On Mon, May 9, 2022 at 11:19 AM Guangyu Sun <sunguangy...@gmail.com> wrote:
> On Thu, May 5, 2022 at 4:05 PM Guangyu Sun <sunguangy...@gmail.com> wrote: > >> The decoded Data is not returned from the first frame; it must be used >> to 'prime' the decode engine. The duration of the first packet should >> be ignored also by the container, to make sure the total duration is >> trimmed correctly. >> >> If the file has multiple pages for the data packets. The duration of the >> last packet can be correctly adjusted without being affected by the first >> packet. But if the first packet and the last packet are located in the >> same page, the duration of the last packet will have an unwanted offset. >> >> This commit fixes https://trac.ffmpeg.org/ticket/6367. >> >> dd if=/dev/zero of=./silence.raw count=1 bs=500 >> oggenc --raw silence.raw --output=silence.ogg >> oggdec --raw --output silence.oggdec.raw silence.ogg >> ffmpeg -codec:a libvorbis -i silence.ogg -f s16le -codec:a pcm_s16le >> silence.libvorbis.ffmpeg.raw >> ffmpeg -i silence.ogg -f s16le -codec:a pcm_s16le >> silence.native.ffmpeg.raw >> ls -l *.raw >> >> Signed-off-by: Guangyu Sun <g...@roblox.com> >> --- >> libavformat/oggparsevorbis.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/libavformat/oggparsevorbis.c b/libavformat/oggparsevorbis.c >> index 289900f7cf..9a486c9fe8 100644 >> --- a/libavformat/oggparsevorbis.c >> +++ b/libavformat/oggparsevorbis.c >> @@ -412,6 +412,7 @@ static int vorbis_packet(AVFormatContext *s, int idx) >> struct ogg_stream *os = ogg->streams + idx; >> struct oggvorbis_private *priv = os->private; >> int duration, flags = 0; >> + int first_page; >> >> if (!priv->vp) >> return AVERROR_INVALIDDATA; >> @@ -420,7 +421,8 @@ static int vorbis_packet(AVFormatContext *s, int idx) >> * here we parse the duration of each packet in the first page and >> compare >> * the total duration to the page granule to find the encoder delay >> and >> * set the first timestamp */ >> - if ((!os->lastpts || os->lastpts == AV_NOPTS_VALUE) && !(os->flags & >> OGG_FLAG_EOS) && (int64_t)os->granule>=0) { >> + first_page = !os->lastpts || os->lastpts == AV_NOPTS_VALUE; >> + if (first_page && !(os->flags & OGG_FLAG_EOS) && >> (int64_t)os->granule>=0) { >> int seg, d; >> uint8_t *last_pkt = os->buf + os->pstart; >> uint8_t *next_pkt = last_pkt; >> @@ -479,6 +481,13 @@ static int vorbis_packet(AVFormatContext *s, int idx) >> flags = 0; >> } >> os->pduration = duration; >> + /* Data is not returned from the first frame; it must be used to >> 'prime' >> + * the decode engine. The duration of the first packet should be >> ignored >> + * also by the container, to make sure the total duration is >> trimmed >> + * correctly. >> + */ >> + if (first_page && os->segp == 1) >> + os->pduration = 0; >> } >> >> /* final packet handling >> -- >> 2.30.1 >> >> > Ping. > Ping again. This patch fixes an oggvorbis transcode issue. https://devforum.roblox.com/t/recent-changes-to-uploaded-audio-compressionprocessing-causing-timing-drift/1735440/10 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
