/src/recorder.c

@@ -3,7 +3,6 @@
 #include <assert.h>
 #include <libavutil/time.h>
 
-#include "util/lock.h"
 #include "util/log.h"
 
 static const AVRational SCRCPY_TIME_BASE = {1, 1000000}; // timestamps in us
@@ -27,7 +26,7 @@ find_muxer(const char *name) {
 
 static struct record_packet *
 record_packet_new(const AVPacket *packet) {
-    struct record_packet *rec = SDL_malloc(sizeof(*rec));
+    struct record_packet *rec = malloc(sizeof(*rec));
     if (!rec) {
         return NULL;
     }
@@ -37,7 +36,7 @@ record_packet_new(const AVPacket *packet) {
     av_init_packet(&rec->packet);
 
     if (av_packet_ref(&rec->packet, packet)) {
-        SDL_free(rec);
+        free(rec);
         return NULL;
     }
     return rec;
@@ -46,7 +45,7 @@ record_packet_new(const AVPacket *packet) {
 static void
 record_packet_delete(struct record_packet *rec) {
     av_packet_unref(&rec->packet);
-    SDL_free(rec);
+    free(rec);
 }
 
 static void
@@ -63,24 +62,24 @@ recorder_init(struct recorder *recorder,
               const char *filename,
               enum sc_record_format format,
               struct size declared_frame_size) {
-    recorder->filename = SDL_strdup(filename);
+    recorder->filename = strdup(filename);
     if (!recorder->filename) {
         LOGE("Could not strdup filename");
         return false;
     }
 
-    recorder->mutex = SDL_CreateMutex();
+    bool ok = sc_mutex_init(&recorder->mutex);
-    if (!recorder->mutex) {
+    if (!ok) {
         LOGC("Could not create mutex");
-        SDL_free(recorder->filename);
+        free(recorder->filename);
         return false;
     }
 
-    recorder->queue_cond = SDL_CreateCond();
+    ok = sc_cond_init(&recorder->queue_cond);
-    if (!recorder->queue_cond) {
+    if (!ok) {
         LOGC("Could not create cond");
-        SDL_DestroyMutex(recorder->mutex);
+        sc_mutex_destroy(&recorder->mutex);
-        SDL_free(recorder->filename);
+        free(recorder->filename);
         return false;
     }
 
@@ -97,9 +96,9 @@ recorder_init(struct recorder *recorder,
 
 void
 recorder_destroy(struct recorder *recorder) {
-    SDL_DestroyCond(recorder->queue_cond);
+    sc_cond_destroy(&recorder->queue_cond);
-    SDL_DestroyMutex(recorder->mutex);
+    sc_mutex_destroy(&recorder->mutex);
-    SDL_free(recorder->filename);
+    free(recorder->filename);
 }
 
 static const char *
@@ -258,17 +257,17 @@ run_recorder(void *data) {
     struct recorder *recorder = data;
 
     for (;;) {
-        mutex_lock(recorder->mutex);
+        sc_mutex_lock(&recorder->mutex);
 
         while (!recorder->stopped && queue_is_empty(&recorder->queue)) {
-            cond_wait(recorder->queue_cond, recorder->mutex);
+            sc_cond_wait(&recorder->queue_cond, &recorder->mutex);
         }
 
         // if stopped is set, continue to process the remaining events (to
         // finish the recording) before actually stopping
 
         if (recorder->stopped && queue_is_empty(&recorder->queue)) {
-            mutex_unlock(recorder->mutex);
+            sc_mutex_unlock(&recorder->mutex);
             struct record_packet *last = recorder->previous;
             if (last) {
                 // assign an arbitrary duration to the last packet
@@ -288,7 +287,7 @@ run_recorder(void *data) {
         struct record_packet *rec;
         queue_take(&recorder->queue, next, &rec);
 
-        mutex_unlock(recorder->mutex);
+        sc_mutex_unlock(&recorder->mutex);
 
         // recorder->previous is only written from this thread, no need to lock
         struct record_packet *previous = recorder->previous;
@@ -311,11 +310,11 @@ run_recorder(void *data) {
         if (!ok) {
             LOGE("Could not record packet");
 
-            mutex_lock(recorder->mutex);
+            sc_mutex_lock(&recorder->mutex);
             recorder->failed = true;
             // discard pending packets
             recorder_queue_clear(&recorder->queue);
-            mutex_unlock(recorder->mutex);
+            sc_mutex_unlock(&recorder->mutex);
             break;
         }
 
@@ -330,8 +329,9 @@ bool
 recorder_start(struct recorder *recorder) {
     LOGD("Starting recorder thread");
 
