[FFmpeg-trac] #3678(avcodec:new): Regressions in the video duration/bitrate report

[FFmpeg]

#3678: Regressions in the video duration/bitrate report
------------------------------------+-----------------------------------
             Reporter:  Malizor     |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+-----------------------------------

Comment (by Malizor):

 Replying to [comment:3 cehoyos]:
 > Replying to [comment:2 Malizor]:
 >
 > > The full video file is 40G and is 1h 26mn long.

 Sorry, in fact it is truly 1:48:31 long (as verified by playing the video
 in VLC 2.0.8)


 > Does this really imply ~50Mb/s? Doesn't sound correct to me.
 > How does old {{{ffmpeg -i}}} look for your complete 40G sample?

 0.10.10 (good estimation):

 {{{
 ffmpeg -i ~/file_1_VR_16_PCBD_1.mxf
 ffmpeg version 0.10.10 Copyright (c) 2000-2013 the FFmpeg developers
   built on May 28 2014 11:23:04 with gcc 4.8.1
   configuration:
   libavutil      51. 35.100 / 51. 35.100
   libavcodec     53. 61.100 / 53. 61.100
   libavformat    53. 32.100 / 53. 32.100
   libavdevice    53.  4.100 / 53.  4.100
   libavfilter     2. 61.100 /  2. 61.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0.  6.100 /  0.  6.100
 [mxf @ 0x29843a0] Estimating duration from bitrate, this may be inaccurate
 Input #0, mxf, from '/home/malizor/1078554_1_VR_16_PCBD_1.mxf':
   Duration: 01:48:31.68, start: 0.000000, bitrate: 49999 kb/s
     Stream #0:0: Video: mpeg2video (4:2:2), yuv422p, 720x608 [SAR 152:135
 DAR 4:3], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
     Stream #0:1: Audio: pcm_s24le, 48000 Hz, 8 channels, s32, 9216 kb/s
 At least one output file must be specified
 }}}

 1.0 (estimation a bit too short):

 {{{
 ffmpeg -i ~/file_1_VR_16_PCBD_1.mxf
 ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
   built on May 27 2014 17:07:38 with gcc 4.8 (Ubuntu/Linaro
 4.8.1-10ubuntu9)
   configuration:
   libavutil      51. 73.101 / 51. 73.101
   libavcodec     54. 59.100 / 54. 59.100
   libavformat    54. 29.104 / 54. 29.104
   libavdevice    54.  2.101 / 54.  2.101
   libavfilter     3. 17.100 /  3. 17.100
   libswscale      2.  1.101 /  2.  1.101
   libswresample   0. 15.100 /  0. 15.100
 [mxf @ 0x1d50240] Estimating duration from bitrate, this may be inaccurate
 Guessed Channel Layout for  Input Stream #0.1 : 7.1
 Input #0, mxf, from '/home/malizor/file_1_VR_16_PCBD_1.mxf':
   Metadata:
     timecode        : 10:00:00:01
   Duration: 01:31:38.24, start: 0.000000, bitrate: 59215 kb/s
     Stream #0:0: Video: mpeg2video (4:2:2), yuv422p, 720x608 [SAR 152:135
 DAR 4:3], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
     Stream #0:1: Audio: pcm_s24le, 48000 Hz, 7.1, s32, 9216 kb/s
 At least one output file must be specified
 }}}

 HEAD (estimation way too big):

 {{{
 ffmpeg -i ~/file_1_VR_16_PCBD_1.mxf
 ffmpeg version N-63469-g5863207 Copyright (c) 2000-2014 the FFmpeg
 developers
   built on May 27 2014 16:20:47 with gcc 4.8 (Ubuntu/Linaro
 4.8.1-10ubuntu9)
   configuration:
   libavutil      52. 87.100 / 52. 87.100
   libavcodec     55. 65.100 / 55. 65.100
   libavformat    55. 41.100 / 55. 41.100
   libavdevice    55. 13.101 / 55. 13.101
   libavfilter     4.  5.100 /  4.  5.100
   libswscale      2.  6.100 /  2.  6.100
   libswresample   0. 19.100 /  0. 19.100
 [mxf @ 0x3156ae0] Estimating duration from bitrate, this may be inaccurate
 Guessed Channel Layout for  Input Stream #0.1 : 7.1
 Input #0, mxf, from '/home/malizor/file_1_VR_16_PCBD_1.mxf':
   Metadata:
     application_platform: Omneon Media Api (mqx)
     uid             : 98a72bb5-4bba-e111-92d9-00d0280f7410
     generation_uid  : aca72bb5-4bba-e111-bc13-00d0280f7410
     company_name    : Omneon Inc.
     product_name    : Omneon Media Subsystem
     modification_date: 2012-06-19 20:16:52
     product_version : 6.3.1.0.release
     product_uid     : 00000000-0000-0010-8000-050e0b010602
     timecode        : 10:00:00:01
   Duration: 09:48:48.04, start: 0.000000, bitrate: 9215 kb/s
     Stream #0:0: Video: mpeg2video (4:2:2), yuv422p(tv), 720x608 [SAR
 152:135 DAR 4:3], max. 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
     Stream #0:1: Audio: pcm_s24le, 48000 Hz, 7.1, s32, 9216 kb/s
 At least one output file must be specified
 }}}

 > > New versions of ffmpeg detect it as being 9h 48m long
 > And a warning is shown that this value is maybe incorrect.

 Indeed.
 So the problem is that the estimation was better in older versions.

 > > I understand what you say about the bitrate, but it's sure that it is
 truly higher than the detected 9118 kb/s.
 >
 > Of course.
 > The bitrate of the file is unknown / wrong because the video stream
 doesn't store a bitrate.

 Apparently somthing changed in the way ffmpeg try to guess the bitrate,
 and it has regressed for some videos like this one.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3678#comment:4>
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