[FFmpeg-trac] #67(undetermined:new): grey images (and video) when using -ss

[FFmpeg]

#67: grey images (and video) when using -ss
--------------------------+--------------------------
 Reporter:  aphid         |        Type:  defect
   Status:  new           |    Priority:  normal
Component:  undetermined  |     Version:  unspecified
 Keywords:                |  Blocked By:
 Blocking:                |  Reproduced:  0
 Analyzed:  0             |
--------------------------+--------------------------
 I'm splitting mpeg2 video, as captured from a capture card (and will
 ultimately be applying some libavfilter stuff for trademark obfuscation,
 but that is peripheral to this report).  I've recently upgraded from
 ffmpeg that was probably 1.5 years or so old, and splitting fine both for
 still images and video, to git.  When creating images with -ss, output is
 solid grey unless -ss happens to fall exactly on a keyframe.  When
 creating video, it starts gray, transitions to gray+artifacts and then
 looks fine after the first keyframe.

 This appears to be the same issue referenced here:
 https://roundup.libav.org/issue2019

 Output for the following command/paste can be found here (content is
 public domain):  http://metavidstorage02.ucsc.edu/raw_mpeg2/imagedump/

 {{{

     ffmpeg -ss 10992 -i senate_proceeding_04-08-11.mpeg -t 10
 /video/metavid/raw_mpeg2/imagedump/img%d.jpg
     FFmpeg version git-N-29131-gf4bc923, Copyright (c) 2000-2011 the
 FFmpeg developers
       built on Apr 18 2011 12:22:16 with gcc 4.4.3
       configuration: --enable-gpl --enable-version3 --enable-nonfree
 --enable-postproc --enable-libfaac --enable-libopencore-amrnb --enable-
 libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264
 --enable-libxvid --enable-x11grab --enable-libvpx --enable-libfreetype
       libavutil    50. 40. 1 / 50. 40. 1
       libavcodec   52.119. 1 / 52.119. 1
       libavformat  52.108. 0 / 52.108. 0
       libavdevice  52.  4. 0 / 52.  4. 0
       libavfilter   1. 78. 0 /  1. 78. 0
       libswscale    0. 13. 0 /  0. 13. 0
       libpostproc  51.  2. 0 / 51.  2. 0
     [mpeg @ 0x13d0650] max_analyze_duration reached
     Input #0, mpeg, from 'senate_proceeding_04-08-11.mpeg':
       Duration: 18:47:49.66, start: 0.338522, bitrate: 6544 kb/s
         Stream #0.0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480
 [PAR 8:9 DAR 4:3], 8000 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
         Stream #0.1[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16, 224 kb/s
     Incompatible pixel format 'yuv420p' for codec 'mjpeg', auto-selecting
 format 'yuvj420p'
     [buffer @ 0x13d5490] w:720 h:480 pixfmt:yuv420p
     [ffsink @ 0x13d22b0] auto-inserting filter 'auto-inserted scaler 0'
 between the filter 'src' and the filter 'out'
     [scale @ 0x13d2590] w:720 h:480 fmt:yuv420p -> w:720 h:480
 fmt:yuvj420p flags:0xa0000004
     Output #0, image2, to '/video/metavid/raw_mpeg2/imagedump/img%d.jpg':
       Metadata:
         encoder         : Lavf52.108.0
         Stream #0.0: Video: mjpeg, yuvj420p, 720x480 [PAR 8:9 DAR 4:3],
 q=2-31, 200 kb/s, 90k tbn, 29.97 tbc
     Stream mapping:
       Stream #0.0 -> #0.0
     Press [q] to stop encoding
     [mpeg2video @ 0x13d3100] warning: first frame is no keyframe
     frame=  298 fps= 52 q=24.8 Lsize=      -0kB time=9.94 bitrate=
 -0.0kbits/s dup=3 drop=0
     video:5531kB audio:0kB global headers:0kB muxing overhead -100.000388%
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/67>
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