-    recorder->thread = SDL_CreateThread(run_recorder, "recorder", recorder);
+    bool ok = sc_thread_create(&recorder->thread, run_recorder, "recorder",
-    if (!recorder->thread) {
+                               recorder);
+    if (!ok) {
         LOGC("Could not start recorder thread");
         return false;
     }
@@ -341,38 +341,38 @@ recorder_start(struct recorder *recorder) {
 
 void
 recorder_stop(struct recorder *recorder) {
-    mutex_lock(recorder->mutex);
+    sc_mutex_lock(&recorder->mutex);
     recorder->stopped = true;
-    cond_signal(recorder->queue_cond);
+    sc_cond_signal(&recorder->queue_cond);
-    mutex_unlock(recorder->mutex);
+    sc_mutex_unlock(&recorder->mutex);
 }
 
 void
 recorder_join(struct recorder *recorder) {
-    SDL_WaitThread(recorder->thread, NULL);
+    sc_thread_join(&recorder->thread, NULL);
 }
 
 bool
 recorder_push(struct recorder *recorder, const AVPacket *packet) {
-    mutex_lock(recorder->mutex);
+    sc_mutex_lock(&recorder->mutex);
     assert(!recorder->stopped);
 
     if (recorder->failed) {
         // reject any new packet (this will stop the stream)
-        mutex_unlock(recorder->mutex);
+        sc_mutex_unlock(&recorder->mutex);
         return false;
     }
 
     struct record_packet *rec = record_packet_new(packet);
     if (!rec) {
         LOGC("Could not allocate record packet");
-        mutex_unlock(recorder->mutex);
+        sc_mutex_unlock(&recorder->mutex);
         return false;
     }
 
     queue_push(&recorder->queue, next, rec);
-    cond_signal(recorder->queue_cond);
+    sc_cond_signal(&recorder->queue_cond);
 
-    mutex_unlock(recorder->mutex);
+    sc_mutex_unlock(&recorder->mutex);
     return true;
 }

app/src/recorder.h

@@ -5,12 +5,11 @@
 
 #include <stdbool.h>
 #include <libavformat/avformat.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 
 #include "coords.h"
 #include "scrcpy.h"
 #include "util/queue.h"
+#include "util/thread.h"
 
 struct record_packet {
     AVPacket packet;
@@ -26,9 +25,9 @@ struct recorder {
     struct size declared_frame_size;
     bool header_written;
 
-    SDL_Thread *thread;
+    sc_thread thread;
-    SDL_mutex *mutex;
+    sc_mutex mutex;
-    SDL_cond *queue_cond;
+    sc_cond queue_cond;
     bool stopped; // set on recorder_stop() by the stream reader
     bool failed; // set on packet write failure
     struct recorder_queue queue;

app/src/scrcpy.c

@@ -26,7 +26,6 @@
 #include "stream.h"
 #include "tiny_xpm.h"
 #include "video_buffer.h"
-#include "util/lock.h"
 #include "util/log.h"
 #include "util/net.h"
 
@@ -226,13 +225,20 @@ handle_event(SDL_Event *event, const struct scrcpy_options *options) {
             if (!options->control) {
                 break;
             }
+            char *file = strdup(event->drop.file);
+            SDL_free(event->drop.file);
+            if (!file) {
+                LOGW("Could not strdup drop filename\n");
+                break;
+            }
+
             file_handler_action_t action;
-            if (is_apk(event->drop.file)) {
+            if (is_apk(file)) {
                 action = ACTION_INSTALL_APK;
             } else {
                 action = ACTION_PUSH_FILE;
             }
-            file_handler_request(&file_handler, action, event->drop.file);
+            file_handler_request(&file_handler, action, file);
             break;
         }
     }
@@ -286,7 +292,7 @@ av_log_callback(void *avcl, int level, const char *fmt, va_list vl) {
     if (priority == 0) {
         return;
     }
-    char *local_fmt = SDL_malloc(strlen(fmt) + 10);
+    char *local_fmt = malloc(strlen(fmt) + 10);
     if (!local_fmt) {
         LOGC("Could not allocate string");
         return;
@@ -295,7 +301,7 @@ av_log_callback(void *avcl, int level, const char *fmt, va_list vl) {
     strcpy(local_fmt, "[FFmpeg] ");
     strcpy(local_fmt + 9, fmt);
     SDL_LogMessageV(SDL_LOG_CATEGORY_VIDEO, priority, local_fmt, vl);
-    SDL_free(local_fmt);
+    free(local_fmt);
 }
 
 bool

app/src/screen.c

@@ -8,7 +8,6 @@
 #include "scrcpy.h"
 #include "tiny_xpm.h"
 #include "video_buffer.h"
-#include "util/lock.h"
 #include "util/log.h"
 
