Update documentation for --no-window

PR #4868 <https://github.com/Genymobile/scrcpy/pull/4868>

app/src/audio_player.c

@@ -66,6 +66,8 @@ static void SDLCALL
 sc_audio_player_sdl_callback(void *userdata, uint8_t *stream, int len_int) {
     struct sc_audio_player *ap = userdata;
 
+    // This callback is called with the lock used by SDL_LockAudioDevice()
+
     assert(len_int > 0);
     size_t len = len_int;
     uint32_t count = TO_SAMPLES(len);
@@ -179,19 +181,29 @@ sc_audio_player_frame_sink_push(struct sc_frame_sink *sink,
     if (written < samples) {
         uint32_t remaining = samples - written;
 
-        assert(remaining <= cap);
-        skipped_samples = sc_audiobuf_truncate(&ap->buf, cap - remaining);
+        // All samples that could be written without locking have been written,
+        // now we need to lock to drop/consume old samples
+        SDL_LockAudioDevice(ap->device);
 
-        LOGW("Audio buffer full, %" PRIu32 " samples dropped", skipped_samples);
+        // Retry with the lock
+        written += sc_audiobuf_write(&ap->buf,
+                                     swr_buf + TO_BYTES(written),
+                                     remaining);
+        if (written < samples) {
+            remaining = samples - written;
+            // Still insufficient, drop old samples to make space
+            skipped_samples = sc_audiobuf_read(&ap->buf, NULL, remaining);
+            assert(skipped_samples == remaining);
 
-        // Now there is enough space
-        uint32_t w = sc_audiobuf_write(&ap->buf,
-                                       swr_buf + TO_BYTES(written),
-                                       remaining);
-        assert(w == remaining);
-        (void) w;
+            // Now there is enough space
+            uint32_t w = sc_audiobuf_write(&ap->buf,
+                                           swr_buf + TO_BYTES(written),
+                                           remaining);
+            assert(w == remaining);
+            (void) w;
+        }
 
-        written = samples;
+        SDL_UnlockAudioDevice(ap->device);
     }
 
     uint32_t underflow = 0;
@@ -213,22 +225,30 @@ sc_audio_player_frame_sink_push(struct sc_frame_sink *sink,
 
     uint32_t can_read = sc_audiobuf_can_read(&ap->buf);
     if (can_read > max_buffered_samples) {
-        uint32_t skipped = sc_audiobuf_truncate(&ap->buf, max_buffered_samples);
-        assert(skipped);
-
-        if (played) {
-            LOGD("[Audio] Buffering threshold exceeded, skipping %" PRIu32
-                 " samples", skipped);
-#ifndef SC_AUDIO_PLAYER_NDEBUG
-        } else {
-            LOGD("[Audio] Playback not started, skipping %" PRIu32 " samples",
-                 skipped);
-#endif
-        }
-
-        skipped_samples += skipped;
+        uint32_t skip_samples = 0;
 
+        SDL_LockAudioDevice(ap->device);
         can_read = sc_audiobuf_can_read(&ap->buf);
+        if (can_read > max_buffered_samples) {
+            skip_samples = can_read - max_buffered_samples;
+            uint32_t r = sc_audiobuf_read(&ap->buf, NULL, skip_samples);
+            assert(r == skip_samples);
+            (void) r;
+            skipped_samples += skip_samples;
+        }
+        SDL_UnlockAudioDevice(ap->device);
+
+        if (skip_samples) {
+            if (played) {
+                LOGD("[Audio] Buffering threshold exceeded, skipping %" PRIu32
+                     " samples", skip_samples);
+#ifndef SC_AUDIO_PLAYER_NDEBUG
+            } else {
+                LOGD("[Audio] Playback not started, skipping %" PRIu32
+                     " samples", skip_samples);
+#endif
+            }
+        }
     }
 
     atomic_store_explicit(&ap->received, true, memory_order_relaxed);
@@ -388,7 +408,7 @@ sc_audio_player_frame_sink_open(struct sc_frame_sink *sink,
     // Use a ring-buffer of the target buffering size plus 1 second between the
     // producer and the consumer. It's too big on purpose, to guarantee that
     // the producer and the consumer will be able to access it in parallel
-    // without dropping samples.
+    // without locking.
     uint32_t audiobuf_samples = ap->target_buffering + ap->sample_rate;
 
     size_t sample_size = ap->nb_channels * ap->out_bytes_per_sample;

