[FFmpeg-user] warning: first frame is no keyframe

[tank pranav]

when ever any video you decode , if that video starts with partial GOP then its not possible to decode that kind of GOP. Take an example of let's say , if any video starts with B or P frame then this kind of frames are not possible to decode that is why ffmpeg is giving gray frames.

Now what is the solution of that , you start decoding you video when u encounter first I frame. so from there after , you will get whole frames proper. ( thati s done by dvbcut software , if you are not aware about this software then try once by downloading it ).




________________________________
 From: Shaily Athghara <shaily.athghara at gmail.com>
To: ffmpeg-user at ffmpeg.org 
Sent: Wednesday, April 11, 2012 4:11 PM
Subject: [FFmpeg-user] warning: first frame is no keyframe
 
Thanks Carl,

After executing the following command

./ffmpeg -r 6.5 -f h263 -i 1.raw -i 4.wav -y -f flv -ar 11025 output.flv

It outputs the correct number of frames (frame=189) but started giving the
same warning

"warning: first frame is no keyframe" and the initial frame are grayed out.

./ffmpeg -r 6.5 -f h263 -i 1.raw -i 4.wav -y -f flv -ar 11025 output.flv
ffmpeg version 0.10.2.git Copyright (c) 2000-2012 the FFmpeg developers
  built on Apr 11 2012 07:33:31 with gcc 4.1.2 20080704 (Red Hat 4.1.2-44)
  configuration:
  libavutil      51. 46.100 / 51. 46.100
  libavcodec     54. 14.101 / 54. 14.101
  libavformat    54.  3.100 / 54.  3.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 67.101 /  2. 67.101
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 10.100 /  0. 10.100
[h263 @ 0x1cdac20] warning: first frame is no keyframe
[h263 @ 0x1ccc4e0] max_analyze_duration 5000000 reached at 5005000
[h263 @ 0x1ccc4e0] Estimating duration from bitrate, this may be inaccurate
Input #0, h263, from '1.raw':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h263, yuv420p, 352x288 [SAR 12:11 DAR 4:3], 29.97
fps, 29.97 tbr, 1200k tbn, 29.97 tbc
[wav @ 0x1e89be0] max_analyze_duration 5000000 reached at 5120000
Input #1, wav, from '4.wav':
  Duration: 00:00:13.68, bitrate: 64 kb/s
    Stream #1:0: Audio: pcm_alaw ([6][0][0][0] / 0x0006), 8000 Hz, 1
channels, s16, 64 kb/s
[buffer @ 0x1cdb3e0] w:352 h:288 pixfmt:yuv420p tb:1/1000000 sar:12/11
sws_param:flags=2
Output #0, flv, to 'output.flv':
  Metadata:
    encoder         : Lavf54.3.100
    Stream #0:0: Video: flv1 ([2][0][0][0] / 0x0002), yuv420p, 352x288 [SAR
12:11 DAR 4:3], q=2-31, 200 kb/s, 1k tbn, 29.97 tbc
    Stream #0:1: Audio: adpcm_swf ([1][0][0][0] / 0x0001), 11025 Hz, 1
channels, s16, 44 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (h263 -> flv)
  Stream #1:0 -> #0:1 (pcm_alaw -> adpcm_swf)
Press [q] to stop, [?] for help
[h263 @ 0x1cdac20] warning: first frame is no keyframe
[h263 @ 0x1cdac20] concealing 308 DC, 308 AC, 308 MV errors
frame=  189 fps=0.0 q=7.5 Lsize=     342kB time=00:00:06.43 bitrate=
434.6kbits/s
video:259kB audio:75kB global headers:0kB muxing overhead 2.359965%

I tried the next option as well renaming 1.raw to 1.h263 but this also
gives the same output.
Also notice some more messages like "max_analyze_duration 5000000 reached
at 5005000" and " Estimating duration from bitrate, this may be
inaccurate"  not sure whether these are errors or just info messages.
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