 #define DISPLAY_MARGINS 96
@@ -454,15 +453,13 @@ update_texture(struct screen *screen, const AVFrame *frame) {
 
 bool
 screen_update_frame(struct screen *screen, struct video_buffer *vb) {
-    mutex_lock(vb->mutex);
+    const AVFrame *frame = video_buffer_take_rendering_frame(vb);
-    const AVFrame *frame = video_buffer_consume_rendered_frame(vb);
     struct size new_frame_size = {frame->width, frame->height};
     if (!prepare_for_frame(screen, new_frame_size)) {
-        mutex_unlock(vb->mutex);
+        sc_mutex_unlock(&vb->mutex);
         return false;
     }
     update_texture(screen, frame);
-    mutex_unlock(vb->mutex);
 
     screen_render(screen, false);
     return true;

app/src/server.c

@@ -5,12 +5,10 @@
 #include <inttypes.h>
 #include <libgen.h>
 #include <stdio.h>
-#include <SDL2/SDL_thread.h>
 #include <SDL2/SDL_timer.h>
 #include <SDL2/SDL_platform.h>
 
 #include "adb.h"
-#include "util/lock.h"
 #include "util/log.h"
 #include "util/net.h"
 #include "util/str_util.h"
@@ -33,7 +31,7 @@ get_server_path(void) {
 #ifdef __WINDOWS__
         char *server_path = utf8_from_wide_char(server_path_env);
 #else
-        char *server_path = SDL_strdup(server_path_env);
+        char *server_path = strdup(server_path_env);
 #endif
         if (!server_path) {
             LOGE("Could not allocate memory");
@@ -45,7 +43,7 @@ get_server_path(void) {
 
 #ifndef PORTABLE
     LOGD("Using server: " DEFAULT_SERVER_PATH);
-    char *server_path = SDL_strdup(DEFAULT_SERVER_PATH);
+    char *server_path = strdup(DEFAULT_SERVER_PATH);
     if (!server_path) {
         LOGE("Could not allocate memory");
         return NULL;
@@ -67,11 +65,11 @@ get_server_path(void) {
 
     // sizeof(SERVER_FILENAME) gives statically the size including the null byte
     size_t len = dirlen + 1 + sizeof(SERVER_FILENAME);
-    char *server_path = SDL_malloc(len);
+    char *server_path = malloc(len);
     if (!server_path) {
         LOGE("Could not alloc server path string, "
              "using " SERVER_FILENAME " from current directory");
-        SDL_free(executable_path);
+        free(executable_path);
         return SERVER_FILENAME;
     }
 
@@ -80,7 +78,7 @@ get_server_path(void) {
     memcpy(&server_path[dirlen + 1], SERVER_FILENAME, sizeof(SERVER_FILENAME));
     // the final null byte has been copied with SERVER_FILENAME
 
-    SDL_free(executable_path);
+    free(executable_path);
 
     LOGD("Using server (portable): %s", server_path);
     return server_path;
@@ -95,11 +93,11 @@ push_server(const char *serial) {
     }
     if (!is_regular_file(server_path)) {
         LOGE("'%s' does not exist or is not a regular file\n", server_path);
-        SDL_free(server_path);
+        free(server_path);
         return false;
     }
     process_t process = adb_push(serial, server_path, DEVICE_SERVER_PATH);
-    SDL_free(server_path);
+    free(server_path);
     return process_check_success(process, "adb push", true);
 }
 
@@ -357,18 +355,17 @@ bool
 server_init(struct server *server) {
     server->serial = NULL;
     server->process = PROCESS_NONE;
-    server->wait_server_thread = NULL;
     atomic_flag_clear_explicit(&server->server_socket_closed,
                                memory_order_relaxed);
 
-    server->mutex = SDL_CreateMutex();
+    bool ok = sc_mutex_init(&server->mutex);
-    if (!server->mutex) {
+    if (!ok) {
         return false;
     }
 
-    server->process_terminated_cond = SDL_CreateCond();
+    ok = sc_cond_init(&server->process_terminated_cond);
-    if (!server->process_terminated_cond) {
+    if (!ok) {
-        SDL_DestroyMutex(server->mutex);
+        sc_mutex_destroy(&server->mutex);
         return false;
     }
 
@@ -393,10 +390,10 @@ run_wait_server(void *data) {
     struct server *server = data;
     process_wait(server->process, false); // ignore exit code
 
-    mutex_lock(server->mutex);
+    sc_mutex_lock(&server->mutex);
     server->process_terminated = true;
-    cond_signal(server->process_terminated_cond);
+    sc_cond_signal(&server->process_terminated_cond);
-    mutex_unlock(server->mutex);
+    sc_mutex_unlock(&server->mutex);
 
     // no need for synchronization, server_socket is initialized before this
     // thread was created
@@ -416,7 +413,7 @@ server_start(struct server *server, const char *serial,
     server->port_range = params->port_range;
 
     if (serial) {
-        server->serial = SDL_strdup(serial);
+        server->serial = strdup(serial);
         if (!server->serial) {
             return false;
         }
@@ -443,9 +440,9 @@ server_start(struct server *server, const char *serial,
     // things simple and multiplatform, just spawn a new thread waiting for the
     // server process and calling shutdown()/close() on the server socket if
     // necessary to wake up any accept() blocking call.
-    server->wait_server_thread =
+    bool ok = sc_thread_create(&server->wait_server_thread, run_wait_server,
-        SDL_CreateThread(run_wait_server, "wait-server", server);
+                               "wait-server", server);
-    if (!server->wait_server_thread) {
+    if (!ok) {
         process_terminate(server->process);
         process_wait(server->process, true); // ignore exit code
         goto error2;
@@ -466,7 +463,7 @@ error2:
     }
     disable_tunnel(server);
 error1:
-    SDL_free(server->serial);
+    free(server->serial);
     return false;
 }
 