app/src/cli.c

@@ -2585,11 +2585,6 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
 
 #ifdef HAVE_V4L2
     if (v4l2) {
-        if (!opts->video) {
-            LOGE("V4L2 sink requires video capture, but --no-video was set.");
-            return false;
-        }
-
         if (opts->lock_video_orientation ==
                 SC_LOCK_VIDEO_ORIENTATION_UNLOCKED) {
             LOGI("Video orientation is locked for v4l2 sink. "
@@ -2618,8 +2613,9 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             if (otg) {
                 opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_AOA;
             } else if (!opts->video_playback) {
-                LOGI("No video mirroring, mouse mode switched to UHID");
-                opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_UHID;
+                LOGI("No video mirroring, SDK mouse disabled (you might want "
+                     "--mouse=uhid)");
+                opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_DISABLED;
             } else {
                 opts->mouse_input_mode = SC_MOUSE_INPUT_MODE_SDK;
             }
@@ -2738,11 +2734,6 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     }
 
     if (opts->record_filename) {
-        if (!opts->video && !opts->audio) {
-            LOGE("Video and audio disabled, nothing to record");
-            return false;
-        }
-
         if (!opts->record_format) {
             opts->record_format = guess_record_format(opts->record_filename);
             if (!opts->record_format) {

app/src/controller.c

@@ -6,19 +6,8 @@
 
 #define SC_CONTROL_MSG_QUEUE_MAX 64
 
-static void
-sc_controller_receiver_on_error(struct sc_receiver *receiver, void *userdata) {
-    (void) receiver;
-
-    struct sc_controller *controller = userdata;
-    // Forward the event to the controller listener
-    controller->cbs->on_error(controller, controller->cbs_userdata);
-}
-
 bool
-sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
-                   const struct sc_controller_callbacks *cbs,
-                   void *cbs_userdata) {
+sc_controller_init(struct sc_controller *controller, sc_socket control_socket) {
     sc_vecdeque_init(&controller->queue);
 
     bool ok = sc_vecdeque_reserve(&controller->queue, SC_CONTROL_MSG_QUEUE_MAX);
@@ -26,12 +15,7 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
         return false;
     }
 
-    static const struct sc_receiver_callbacks receiver_cbs = {
-        .on_error = sc_controller_receiver_on_error,
-    };
-
-    ok = sc_receiver_init(&controller->receiver, control_socket, &receiver_cbs,
-                          controller);
+    ok = sc_receiver_init(&controller->receiver, control_socket);
     if (!ok) {
         sc_vecdeque_destroy(&controller->queue);
         return false;
@@ -55,10 +39,6 @@ sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
     controller->control_socket = control_socket;
     controller->stopped = false;
 
-    assert(cbs && cbs->on_error);
-    controller->cbs = cbs;
-    controller->cbs_userdata = cbs_userdata;
-
     return true;
 }
 
@@ -145,16 +125,10 @@ run_controller(void *data) {
         sc_control_msg_destroy(&msg);
         if (!ok) {
             LOGD("Could not write msg to socket");
-            goto error;
+            break;
         }
     }
-
     return 0;
-
-error:
-    controller->cbs->on_error(controller, controller->cbs_userdata);
-
-    return 1; // ignored
 }
 
 bool

app/src/controller.h

@@ -22,19 +22,10 @@ struct sc_controller {
     bool stopped;
     struct sc_control_msg_queue queue;
     struct sc_receiver receiver;
-
-    const struct sc_controller_callbacks *cbs;
-    void *cbs_userdata;
-};
-
-struct sc_controller_callbacks {
-    void (*on_error)(struct sc_controller *controller, void *userdata);
 };
 
 bool
-sc_controller_init(struct sc_controller *controller, sc_socket control_socket,
-                   const struct sc_controller_callbacks *cbs,
-                   void *cbs_userdata);
+sc_controller_init(struct sc_controller *controller, sc_socket control_socket);
 
 void
 sc_controller_configure(struct sc_controller *controller,

app/src/events.h

@@ -7,4 +7,3 @@
 #define SC_EVENT_RECORDER_ERROR           (SDL_USEREVENT + 6)
 #define SC_EVENT_SCREEN_INIT_SIZE         (SDL_USEREVENT + 7)
 #define SC_EVENT_TIME_LIMIT_REACHED       (SDL_USEREVENT + 8)
-#define SC_EVENT_CONTROLLER_ERROR         (SDL_USEREVENT + 9)

app/src/input_manager.c

@@ -748,8 +748,7 @@ sc_input_manager_process_mouse_button(struct sc_input_manager *im,
         }
 
         // double-click on black borders resize to fit the device screen
-        bool video = im->screen->video;
-        if (video && event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
+        if (event->button == SDL_BUTTON_LEFT && event->clicks == 2) {
             int32_t x = event->x;
             int32_t y = event->y;
             sc_screen_hidpi_scale_coords(im->screen, &x, &y);

app/src/receiver.c

@@ -10,8 +10,7 @@
 #include "util/str.h"
 
 bool
-sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
-                 const struct sc_receiver_callbacks *cbs, void *cbs_userdata) {
+sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket) {
     bool ok = sc_mutex_init(&receiver->mutex);
     if (!ok) {
         return false;
@@ -21,10 +20,6 @@ sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
     receiver->acksync = NULL;
     receiver->uhid_devices = NULL;
 
