[FFmpeg-trac] #2592(avcodec:new): Bug with b-frames?

[FFmpeg]

#2592: Bug with b-frames?
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             Reporter:  microchip   |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  important   |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  regression  |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by microchip):

 Hi Carl,

 Thanks for the response. It produces a valid output but it's of low
 quality compared to the output of 1.2.1. I contribute this to the 0
 entries for b-frames (in: 0 and out: 0) in the log file I attached for the
 git version. When I say low quality, I mean that I can see blocks all over
 the place while when using 1.2.1 this is not the case. I no longer have
 the film I used when I noticed this problem so I tried on a sample here
 and the problem is the same.

 About the bitrate, in 1.2.1 when using 4600k as bitrate, the second pass
 would go up to 3000k while the git ffmpeg will go just over 1600k. That's
 a pretty big difference between the two versions

 The second pass output for the sample I tried is as follows:

 {{{
 ffmpeg version N-53304-g2187600 Copyright (c) 2000-2013 the FFmpeg
 developers
   built on May 20 2013 19:53:33 with gcc 4.7 (SUSE Linux)
   configuration: --enable-shared --enable-gpl --enable-version3 --enable-
 libx264 --enable-libxvid --enable-libmp3lame --enable-avresample
 --prefix=/home/neutrino/local
   libavutil      52. 33.100 / 52. 33.100
   libavcodec     55. 10.101 / 55. 10.101
   libavformat    55.  7.100 / 55.  7.100
   libavdevice    55.  1.100 / 55.  1.100
   libavfilter     3. 68.101 /  3. 68.101
   libavresample   1.  1.  0 /  1.  1.  0
   libswscale      2.  3.100 /  2.  3.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  3.100 / 52.  3.100
 [mpeg @ 0xff89c0] max_analyze_duration 5000000 reached at 5000000
 microseconds
 Guessed Channel Layout for  Input Stream #0.1 : stereo
 Input #0, mpeg, from '/home/neutrino/file2dvd/jlo/tmp22404.mpg':
   Duration: 00:05:12.91, start: 0.280000, bitrate: 8234 kb/s
     Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [SAR
 16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
     Stream #0:1[0xa0]: Audio: pcm_s16be, 48000 Hz, stereo, s16, 1536 kb/s
 [mpeg2video @ 0xffaa20] [lavc rc] Using all of requested bitrate is not
 necessary for this video with these parameters.
 [dvd @ 0xffa140] VBV buffer size not set, muxing may fail
 Output #0, dvd, to '/home/neutrino/file2dvd/jlo/jlo.mpg':
   Metadata:
     encoder         : Lavf55.7.100
     Stream #0:0: Video: mpeg2video, yuv420p, 720x576 [SAR 16:15 DAR 4:3],
 q=2-31, pass 2, 8000 kb/s, 90k tbn, 25 tbc
     Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (mpeg2video -> mpeg2video)
   Stream #0:1 -> #0:1 (pcm_s16be -> ac3)
 Press [q] to stop, [?] for help
 [mpeg2video @ 0xff9340] warning: first frame is no keyframe
     Last message repeated 1 times
 }}}

 How to reproduce: just compile latest git and use -bf 2 for encoding. Then
 look at the log file and you'll see that all "type: 3" entries have "in:
 0" and "out: 0" entries. Then look at the output file and you'll see
 blocks all over the place. At least this is the case here when comparing
 to the 1.2.1 version

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2592#comment:2>
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