@@ -535,33 +532,33 @@ server_stop(struct server *server) {
     }
 
     // Give some delay for the server to terminate properly
-    mutex_lock(server->mutex);
+    sc_mutex_lock(&server->mutex);
-    int r = 0;
+    bool signaled = false;
     if (!server->process_terminated) {
 #define WATCHDOG_DELAY_MS 1000
-        r = cond_wait_timeout(server->process_terminated_cond,
+        signaled = sc_cond_timedwait(&server->process_terminated_cond,
-                              server->mutex,
+                                     &server->mutex,
-                              WATCHDOG_DELAY_MS);
+                                     WATCHDOG_DELAY_MS);
     }
-    mutex_unlock(server->mutex);
+    sc_mutex_unlock(&server->mutex);
 
     // After this delay, kill the server if it's not dead already.
     // On some devices, closing the sockets is not sufficient to wake up the
     // blocking calls while the device is asleep.
-    if (r == SDL_MUTEX_TIMEDOUT) {
+    if (!signaled) {
         // The process is terminated, but not reaped (closed) yet, so its PID
         // is still valid.
         LOGW("Killing the server...");
         process_terminate(server->process);
     }
 
-    SDL_WaitThread(server->wait_server_thread, NULL);
+    sc_thread_join(&server->wait_server_thread, NULL);
     process_close(server->process);
 }
 
 void
 server_destroy(struct server *server) {
-    SDL_free(server->serial);
+    free(server->serial);
-    SDL_DestroyCond(server->process_terminated_cond);
+    sc_cond_destroy(&server->process_terminated_cond);
-    SDL_DestroyMutex(server->mutex);
+    sc_mutex_destroy(&server->mutex);
 }

app/src/server.h

@@ -6,21 +6,21 @@
 #include <stdatomic.h>
 #include <stdbool.h>
 #include <stdint.h>
-#include <SDL2/SDL_thread.h>
 
 #include "adb.h"
 #include "scrcpy.h"
 #include "util/log.h"
 #include "util/net.h"
+#include "util/thread.h"
 
 struct server {
     char *serial;
     process_t process;
-    SDL_Thread *wait_server_thread;
+    sc_thread wait_server_thread;
     atomic_flag server_socket_closed;
 
-    SDL_mutex *mutex;
+    sc_mutex mutex;
-    SDL_cond *process_terminated_cond;
+    sc_cond process_terminated_cond;
     bool process_terminated;
 
     socket_t server_socket; // only used if !tunnel_forward

app/src/stream.c

@@ -4,8 +4,6 @@
 #include <libavformat/avformat.h>
 #include <libavutil/time.h>
 #include <SDL2/SDL_events.h>
-#include <SDL2/SDL_mutex.h>
-#include <SDL2/SDL_thread.h>
 #include <unistd.h>
 
 #include "decoder.h"
@@ -279,8 +277,8 @@ bool
 stream_start(struct stream *stream) {
     LOGD("Starting stream thread");
 
-    stream->thread = SDL_CreateThread(run_stream, "stream", stream);
+    bool ok = sc_thread_create(&stream->thread, run_stream, "stream", stream);
-    if (!stream->thread) {
+    if (!ok) {
         LOGC("Could not start stream thread");
         return false;
     }
@@ -296,5 +294,5 @@ stream_stop(struct stream *stream) {
 
 void
 stream_join(struct stream *stream) {
-    SDL_WaitThread(stream->thread, NULL);
+    sc_thread_join(&stream->thread, NULL);
 }

app/src/stream.h

@@ -7,15 +7,15 @@
 #include <stdint.h>
 #include <libavformat/avformat.h>
 #include <SDL2/SDL_atomic.h>
-#include <SDL2/SDL_thread.h>
 
 #include "util/net.h"
+#include "util/thread.h"
 
 struct video_buffer;
 
 struct stream {
     socket_t socket;
-    SDL_Thread *thread;
+    sc_thread thread;
     struct decoder *decoder;
     struct recorder *recorder;
     AVCodecContext *codec_ctx;

app/src/sys/unix/process.c

@@ -156,7 +156,7 @@ get_executable_path(void) {
         return NULL;
     }
     buf[len] = '\0';
-    return SDL_strdup(buf);
+    return strdup(buf);
 #else
     // in practice, we only need this feature for portable builds, only used on
     // Windows, so we don't care implementing it for every platform

app/src/sys/win/process.c

@@ -41,7 +41,7 @@ process_execute(const char *const argv[], HANDLE *handle) {
 
     if (!CreateProcessW(NULL, wide, NULL, NULL, FALSE, 0, NULL, NULL, &si,
                         &pi)) {
-        SDL_free(wide);
+        free(wide);
         *handle = NULL;
         if (GetLastError() == ERROR_FILE_NOT_FOUND) {
             return PROCESS_ERROR_MISSING_BINARY;
@@ -49,7 +49,7 @@ process_execute(const char *const argv[], HANDLE *handle) {
         return PROCESS_ERROR_GENERIC;
     }
 