-    assert(cbs && cbs->on_error);
-    receiver->cbs = cbs;
-    receiver->cbs_userdata = cbs_userdata;
-
     return true;
 }
 
@@ -157,8 +152,6 @@ run_receiver(void *data) {
         }
     }
 
-    receiver->cbs->on_error(receiver, receiver->cbs_userdata);
-
     return 0;
 }
 

app/src/receiver.h

@@ -19,18 +19,10 @@ struct sc_receiver {
 
     struct sc_acksync *acksync;
     struct sc_uhid_devices *uhid_devices;
-
-    const struct sc_receiver_callbacks *cbs;
-    void *cbs_userdata;
-};
-
-struct sc_receiver_callbacks {
-    void (*on_error)(struct sc_receiver *receiver, void *userdata);
 };
 
 bool
-sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket,
-                 const struct sc_receiver_callbacks *cbs, void *cbs_userdata);
+sc_receiver_init(struct sc_receiver *receiver, sc_socket control_socket);
 
 void
 sc_receiver_destroy(struct sc_receiver *receiver);

app/src/scrcpy.c

@@ -174,9 +174,6 @@ event_loop(struct scrcpy *s) {
             case SC_EVENT_DEMUXER_ERROR:
                 LOGE("Demuxer error");
                 return SCRCPY_EXIT_FAILURE;
-            case SC_EVENT_CONTROLLER_ERROR:
-                LOGE("Controller error");
-                return SCRCPY_EXIT_FAILURE;
             case SC_EVENT_RECORDER_ERROR:
                 LOGE("Recorder error");
                 return SCRCPY_EXIT_FAILURE;
@@ -268,16 +265,6 @@ sc_audio_demuxer_on_ended(struct sc_demuxer *demuxer,
     }
 }
 
-static void
-sc_controller_on_error(struct sc_controller *controller, void *userdata) {
-    // Note: this function may be called twice, once from the controller thread
-    // and once from the receiver thread
-    (void) controller;
-    (void) userdata;
-
-    PUSH_EVENT(SC_EVENT_CONTROLLER_ERROR);
-}
-
 static void
 sc_server_on_connection_failed(struct sc_server *server, void *userdata) {
     (void) server;
@@ -566,12 +553,7 @@ scrcpy(struct scrcpy_options *options) {
     struct sc_mouse_processor *mp = NULL;
 
     if (options->control) {
-        static const struct sc_controller_callbacks controller_cbs = {
-            .on_error = sc_controller_on_error,
-        };
-
-        if (!sc_controller_init(&s->controller, s->server.control_socket,
-            &controller_cbs, NULL)) {
+        if (!sc_controller_init(&s->controller, s->server.control_socket)) {
             goto end;
         }
         controller_initialized = true;

app/src/util/audiobuf.c

@@ -37,35 +37,34 @@ sc_audiobuf_read(struct sc_audiobuf *buf, void *to_, uint32_t samples_count) {
     assert(samples_count);
 
     uint8_t *to = to_;
-    assert(to);
 
-    // The tail cursor may be updated by the writer thread to drop samples
-    uint32_t tail = atomic_load_explicit(&buf->tail, memory_order_acquire);
+    // Only the reader thread can write tail without synchronization, so
+    // memory_order_relaxed is sufficient
+    uint32_t tail = atomic_load_explicit(&buf->tail, memory_order_relaxed);
 
     // The head cursor is updated after the data is written to the array
     uint32_t head = atomic_load_explicit(&buf->head, memory_order_acquire);
 
     uint32_t can_read = (buf->alloc_size + head - tail) % buf->alloc_size;
-    if (!can_read) {
-        return 0;
-    }
     if (samples_count > can_read) {
         samples_count = can_read;
     }
 
-    uint32_t right_count = buf->alloc_size - tail;
-    if (right_count > samples_count) {
-        right_count = samples_count;
-    }
-    memcpy(to,
-           buf->data + (tail * buf->sample_size),
-           right_count * buf->sample_size);
+    if (to) {
+        uint32_t right_count = buf->alloc_size - tail;
+        if (right_count > samples_count) {
+            right_count = samples_count;
+        }
+        memcpy(to,
+               buf->data + (tail * buf->sample_size),
+               right_count * buf->sample_size);
 
