[FFmpeg-trac] #3965(avcodec:new): Non-sense best effort timestamp

FFmpeg trac at avcodec.org
Sat Sep 20 13:18:46 CEST 2014


#3965: Non-sense best effort timestamp
---------------------------------+---------------------------------------
             Reporter:  gjdfgh   |                     Type:  defect
               Status:  new      |                 Priority:  normal
            Component:  avcodec  |                  Version:  unspecified
             Keywords:           |               Blocked By:
             Blocking:           |  Reproduced by developer:  0
Analyzed by developer:  0        |
---------------------------------+---------------------------------------
 Summary of the bug:

 As you can see below, mp3 files which set skip_samples yield inconsistent
 best_effort_timestamp values for the first and second frames.

 The first frame has a duration of 0.001066 seconds, but if you subtract
 the best effort timestamps of the second and first frame, you get
 0.026122, a much higher value. Obviously the first frame's
 best_effort_timestamp is broken. It should have the same value as pkt_pts.

 Also, I would argue that the first timestamp should be 0 (i.e. libavcodec
 shouldn't adjust the packet timestamp by the skip_samples amount), but
 that's a different issue.

 How to reproduce:
 {{{
 % ffprobe test.mp3 -show_frames
 [FRAME]
 media_type=audio
 key_frame=1
 pkt_pts=353600
 pkt_pts_time=0.025057
 pkt_dts=353600
 pkt_dts_time=0.025057
 best_effort_timestamp=0
 best_effort_timestamp_time=0.000000
 pkt_duration=15040
 pkt_duration_time=0.001066
 pkt_pos=417
 pkt_size=417
 sample_fmt=s16p
 nb_samples=47
 channels=2
 channel_layout=stereo
 [/FRAME]
 [FRAME]
 media_type=audio
 key_frame=1
 pkt_pts=368640
 pkt_pts_time=0.026122
 pkt_dts=368640
 pkt_dts_time=0.026122
 best_effort_timestamp=368640
 best_effort_timestamp_time=0.026122
 pkt_duration=368640
 pkt_duration_time=0.026122
 pkt_pos=834
 pkt_size=418
 sample_fmt=s16p
 nb_samples=1152
 channels=2
 channel_layout=stereo
 [/FRAME]
 }}}
 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3965>
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