-    SDL_free(wide);
+    free(wide);
     *handle = pi.hProcess;
     return PROCESS_SUCCESS;
 }
@@ -105,7 +105,7 @@ is_regular_file(const char *path) {
 
     struct _stat path_stat;
     int r = _wstat(wide_path, &path_stat);
-    SDL_free(wide_path);
+    free(wide_path);
 
     if (r) {
         perror("stat");

app/src/util/lock.h

@@ -1,75 +0,0 @@
-#ifndef LOCK_H
-#define LOCK_H
-
-#include "common.h"
-
-#include <stdint.h>
-#include <SDL2/SDL_mutex.h>
-
-#include "log.h"
-
-static inline void
-mutex_lock(SDL_mutex *mutex) {
-    int r = SDL_LockMutex(mutex);
-#ifndef NDEBUG
-    if (r) {
-        LOGC("Could not lock mutex: %s", SDL_GetError());
-        abort();
-    }
-#else
-    (void) r;
-#endif
-}
-
-static inline void
-mutex_unlock(SDL_mutex *mutex) {
-    int r = SDL_UnlockMutex(mutex);
-#ifndef NDEBUG
-    if (r) {
-        LOGC("Could not unlock mutex: %s", SDL_GetError());
-        abort();
-    }
-#else
-    (void) r;
-#endif
-}
-
-static inline void
-cond_wait(SDL_cond *cond, SDL_mutex *mutex) {
-    int r = SDL_CondWait(cond, mutex);
-#ifndef NDEBUG
-    if (r) {
-        LOGC("Could not wait on condition: %s", SDL_GetError());
-        abort();
-    }
-#else
-    (void) r;
-#endif
-}
-
-static inline int
-cond_wait_timeout(SDL_cond *cond, SDL_mutex *mutex, uint32_t ms) {
-    int r = SDL_CondWaitTimeout(cond, mutex, ms);
-#ifndef NDEBUG
-    if (r < 0) {
-        LOGC("Could not wait on condition with timeout: %s", SDL_GetError());
-        abort();
-    }
-#endif
-    return r;
-}
-
-static inline void
-cond_signal(SDL_cond *cond) {
-    int r = SDL_CondSignal(cond);
-#ifndef NDEBUG
-    if (r) {
-        LOGC("Could not signal a condition: %s", SDL_GetError());
-        abort();
-    }
-#else
-    (void) r;
-#endif
-}
-
-#endif

app/src/util/process.h

@@ -70,7 +70,7 @@ search_executable(const char *file);
 #endif
 
 // return the absolute path of the executable (the scrcpy binary)
-// may be NULL on error; to be freed by SDL_free
+// may be NULL on error; to be freed by free()
 char *
 get_executable_path(void);
 

app/src/util/str_util.c

@@ -10,8 +10,6 @@
 # include <tchar.h>
 #endif
 
-#include <SDL2/SDL_stdinc.h>
-
 size_t
 xstrncpy(char *dest, const char *src, size_t n) {
     size_t i;
@@ -49,7 +47,7 @@ truncated:
 char *
 strquote(const char *src) {
     size_t len = strlen(src);
-    char *quoted = SDL_malloc(len + 3);
+    char *quoted = malloc(len + 3);
     if (!quoted) {
         return NULL;
     }
@@ -167,7 +165,7 @@ utf8_to_wide_char(const char *utf8) {
         return NULL;
     }
 
-    wchar_t *wide = SDL_malloc(len * sizeof(wchar_t));
+    wchar_t *wide = malloc(len * sizeof(wchar_t));
     if (!wide) {
         return NULL;
     }
@@ -183,7 +181,7 @@ utf8_from_wide_char(const wchar_t *ws) {
         return NULL;
     }
 
-    char *utf8 = SDL_malloc(len);
+    char *utf8 = malloc(len);
     if (!utf8) {
         return NULL;
     }

