Use a callback to notify a new decoded frame

Make the decoder independant of the SDL event mechanism.

app/src/decoder.c

@@ -2,7 +2,6 @@
 
 #include <libavformat/avformat.h>
 #include <libavutil/time.h>
-#include <SDL2/SDL_events.h>
 #include <unistd.h>
 
 #include "events.h"
@@ -18,18 +17,22 @@ push_frame(struct decoder *decoder) {
     video_buffer_offer_decoded_frame(decoder->video_buffer,
                                      &previous_frame_skipped);
     if (previous_frame_skipped) {
-        // the previous EVENT_NEW_FRAME will consume this frame
+        // the previous callback will consume this frame
         return;
     }
-    static SDL_Event new_frame_event = {
-        .type = EVENT_NEW_FRAME,
-    };
-    SDL_PushEvent(&new_frame_event);
+
+    decoder->cbs->on_new_frame(decoder, decoder->cbs_userdata);
 }
 
 void
-decoder_init(struct decoder *decoder, struct video_buffer *vb) {
+decoder_init(struct decoder *decoder, struct video_buffer *vb,
+             const struct decoder_callbacks *cbs, void *cbs_userdata) {
     decoder->video_buffer = vb;
+
+    assert(cbs);
+    assert(cbs->on_new_frame);
+    decoder->cbs = cbs;
+    decoder->cbs_userdata = cbs_userdata;
 }
 
 bool

app/src/decoder.h

@@ -11,10 +11,20 @@ struct video_buffer;
 struct decoder {
     struct video_buffer *video_buffer;
     AVCodecContext *codec_ctx;
+
+    const struct decoder_callbacks *cbs;
+    void *cbs_userdata;
+};
+
+struct decoder_callbacks {
+     // Called when a new frame can be consumed by
+     // video_buffer_take_rendering_frame(decoder->video_buffer).
+    void (*on_new_frame)(struct decoder *decoder, void *userdata);
 };
 
 void
-decoder_init(struct decoder *decoder, struct video_buffer *vb);
+decoder_init(struct decoder *decoder, struct video_buffer *vb,
+             const struct decoder_callbacks *cbs, void *cbs_userdata);
 
 bool
 decoder_open(struct decoder *decoder, const AVCodec *codec);

app/src/scrcpy.c

@@ -306,6 +306,17 @@ av_log_callback(void *avcl, int level, const char *fmt, va_list vl) {
     free(local_fmt);
 }
 
+static void
+decoder_on_new_frame(struct decoder *decoder, void *userdata) {
+    (void) decoder;
+    (void) userdata;
+
+    static SDL_Event new_frame_event = {
+        .type = EVENT_NEW_FRAME,
+    };
+    SDL_PushEvent(&new_frame_event);
+}
+
 bool
 scrcpy(const struct scrcpy_options *options) {
     if (!server_init(&server)) {
@@ -386,7 +397,11 @@ scrcpy(const struct scrcpy_options *options) {
             file_handler_initialized = true;
         }
 
-        decoder_init(&decoder, &video_buffer);
+        static const struct decoder_callbacks decoder_cbs = {
+            .on_new_frame = decoder_on_new_frame,
+        };
+
+        decoder_init(&decoder, &video_buffer, &decoder_cbs, NULL);
         dec = &decoder;
     }