-    if (samples_count > right_count) {
-        uint32_t left_count = samples_count - right_count;
-        memcpy(to + (right_count * buf->sample_size),
-               buf->data,
-               left_count * buf->sample_size);
+        if (samples_count > right_count) {
+            uint32_t left_count = samples_count - right_count;
+            memcpy(to + (right_count * buf->sample_size),
+                   buf->data,
+                   left_count * buf->sample_size);
+        }
     }
 
     uint32_t new_tail = (tail + samples_count) % buf->alloc_size;
@@ -87,9 +86,6 @@ sc_audiobuf_write(struct sc_audiobuf *buf, const void *from_,
     uint32_t tail = atomic_load_explicit(&buf->tail, memory_order_acquire);
 
     uint32_t can_write = (buf->alloc_size + tail - head - 1) % buf->alloc_size;
-    if (!can_write) {
-        return 0;
-    }
     if (samples_count > can_write) {
         samples_count = can_write;
     }
@@ -114,29 +110,3 @@ sc_audiobuf_write(struct sc_audiobuf *buf, const void *from_,
 
     return samples_count;
 }
-
-uint32_t
-sc_audiobuf_truncate(struct sc_audiobuf *buf, uint32_t samples_limit) {
-    for (;;) {
-        // Only the writer thread can write head, so memory_order_relaxed is
-        // sufficient
-        uint32_t head = atomic_load_explicit(&buf->head, memory_order_relaxed);
-
-        // The tail cursor is updated after the data is consumed by the reader
-        uint32_t tail = atomic_load_explicit(&buf->tail, memory_order_acquire);
-
-        uint32_t can_read = (buf->alloc_size + head - tail) % buf->alloc_size;
-        if (can_read <= samples_limit) {
-            // Nothing to truncate
-            return 0;
-        }
-
-        uint32_t skip = can_read - samples_limit;
-        uint32_t new_tail = (tail + skip) % buf->alloc_size;
-        if (atomic_compare_exchange_weak_explicit(&buf->tail, &tail, new_tail,
-                                                  memory_order_acq_rel,
-                                                  memory_order_acquire)) {
-            return skip;
-        }
-    }
-}

app/src/util/audiobuf.h

@@ -49,16 +49,6 @@ uint32_t
 sc_audiobuf_write(struct sc_audiobuf *buf, const void *from,
                   uint32_t samples_count);
 
-/**
- * Drop old samples to keep at most sample_limit samples
- *
- * Must be called by the writer thread.
- *
- * \return the number of samples dropped
- */
-uint32_t
-sc_audiobuf_truncate(struct sc_audiobuf *buf, uint32_t samples_limit);
-
 static inline uint32_t
 sc_audiobuf_capacity(struct sc_audiobuf *buf) {
     assert(buf->alloc_size);

doc/control.md

@@ -17,26 +17,11 @@ Read [keyboard](keyboard.md) and [mouse](mouse.md).
 
 ## Control only
 
-To control the device without mirroring:
+To control only with UHID mouse and keyboard:
 
 ```bash
-scrcpy --no-video --no-audio
-```
-
-By default, mouse mode is switched to UHID if video mirroring is disabled (a
-relative mouse mode is required).
-
-To also use a UHID keyboard, set it explicitly:
-
-```bash
-scrcpy --no-video --no-audio --keyboard=uhid
-scrcpy --no-video --no-audio -K  # short version
-```
-
-To use AOA instead (over USB only):
-
-```bash
-scrcpy --no-video --no-audio --keyboard=aoa --mouse=aoa
+scrcpy --no-video --no-audio --keyboard=uhid --mouse=uhid
+scrcpy --no-video --no-audio -KM  # short version
 ```
 
 

doc/otg.md

@@ -39,13 +39,13 @@ It only works if the device is connected over USB.
 See [FAQ](/FAQ.md#otg-issues-on-windows).
 
 
-## Control only
+## Control-only
 
 Note that the purpose of OTG is to control the device without USB debugging
 (adb).
 
-If you want to solely control the device without mirroring while USB debugging
-is enabled, then OTG mode is not necessary.
+If you want to only control the device without mirroring while USB debugging is
+enabled, then OTG mode is not necessary.
 
 Instead, disable video and audio, and select UHID (or AOA):
 

server/src/main/java/com/genymobile/scrcpy/SurfaceEncoder.java

@@ -48,7 +48,7 @@ public class SurfaceEncoder implements AsyncProcessor {
         this.downsizeOnError = downsizeOnError;
     }
 
-    private void streamCapture() throws IOException, ConfigurationException {
+    private void streamScreen() throws IOException, ConfigurationException {
         Codec codec = streamer.getCodec();
         MediaCodec mediaCodec = createMediaCodec(codec, encoderName);
         MediaFormat format = createFormat(codec.getMimeType(), videoBitRate, maxFps, codecOptions);
@@ -254,7 +254,7 @@ public class SurfaceEncoder implements AsyncProcessor {
             Looper.prepare();
 
             try {
-                streamCapture();
+                streamScreen();
             } catch (ConfigurationException e) {
                 // Do not print stack trace, a user-friendly error-message has already been logged
             } catch (IOException e) {