Provide decoder_init()

Expose an initializer so that the caller does not have to guess what
fields must be initialized.

app/src/decoder.c

@@ -140,6 +140,11 @@ run_finally_free_codec_ctx:
     return ret;
 }
 
+void decoder_init(struct decoder *decoder, struct frames *frames, TCPsocket video_socket) {
+    decoder->frames = frames;
+    decoder->video_socket = video_socket;
+}
+
 SDL_bool decoder_start(struct decoder *decoder) {
     SDL_LogDebug(SDL_LOG_CATEGORY_APPLICATION, "Starting decoder thread");
 

app/src/decoder.h

@@ -13,6 +13,7 @@ struct decoder {
     SDL_mutex *mutex;
 };
 
+void decoder_init(struct decoder *decoder, struct frames *frames, TCPsocket video_socket);
 SDL_bool decoder_start(struct decoder *decoder);
 void decoder_stop(struct decoder *decoder);
 void decoder_join(struct decoder *decoder);

app/src/scrcpy.c

@@ -129,8 +129,7 @@ SDL_bool scrcpy(const char *serial, Uint16 local_port, Uint16 max_size, Uint32 b
         goto finally_destroy_server;
     }
 
-    decoder.frames = &frames;
-    decoder.video_socket = device_socket;
+    decoder_init(&decoder, &frames, device_socket);
 
     // now we consumed the header values, the socket receives the video stream
     // start the decoder