Retrieve icon decoder directly

The call to av_find_best_stream() gives the decoder directly, there is
no need to retrieve it afterwards in a separate step.

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 +181,31 @@ 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;
+        SDL_UnlockAudioDevice(ap->device);
 
-        written = samples;
+        if (written < samples) {
+            // Now there is enough space
+            uint32_t w = sc_audiobuf_write(&ap->buf,
+                                           swr_buf + TO_BYTES(written),
+                                           remaining);
+            assert(w == remaining);
+            (void) w;
+        }
     }
 
     uint32_t underflow = 0;
@@ -213,22 +227,30 @@ 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 +410,7 @@ 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/icon.c

@@ -78,7 +78,10 @@ decode_image(const char *path) {
         goto close_input;
     }
 
-    int stream = av_find_best_stream(ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
+    const AVCodec *codec;
+
+    int stream =
+        av_find_best_stream(ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &codec, 0);
     if (stream < 0 ) {
         LOGE("Could not find best image stream");
         goto close_input;
@@ -86,12 +89,6 @@ decode_image(const char *path) {
 
     AVCodecParameters *params = ctx->streams[stream]->codecpar;
 
-    const AVCodec *codec = avcodec_find_decoder(params->codec_id);
-    if (!codec) {
-        LOGE("Could not find image decoder");
-        goto close_input;
-    }
-
     AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
     if (!codec_ctx) {
         LOG_OOM();

app/src/sys/win/process.c

@@ -176,6 +176,8 @@ sc_process_execute_p(const char *const argv[], HANDLE *handle, unsigned flags,
         free(lpAttributeList);
     }
 
+    CloseHandle(pi.hThread);
+
     // These handles are used by the child process, close them for this process
     if (pin) {
         CloseHandle(stdin_read_handle);

app/src/util/audiobuf.c

@@ -37,10 +37,10 @@ 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);
@@ -53,19 +53,21 @@ sc_audiobuf_read(struct sc_audiobuf *buf, void *to_, uint32_t samples_count) {
         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;
@@ -114,29 +116,3 @@ 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);