[FFmpeg-user] Screencast produces only gray output

Tue Nov 20 13:31:16 CET 2012

On 2012-11-20 05:18, look at ebookring.net wrote:
> On 2012-11-20 02:54, Carl Eugen Hoyos wrote:
>> <look <at> ebookring.net> writes:
>>
>>> $ ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 10 -s 1280x800
>>> -i :0.0 -acodec pcm_s16le -vcodec libx264 -pix_fmt yuv420p
>>> -preset ultrafast -crf 0 -threads 0 output.mkv
>>
>>> frame=  230 fps=7.1 q=0.0 Lsize=   10363kB time=00:00:23.00
>>                  _^_
>>
>> This looks very suspicious, please try with a significantly
>> lower resolution or -r 5.
>>
>> Carl Eugen
>>
>
>
> Here's the result; (no audio is captured but the video is acceptable
> and will play with FFplay, VLC & Totem
>

The audio problem has been fixed- that is I had to set Ubuntu sound 
options as Analog Stereo Output.

>
>
> $ ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 5 -s 1280x800 -i :0.0
> -acodec pcm_s16le -vcodec libx264 -pix_fmt yuv420p -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 @ 0xae5d580] 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: 1353413584.631743, bitrate: 1536 kb/s
>     Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
> [x11grab @ 0xae5abc0] device: :0.0 -> display: :0.0 x: 0 y: 0 width:
> 1280 height: 800
> [x11grab @ 0xae5abc0] shared memory extension found
> [x11grab @ 0xae5abc0] Estimating duration from bitrate, this may be
> inaccurate
> Input #1, x11grab, from ':0.0':
>   Duration: N/A, start: 1353413584.845664, bitrate: 163840 kb/s
>     Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x800,
> 163840 kb/s, 5 tbr, 1000k tbn, 5 tbc
> File 'output.mkv' already exists. Overwrite ? [y/N] y
> using cpu capabilities: MMX2 SSE2Slow SlowCTZ
> [libx264 @ 0xae55820] profile High 4:4:4 Predictive, level 3.2, 4:2:0 
> 8-bit
> [libx264 @ 0xae55820] 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=5 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, yuv420p, 1280x800, q=-1--1, 1k tbn, 5 
> 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=  345 fps=5.1 q=0.0 Lsize=   55203kB time=00:01:09.82
> bitrate=6477.0kbits/s
> video:41749kB audio:13091kB subtitle:0 global headers:0kB muxing
> overhead 0.663149%
> [libx264 @ 0xae55820] frame I:2     Avg QP: 0.00  size:408454
> [libx264 @ 0xae55820] frame P:343   Avg QP: 0.00  size:122254
> [libx264 @ 0xae55820] mb I  I16..4: 100.0%  0.0%  0.0%
> [libx264 @ 0xae55820] mb P  I16..4: 15.1%  0.0%  0.0%  P16..4: 20.6%
> 0.0%  0.0%  0.0%  0.0%    skip:64.2%
> [libx264 @ 0xae55820] coded y,uvDC,uvAC intra: 91.4% 90.8% 90.7%
> inter: 17.5% 23.5% 23.3%
> [libx264 @ 0xae55820] i16 v,h,dc,p: 40% 59%  0%  0%
> [libx264 @ 0xae55820] i8c dc,h,v,p: 11% 57% 31%  0%
> [libx264 @ 0xae55820] kb/s:4956.54
>
>
> Here also is the result of the FFplay command;
>
> $ ffplay output.mkv
> ffplay version N-42139-g7693543 Copyright (c) 2003-2012 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
> Input #0, matroska,webm, from 'output.mkv':
>   Metadata:
>     ENCODER         : Lavf54.36.100
>   Duration: 00:01:09.82, start: 0.000000, bitrate: 6477 kb/s
>     Stream #0:0: Video: h264 (High 4:4:4 Predictive), yuv420p,
> 1280x800, SAR 1:1 DAR 8:5, 5 fps, 5 tbr, 1k tbn, 10 tbc (default)
>     Stream #0:1: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536
> kb/s (default)
> Frame changed from size:0x0 to size:1280x800632KB sq=    0B f=0/0
>   23.42 A-V: -0.185 fd=   1 aq=  429KB vq=  845KB sq=    0B f=0/0
>
>
>
>
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