app/src/util/thread.c

@@ -0,0 +1,159 @@
+#include "thread.h"
+
+#include <assert.h>
+#include <SDL2/SDL_thread.h>
+
+#include "log.h"
+
+bool
+sc_thread_create(sc_thread *thread, sc_thread_fn fn, const char *name,
+                 void *userdata) {
+    SDL_Thread *sdl_thread = SDL_CreateThread(fn, name, userdata);
+    if (!sdl_thread) {
+        return false;
+    }
+
+    thread->thread = sdl_thread;
+    return true;
+}
+
+void
+sc_thread_join(sc_thread *thread, int *status) {
+    SDL_WaitThread(thread->thread, status);
+}
+
+bool
+sc_mutex_init(sc_mutex *mutex) {
+    SDL_mutex *sdl_mutex = SDL_CreateMutex();
+    if (!sdl_mutex) {
+        return false;
+    }
+
+    mutex->mutex = sdl_mutex;
+#ifndef NDEBUG
+    mutex->locker = 0;
+#endif
+    return true;
+}
+
+void
+sc_mutex_destroy(sc_mutex *mutex) {
+    SDL_DestroyMutex(mutex->mutex);
+}
+
+void
+sc_mutex_lock(sc_mutex *mutex) {
+    // SDL mutexes are recursive, but we don't want to use recursive mutexes
+    assert(!sc_mutex_held(mutex));
+    int r = SDL_LockMutex(mutex->mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not lock mutex: %s", SDL_GetError());
+        abort();
+    }
+
+    mutex->locker = sc_thread_get_id();
+#else
+    (void) r;
+#endif
+}
+
+void
+sc_mutex_unlock(sc_mutex *mutex) {
+#ifndef NDEBUG
+    mutex->locker = 0;
+#endif
+    int r = SDL_UnlockMutex(mutex->mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not lock mutex: %s", SDL_GetError());
+        abort();
+    }
+#else
+    (void) r;
+#endif
+}
+
+sc_thread_id
+sc_thread_get_id(void) {
+    return SDL_ThreadID();
+}
+
+#ifndef NDEBUG
+bool
+sc_mutex_held(struct sc_mutex *mutex) {
+    return mutex->locker == sc_thread_get_id();
+}
+#endif
+
+bool
+sc_cond_init(sc_cond *cond) {
+    SDL_cond *sdl_cond = SDL_CreateCond();
+    if (!sdl_cond) {
+        return false;
+    }
+
+    cond->cond = sdl_cond;
+    return true;
+}
+
+void
+sc_cond_destroy(sc_cond *cond) {
+    SDL_DestroyCond(cond->cond);
+}
+
+void
+sc_cond_wait(sc_cond *cond, sc_mutex *mutex) {
+    int r = SDL_CondWait(cond->cond, mutex->mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not wait on condition: %s", SDL_GetError());
+        abort();
+    }
+
+    mutex->locker = sc_thread_get_id();
+#else
+    (void) r;
+#endif
+}
+
+bool
+sc_cond_timedwait(sc_cond *cond, sc_mutex *mutex, uint32_t ms) {
+    int r = SDL_CondWaitTimeout(cond->cond, mutex->mutex, ms);
+#ifndef NDEBUG
+    if (r < 0) {
+        LOGC("Could not wait on condition with timeout: %s", SDL_GetError());
+        abort();
+    }
+
+    mutex->locker = sc_thread_get_id();
+#endif
+    assert(r == 0 || r == SDL_MUTEX_TIMEDOUT);
+    return r == 0;
+}
+
+void
+sc_cond_signal(sc_cond *cond) {
+    int r = SDL_CondSignal(cond->cond);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not signal a condition: %s", SDL_GetError());
+        abort();
+    }
+#else
+    (void) r;
+#endif
+}
+
+void
+sc_cond_broadcast(sc_cond *cond) {
+    int r = SDL_CondBroadcast(cond->cond);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not broadcast a condition: %s", SDL_GetError());
+        abort();
+    }
+#else
+    (void) r;
+#endif
+}

app/src/util/thread.h

@@ -0,0 +1,81 @@
+#ifndef SC_THREAD_H
+#define SC_THREAD_H
+
+#include "common.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/* Forward declarations */
+typedef struct SDL_Thread SDL_Thread;
+typedef struct SDL_mutex SDL_mutex;
+typedef struct SDL_cond SDL_cond;
+
+typedef int sc_thread_fn(void *);
+typedef unsigned int sc_thread_id;
+
+typedef struct sc_thread {
+    SDL_Thread *thread;
+} sc_thread;
+
+typedef struct sc_mutex {
+    SDL_mutex *mutex;
+#ifndef NDEBUG
+    sc_thread_id locker;
+#endif
+} sc_mutex;
+
+typedef struct sc_cond {
+    SDL_cond *cond;
+} sc_cond;
+
+bool
+sc_thread_create(sc_thread *thread, sc_thread_fn fn, const char *name,
+                 void *userdata);
+
+void
+sc_thread_join(sc_thread *thread, int *status);
+
+bool
+sc_mutex_init(sc_mutex *mutex);
+
+void
+sc_mutex_destroy(sc_mutex *mutex);
+
+void
+sc_mutex_lock(sc_mutex *mutex);
+
+void
+sc_mutex_unlock(sc_mutex *mutex);
+
+sc_thread_id
+sc_thread_get_id(void);
+
+#ifndef NDEBUG
+bool
+sc_mutex_held(struct sc_mutex *mutex);
+# define sc_mutex_assert(mutex) assert(sc_mutex_held(mutex))
+#else
+# define sc_mutex_assert(mutex)
+#endif
+
+bool
+sc_cond_init(sc_cond *cond);
+
+void
+sc_cond_destroy(sc_cond *cond);
+
+void
+sc_cond_wait(sc_cond *cond, sc_mutex *mutex);
+
+// return true on signaled, false on timeout
+bool
+sc_cond_timedwait(sc_cond *cond, sc_mutex *mutex, uint32_t ms);
+
+void
+sc_cond_signal(sc_cond *cond);
+
+void
+sc_cond_broadcast(sc_cond *cond);
+
+#endif

app/src/video_buffer.c

@@ -1,11 +1,9 @@
 #include "video_buffer.h"
 
