GBA: Add postAudioBuffer callback

src/gba/audio.c

@@ -822,10 +822,15 @@ static void _sample(struct GBAAudio* audio) {
 	}
 	produced = blip_samples_avail(audio->left);
 #endif
-	if (audio->p->stream) {
+	if (audio->p->stream && audio->p->stream->postAudioFrame) {
 		audio->p->stream->postAudioFrame(audio->p->stream, sampleLeft, sampleRight);
 	}
-	GBASyncProduceAudio(audio->p->sync, produced >= audio->samples);
+	bool wait = produced >= audio->samples;
+	GBASyncProduceAudio(audio->p->sync, wait);
+
+	if (wait && audio->p->stream && audio->p->stream->postAudioBuffer) {
+		audio->p->stream->postAudioBuffer(audio->p->stream, audio);
+	}
 }
 
 void GBAAudioSerialize(const struct GBAAudio* audio, struct GBASerializedState* state) {

src/gba/gba.h

@@ -99,6 +99,7 @@ typedef void (*GBALogHandler)(struct GBAThread*, enum GBALogLevel, const char* f
 struct GBAAVStream {
 	void (*postVideoFrame)(struct GBAAVStream*, struct GBAVideoRenderer* renderer);
 	void (*postAudioFrame)(struct GBAAVStream*, int16_t left, int16_t right);
+	void (*postAudioBuffer)(struct GBAAVStream*, struct GBAAudio*);
 };
 
 struct GBATimer {

src/platform/ffmpeg/ffmpeg-encoder.c

@@ -33,6 +33,7 @@ void FFmpegEncoderInit(struct FFmpegEncoder* encoder) {
 
 	encoder->d.postVideoFrame = _ffmpegPostVideoFrame;
 	encoder->d.postAudioFrame = _ffmpegPostAudioFrame;
+	encoder->d.postAudioBuffer = 0;
 
 	encoder->audioCodec = 0;
 	encoder->videoCodec = 0;

src/platform/imagemagick/imagemagick-gif-encoder.c

@@ -15,6 +15,7 @@ void ImageMagickGIFEncoderInit(struct ImageMagickGIFEncoder* encoder) {
 
 	encoder->d.postVideoFrame = _magickPostVideoFrame;
 	encoder->d.postAudioFrame = _magickPostAudioFrame;
+	encoder->d.postAudioBuffer = 0;
 
 	encoder->frameskip = 2;
 }