[FFmpeg-trac] #735(FFmpeg:new): Incorrect DTS sync in OGG codec
FFmpeg
trac at avcodec.org
Mon Dec 12 14:27:08 CET 2011
#735: Incorrect DTS sync in OGG codec
-------------------------------------+-------------------------------------
Reporter: zvi | Type: defect
Status: new | Priority: important
Component: FFmpeg | Version: 0.8.7
Keywords: ffmpeg ogv | Blocked By:
sync | Reproduced by developer: 0
Blocking: |
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Hi,
I've noticed incorrect DTS values in OGG encoded audio streams (as part of
an OGV file). This happened with a ffmpeg-0.8.7
These are the steps I have taken to reproduce it.
1. Convert a valid and working MP4 (h264/aac) as confirmed by ffprobe to
an OGV file using:
{{{
ffmpeg -y -i vid.mp4 -vcodec libtheora -b 1000k -acodec libvorbis -ab 192k
vid.ogv
}}}
2. Probing the "vid.ogv" file using ffprobe shows that during audio
frames, the "pos" doesn't change - even for the video frames it seems to
repeat ~10 times. See simplified format dump below.
3. While "vid.ogv" plays ok in VLC, after doing a zero transformation on
it, it breaks completely and audio goes totally out of sync (video plays
ok).
{{{
ffmpeg -y -i vid.ogv -vcodec copy -acodec copy new_vid.ogv
}}}
4. The '''new_vid.ogv''' file no longer plays correctly. Putting some
debug prints in ffmpeg.c:output_packet(...) I see the following.[[BR]]
A sequence of consecutive audio frames gets the correct DTS values. From 0
to 10941 in steps of ~64.[[BR]]
Then there is a sequence of consecutive video frames. For video the DTS
always appears to be correct.[[BR]]
The next sequence of consecutive audio frames now starts at 154048 -
instead of being at ~11005[[BR]]
Also notice the negative '''duration''' value.
{{{
Input #0, ogg, from 'new_vid.ogv':
Duration: -513359:-56:-35.41, start: 0.000000, bitrate: N/A
Stream #0.0: Video: theora, yuv420p, 960x540 [PAR 1:1 DAR 16:9], 29.97
tbr, 29.97 tbn, 29.97 tbc
Stream #0.1: Audio: vorbis, 48000 Hz, stereo, s16, 192 kb/s
}}}
If you need any additional information, please let me know.
Thanks,
TR
{{{
type=video index=0 dts=0 dts_time=0.000000 [100/2997] duration=1 pos=7414
type=video index=0 dts=1 dts_time=0.033367 [100/2997] duration=1 pos=7414
type=video index=0 dts=2 dts_time=0.066733 [100/2997] duration=1 pos=7414
type=video index=0 dts=3 dts_time=0.100100 [100/2997] duration=1 pos=7414
...
type=video index=0 dts=83 dts_time=2.769436 [100/2997] duration=1
pos=260411
type=audio index=1 dts=0 dts_time=0.000000 [1/48000] duration=0
pos=323479
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=323479
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=323479
...
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=323479
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=323479
type=video index=0 dts=84 dts_time=2.802803 [100/2997] duration=1
pos=260411
type=video index=0 dts=85 dts_time=2.836170 [100/2997] duration=1
pos=355961
type=video index=0 dts=86 dts_time=2.869536 [100/2997] duration=1
pos=355961
type=video index=0 dts=87 dts_time=2.902903 [100/2997] duration=1
pos=355961
type=video index=0 dts=88 dts_time=2.936270 [100/2997] duration=1
pos=355961
type=video index=0 dts=89 dts_time=2.969636 [100/2997] duration=1
pos=355961
type=video index=0 dts=90 dts_time=3.003003 [100/2997] duration=1
pos=355961
type=video index=0 dts=91 dts_time=3.036370 [100/2997] duration=1
pos=355961
type=video index=0 dts=92 dts_time=3.069736 [100/2997] duration=1
pos=355961
type=video index=0 dts=93 dts_time=3.103103 [100/2997] duration=1
pos=355961
type=video index=0 dts=94 dts_time=3.136470 [100/2997] duration=1
pos=355961
type=video index=0 dts=95 dts_time=3.169837 [100/2997] duration=1
pos=355961
type=video index=0 dts=96 dts_time=3.203203 [100/2997] duration=1
pos=355961
type=video index=0 dts=97 dts_time=3.236570 [100/2997] duration=1
pos=355961
type=video index=0 dts=98 dts_time=3.269937 [100/2997] duration=1
pos=419330
type=video index=0 dts=99 dts_time=3.303303 [100/2997] duration=1
pos=419330
type=video index=0 dts=100 dts_time=3.336670 [100/2997] duration=1
pos=419330
type=video index=0 dts=101 dts_time=3.370037 [100/2997] duration=1
pos=419330
type=video index=0 dts=102 dts_time=3.403403 [100/2997] duration=1
pos=419330
type=video index=0 dts=103 dts_time=3.436770 [100/2997] duration=1
pos=419330
type=video index=0 dts=104 dts_time=3.470137 [100/2997] duration=1
pos=419330
type=video index=0 dts=105 dts_time=3.503504 [100/2997] duration=1
pos=419330
...
type=video index=0 dts=148 dts_time=4.938272 [100/2997] duration=1
pos=545023
type=audio index=1 dts=154048 dts_time=3.209333 [1/48000] duration=0
pos=608173
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=608173
type=audio index=1 dts=N/A dts_time=N/A [1/48000] duration=0 pos=608173
}}}
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/735>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker
More information about the FFmpeg-trac
mailing list