 #include <assert.h>
-#include <SDL2/SDL_mutex.h>
 #include <libavutil/avutil.h>
 #include <libavformat/avformat.h>
 
-#include "util/lock.h"
 #include "util/log.h"
 
 bool
@@ -13,22 +11,31 @@ video_buffer_init(struct video_buffer *vb, struct fps_counter *fps_counter,
                   bool render_expired_frames) {
     vb->fps_counter = fps_counter;
 
-    if (!(vb->decoding_frame = av_frame_alloc())) {
+    vb->decoding_frame = av_frame_alloc();
+    if (!vb->decoding_frame) {
         goto error_0;
     }
 
-    if (!(vb->rendering_frame = av_frame_alloc())) {
+    vb->pending_frame = av_frame_alloc();
+    if (!vb->pending_frame) {
         goto error_1;
     }
 
-    if (!(vb->mutex = SDL_CreateMutex())) {
+    vb->rendering_frame = av_frame_alloc();
+    if (!vb->rendering_frame) {
         goto error_2;
     }
 
+    bool ok = sc_mutex_init(&vb->mutex);
+    if (!ok) {
+        goto error_3;
+    }
+
     vb->render_expired_frames = render_expired_frames;
     if (render_expired_frames) {
-        if (!(vb->rendering_frame_consumed_cond = SDL_CreateCond())) {
+        ok = sc_cond_init(&vb->pending_frame_consumed_cond);
-            SDL_DestroyMutex(vb->mutex);
+        if (!ok) {
+            sc_mutex_destroy(&vb->mutex);
             goto error_2;
         }
         // interrupted is not used if expired frames are not rendered
@@ -38,12 +45,14 @@ video_buffer_init(struct video_buffer *vb, struct fps_counter *fps_counter,
 
     // there is initially no rendering frame, so consider it has already been
     // consumed
-    vb->rendering_frame_consumed = true;
+    vb->pending_frame_consumed = true;
 
     return true;
 
-error_2:
+error_3:
     av_frame_free(&vb->rendering_frame);
+error_2:
+    av_frame_free(&vb->pending_frame);
 error_1:
     av_frame_free(&vb->decoding_frame);
 error_0:
@@ -53,60 +62,78 @@ error_0:
 void
 video_buffer_destroy(struct video_buffer *vb) {
     if (vb->render_expired_frames) {
-        SDL_DestroyCond(vb->rendering_frame_consumed_cond);
+        sc_cond_destroy(&vb->pending_frame_consumed_cond);
     }
-    SDL_DestroyMutex(vb->mutex);
+    sc_mutex_destroy(&vb->mutex);
     av_frame_free(&vb->rendering_frame);
+    av_frame_free(&vb->pending_frame);
     av_frame_free(&vb->decoding_frame);
 }
 
 static void
-video_buffer_swap_frames(struct video_buffer *vb) {
+video_buffer_swap_decoding_frame(struct video_buffer *vb) {
+    sc_mutex_assert(&vb->mutex);
     AVFrame *tmp = vb->decoding_frame;
-    vb->decoding_frame = vb->rendering_frame;
+    vb->decoding_frame = vb->pending_frame;
-    vb->rendering_frame = tmp;
+    vb->pending_frame = tmp;
+}
+
+static void
+video_buffer_swap_rendering_frame(struct video_buffer *vb) {
+    sc_mutex_assert(&vb->mutex);
+    AVFrame *tmp = vb->rendering_frame;
+    vb->rendering_frame = vb->pending_frame;
+    vb->pending_frame = tmp;
 }
 
 void
 video_buffer_offer_decoded_frame(struct video_buffer *vb,
                                  bool *previous_frame_skipped) {
-    mutex_lock(vb->mutex);
+    sc_mutex_lock(&vb->mutex);
     if (vb->render_expired_frames) {
         // wait for the current (expired) frame to be consumed
-        while (!vb->rendering_frame_consumed && !vb->interrupted) {
+        while (!vb->pending_frame_consumed && !vb->interrupted) {
-            cond_wait(vb->rendering_frame_consumed_cond, vb->mutex);
+            sc_cond_wait(&vb->pending_frame_consumed_cond, &vb->mutex);
         }
-    } else if (!vb->rendering_frame_consumed) {
+    } else if (!vb->pending_frame_consumed) {
         fps_counter_add_skipped_frame(vb->fps_counter);
     }
 
