[FFmpeg-user] Screencast produces only gray output

[look at ebookring.net]

On 2012-11-19 05:09, Carl Eugen Hoyos wrote:
> <look <at> ebookring.net> writes:
>
>> ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 20 -s 1280x800
>> -i :0.0 -acodec pcm_s16le -vcodec libx264 -preset ultrafast
>> -crf 0 -threads 0 output.mkv
>
> If you don't want us to guess, please provide complete,
> uncut console output.
>
> If you'd like a guess, add -pix_fmt yuv420p.
> (Your original output file plays fine, your playback
> application is buggy / misses features.)
>
> Carl Eugen

Whoops....minor correction- the previous code was using our suggestion 
of the -pix, etc. While you idea worked very well, when watching the 
file it produces what looks like "fast motion" (everyone walking faster 
than reality).


Here's the original code I used that produces the gray screen;

$ ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 10 -s 1280x800 -i :0.0 
-acodec pcm_s16le -vcodec libx264 -preset ultrafast -crf 0 -threads 0 
output.mkv
ffmpeg version N-42139-g7693543 Copyright (c) 2000-2012 the FFmpeg 
developers
   built on Nov  8 2012 22:15:12 with gcc 4.4.3 (Ubuntu 
4.4.3-4ubuntu5.1)
   configuration: --enable-gpl --enable-libfaac --enable-libmp3lame 
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora 
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree 
--enable-version3 --enable-x11grab
   libavutil      52.  5.100 / 52.  5.100
   libavcodec     54. 71.100 / 54. 71.100
   libavformat    54. 36.100 / 54. 36.100
   libavdevice    54.  3.100 / 54.  3.100
   libavfilter     3. 21.106 /  3. 21.106
   libswscale      2.  1.102 /  2.  1.102
   libswresample   0. 16.100 /  0. 16.100
   libpostproc    52.  1.100 / 52.  1.100
[alsa @ 0x98b1580] Estimating duration from bitrate, this may be 
inaccurate
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, alsa, from 'pulse':
   Duration: N/A, start: 1353329961.841793, bitrate: 1536 kb/s
     Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
[x11grab @ 0x98aebc0] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 
1280 height: 800
[x11grab @ 0x98aebc0] shared memory extension found
[x11grab @ 0x98aebc0] Estimating duration from bitrate, this may be 
inaccurate
Input #1, x11grab, from ':0.0':
   Duration: N/A, start: 1353329962.074573, bitrate: 327680 kb/s
     Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x800, 
327680 kb/s, 10 tbr, 1000k tbn, 10 tbc
File 'output.mkv' already exists. Overwrite ? [y/N] y
using cpu capabilities: MMX2 SSE2Slow SlowCTZ
[libx264 @ 0x98a9500] profile High 4:4:4 Predictive, level 3.2, 4:4:4 
8-bit
[libx264 @ 0x98a9500] 264 - core 129 r16 1cffe9f - H.264/MPEG-4 AVC 
codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - 
options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 
mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 
deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=1 
lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 
bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 
keyint_min=10 scenecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
Output #0, matroska, to 'output.mkv':
   Metadata:
     encoder         : Lavf54.36.100
     Stream #0:0: Video: h264, yuv444p, 1280x800, q=-1--1, 1k tbn, 10 
tbc
     Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Stream mapping:
   Stream #1:0 -> #0:0 (rawvideo -> libx264)
   Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le)
Press [q] to stop, [?] for help
frame=  104 fps=5.2 q=0.0 Lsize=    7798kB time=00:00:10.40 
bitrate=6142.3kbits/s
video:5851kB audio:1894kB subtitle:0 global headers:0kB muxing overhead 
0.686932%
[libx264 @ 0x98a9500] frame I:1     Avg QP: 0.00  size:455131
[libx264 @ 0x98a9500] frame P:103   Avg QP: 0.00  size: 53741
[libx264 @ 0x98a9500] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x98a9500] mb P  I16..4:  4.1%  0.0%  0.0%  P16..4:  6.1%  
0.0%  0.0%  0.0%  0.0%    skip:89.8%
[libx264 @ 0x98a9500] coded y,u,v intra: 49.2% 44.6% 45.1% inter: 4.5% 
3.6% 3.8%
[libx264 @ 0x98a9500] i16 v,h,dc,p: 61% 39%  0%  0%
[libx264 @ 0x98a9500] kb/s:4608.05




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