Give a name to decoder instances

This will be useful in logs.

PR #3757 <https://github.com/Genymobile/scrcpy/pull/3757>

app/src/decoder.c

@@ -48,7 +48,7 @@ sc_decoder_open(struct sc_decoder *decoder, const AVCodec *codec) {
     decoder->codec_ctx->flags |= AV_CODEC_FLAG_LOW_DELAY;
 
     if (avcodec_open2(decoder->codec_ctx, codec, NULL) < 0) {
-        LOGE("Could not open codec");
+        LOGE("Decoder '%s': could not open codec", decoder->name);
         avcodec_free_context(&decoder->codec_ctx);
         return false;
     }
@@ -101,7 +101,8 @@ sc_decoder_push(struct sc_decoder *decoder, const AVPacket *packet) {
 
     int ret = avcodec_send_packet(decoder->codec_ctx, packet);
     if (ret < 0 && ret != AVERROR(EAGAIN)) {
-        LOGE("Could not send video packet: %d", ret);
+        LOGE("Decoder '%s': could not send video packet: %d",
+             decoder->name, ret);
         return false;
     }
     ret = avcodec_receive_frame(decoder->codec_ctx, decoder->frame);
@@ -114,7 +115,8 @@ sc_decoder_push(struct sc_decoder *decoder, const AVPacket *packet) {
 
         av_frame_unref(decoder->frame);
     } else if (ret != AVERROR(EAGAIN)) {
-        LOGE("Could not receive video frame: %d", ret);
+        LOGE("Decoder '%s', could not receive video frame: %d",
+             decoder->name, ret);
         return false;
     }
     return true;
@@ -140,7 +142,8 @@ sc_decoder_packet_sink_push(struct sc_packet_sink *sink,
 }
 
 void
-sc_decoder_init(struct sc_decoder *decoder) {
+sc_decoder_init(struct sc_decoder *decoder, const char *name) {
+    decoder->name = name; // statically allocated
     decoder->sink_count = 0;
 
     static const struct sc_packet_sink_ops ops = {

app/src/decoder.h

@@ -14,6 +14,8 @@
 struct sc_decoder {
     struct sc_packet_sink packet_sink; // packet sink trait
 
+    const char *name; // must be statically allocated (e.g. a string literal)
+
     struct sc_frame_sink *sinks[SC_DECODER_MAX_SINKS];
     unsigned sink_count;
 
@@ -21,8 +23,9 @@ struct sc_decoder {
     AVFrame *frame;
 };
 
+// The name must be statically allocated (e.g. a string literal)
 void
-sc_decoder_init(struct sc_decoder *decoder);
+sc_decoder_init(struct sc_decoder *decoder, const char *name);
 
 void
 sc_decoder_add_sink(struct sc_decoder *decoder, struct sc_frame_sink *sink);

app/src/scrcpy.c

@@ -441,7 +441,7 @@ scrcpy(struct scrcpy_options *options) {
     needs_video_decoder |= !!options->v4l2_device;
 #endif
     if (needs_video_decoder) {
-        sc_decoder_init(&s->video_decoder);
+        sc_decoder_init(&s->video_decoder, "video");
         sc_demuxer_add_sink(&s->video_demuxer, &s->video_decoder.packet_sink);
     }