Cool_Tools/vgmstream
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ffmpeg looping: allow compile with accurate (slower?) looping + document

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bnnm 2016-11-20 15:51:02 +01:00
parent 729658a19c
commit ec068700ae
1 changed files with 17 additions and 1 deletions
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18
src/vgmstream.c
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@ -1791,6 +1791,10 @@ int vgmstream_do_loop(VGMSTREAM * vgmstream) {
if (vgmstream->coding_type==coding_FFmpeg) {
ffmpeg_codec_data *data = (ffmpeg_codec_data *)(vgmstream->codec_data);
int64_t ts;
/* Seek to loop start by timestamp (closest frame) + adjust skipping some samples */
/* FFmpeg seeks by ts by design (since not all containers can accurately skip to a frame). */
/* TODO: this seems to be off by +-1 frames in some cases */
ts = vgmstream->loop_start_sample;
if (ts >= data->sampleRate * 2) {
data->samplesToDiscard = data->sampleRate * 2;
@ -1802,14 +1806,26 @@ int vgmstream_do_loop(VGMSTREAM * vgmstream) {
}
data->framesRead = (int)ts;
ts = data->framesRead * (data->formatCtx->duration) / data->totalFrames;
#ifdef VGM_USE_FFMPEG_ACCURATE_LOOPING
/* Start from 0 and discard samples until loop_start for accurate looping (slower but not too noticeable) */
/* We could also seek by offset (AVSEEK_FLAG_BYTE) to the frame closest to the loop then discard
* some samples, which is fast but would need calculations per format / when frame size is not constant */
data->samplesToDiscard = vgmstream->loop_start_sample;
data->framesRead = 0;
ts = 0;
#endif /* VGM_USE_FFMPEG_ACCURATE_LOOPING */
avformat_seek_file(data->formatCtx, -1, ts - 1000, ts, ts, AVSEEK_FLAG_ANY);
avcodec_flush_buffers(data->codecCtx);
data->readNextPacket = 1;
data->bytesConsumedFromDecodedFrame = INT_MAX;
data->endOfStream = 0;
data->endOfAudio = 0;
}
#endif
#endif /* VGM_USE_FFMPEG */
#if defined(VGM_USE_MP4V2) && defined(VGM_USE_FDKAAC)
if (vgmstream->coding_type==coding_MP4_AAC) {
mp4_aac_codec_data *data = (mp4_aac_codec_data *)(vgmstream->codec_data);