-    video_buffer_swap_frames(vb);
+    video_buffer_swap_decoding_frame(vb);
 
-    *previous_frame_skipped = !vb->rendering_frame_consumed;
+    *previous_frame_skipped = !vb->pending_frame_consumed;
-    vb->rendering_frame_consumed = false;
+    vb->pending_frame_consumed = false;
 
-    mutex_unlock(vb->mutex);
+    sc_mutex_unlock(&vb->mutex);
 }
 
 const AVFrame *
-video_buffer_consume_rendered_frame(struct video_buffer *vb) {
+video_buffer_take_rendering_frame(struct video_buffer *vb) {
-    assert(!vb->rendering_frame_consumed);
+    sc_mutex_lock(&vb->mutex);
-    vb->rendering_frame_consumed = true;
+    assert(!vb->pending_frame_consumed);
+    vb->pending_frame_consumed = true;
+
     fps_counter_add_rendered_frame(vb->fps_counter);
+
+    video_buffer_swap_rendering_frame(vb);
+
     if (vb->render_expired_frames) {
         // unblock video_buffer_offer_decoded_frame()
-        cond_signal(vb->rendering_frame_consumed_cond);
+        sc_cond_signal(&vb->pending_frame_consumed_cond);
     }
+    sc_mutex_unlock(&vb->mutex);
+
+    // rendering_frame is only written from this thread, no need to lock
     return vb->rendering_frame;
 }
 
 void
 video_buffer_interrupt(struct video_buffer *vb) {
     if (vb->render_expired_frames) {
-        mutex_lock(vb->mutex);
+        sc_mutex_lock(&vb->mutex);
         vb->interrupted = true;
-        mutex_unlock(vb->mutex);
+        sc_mutex_unlock(&vb->mutex);
         // wake up blocking wait
-        cond_signal(vb->rendering_frame_consumed_cond);
+        sc_cond_signal(&vb->pending_frame_consumed_cond);
     }
 }

app/src/video_buffer.h

@@ -4,21 +4,42 @@
 #include "common.h"
 
 #include <stdbool.h>
-#include <SDL2/SDL_mutex.h>
 
 #include "fps_counter.h"
+#include "util/thread.h"
 
 // forward declarations
 typedef struct AVFrame AVFrame;
 
+/**
+ * There are 3 frames in memory:
+ *  - one frame is held by the decoder (decoding_frame)
+ *  - one frame is held by the renderer (rendering_frame)
+ *  - one frame is shared between the decoder and the renderer (pending_frame)
+ *
+ * The decoder decodes a packet into the decoding_frame (it may takes time).
+ *
+ * Once the frame is decoded, it calls video_buffer_offer_decoded_frame(),
+ * which swaps the decoding and pending frames.
+ *
+ * When the renderer is notified that a new frame is available, it calls
+ * video_buffer_take_rendering_frame() to retrieve it, which swaps the pending
+ * and rendering frames. The frame is valid until the next call, without
+ * blocking the decoder.
+ */
+
 struct video_buffer {
     AVFrame *decoding_frame;
+    AVFrame *pending_frame;
     AVFrame *rendering_frame;
-    SDL_mutex *mutex;
+
+    sc_mutex mutex;
     bool render_expired_frames;
     bool interrupted;
-    SDL_cond *rendering_frame_consumed_cond;
+
-    bool rendering_frame_consumed;
+    sc_cond pending_frame_consumed_cond;
+    bool pending_frame_consumed;
+
     struct fps_counter *fps_counter;
 };
 
@@ -30,18 +51,15 @@ void
 video_buffer_destroy(struct video_buffer *vb);
 
 // set the decoded frame as ready for rendering
-// this function locks frames->mutex during its execution
 // the output flag is set to report whether the previous frame has been skipped
 void
 video_buffer_offer_decoded_frame(struct video_buffer *vb,
                                  bool *previous_frame_skipped);
 
 // mark the rendering frame as consumed and return it
-// MUST be called with frames->mutex locked!!!
+// the frame is valid until the next call to this function
-// the caller is expected to render the returned frame to some texture before
-// unlocking frames->mutex
 const AVFrame *
-video_buffer_consume_rendered_frame(struct video_buffer *vb);
+video_buffer_take_rendering_frame(struct video_buffer *vb);
 
 // wake up and avoid any blocking call
 void

app/tests/test_strutil.c

@@ -4,7 +4,6 @@
 #include <limits.h>
 #include <stdio.h>
 #include <string.h>
-#include <SDL2/SDL.h>
 
 #include "util/str_util.h"
 
@@ -138,7 +137,7 @@ static void test_strquote(void) {
     // add '"' at the beginning and the end
     assert(!strcmp("\"abcde\"", out));
 
-    SDL_free(out);
+    free(out);
 }
 
 static void test_utf8_truncate(void) {