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Old 08-20-2015, 06:22 AM   #1
Sefid par
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High quality desktop capture using FFMPEG


I want to capture my desktop using ffmepg. I'd like to understand it more.
I have 1366x768 desktop and used the following command to capture:
Code:
ffmpeg -video_size 1365x767 -framerate 25 -f x11grab -i :0.0 output.mp4
ffmpeg version: 2.6.3
But didn't produce high quality video.
How can I create better quality with it?

Also it has this output on terminal:

Code:
ffmpeg version 2.6.3 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.9.2 (GCC)
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --docdir=/usr/doc/ffmpeg-2.6.3/html --mandir=/usr/man --disable-debug --enable-shared --disable-static --enable-pthreads --enable-libtheora --enable-libvorbis --enable-gpl --enable-version3 --enable-postproc --enable-swscale --enable-x11grab --enable-avfilter --enable-gnutls --enable-libcdio --enable-libssh --enable-libcaca --enable-libsmbclient --enable-opengl --arch=x86_64
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, x11grab, from ':0.0':
  Duration: N/A, start: 1440065657.342327, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1365x767, 25 fps, 25 tbr, 1000k tbn, 25 tbc
File 'output2.mp4' already exists. Overwrite ? [y/N] y
Output #0, mp4, to 'output2.mp4':
  Metadata:
    encoder         : Lavf56.25.101
    Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 1365x767, q=2-31, 200 kb/s, 25 fps, 12800 tbn, 25 tbc
    Metadata:
      encoder         : Lavc56.26.100 mpeg4
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
[swscaler @ 0xb56500] Warning: data is not aligned! This can lead to a speedloss
Past duration 0.605492 too large     812kB time=00:00:03.92 bitrate=1697.8kbits/s dup=91 drop=0    
Past duration 0.678398 too large
Past duration 0.718544 too large
Past duration 0.614342 too large     868kB time=00:00:04.48 bitrate=1587.4kbits/s dup=91 drop=0    
Past duration 0.604546 too large     955kB time=00:00:05.00 bitrate=1564.8kbits/s dup=91 drop=0    
Past duration 0.624870 too large
Past duration 0.601967 too large    1025kB time=00:00:05.48 bitrate=1531.8kbits/s dup=91 drop=0    
Past duration 0.631111 too large    1074kB time=00:00:06.04 bitrate=1456.7kbits/s dup=91 drop=0    
Past duration 0.710487 too large
Past duration 0.631538 too large    1150kB time=00:00:06.56 bitrate=1436.6kbits/s dup=91 drop=0    
Past duration 0.682411 too large
Past duration 0.769875 too large
Past duration 0.609062 too large
frame=  412 fps= 30 q=24.8 Lsize=    2403kB time=00:00:16.48 bitrate=1194.3kbits/s dup=113 drop=0    
video:2400kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.109095
Received signal 2: terminating.

Last edited by Sefid par; 08-20-2015 at 06:27 AM.
 
Old 08-20-2015, 07:47 AM   #2
Keith Hedger
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you need to set the vscale option otherwise ffmpeg will use a variable video scale rate
 
Old 08-20-2015, 10:12 AM   #3
Sefid par
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Thank you. But id doesn't have vscale option. I've checked the man page.
Of course I found a solution, using video codec: h264:
Code:
fmpeg -video_size 1365x767 -framerate 25 -f x11grab -i :0.0 -vcodec h264 output14.mkv
In fact I needed to install the x264 first and then recompile ffmpeg using X264 library enabled.

Last edited by Sefid par; 08-22-2015 at 05:42 AM.
 
Old 08-20-2015, 10:37 AM   #4
Keith Hedger
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Sorry my bad missed the h264 qscale is used with mpg's like so
Code:
ffmpeg -video_size 1365x767 -framerate 25 -f x11grab -i :0.0  -q:v 0 output14.mpg
For best results.
Should have read your post properly
 
Old 08-20-2015, 05:23 PM   #5
Sefid par
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It seems it doesn't work on hw:0

Code:
Option q:v (use fixed quality scale (VBR)) cannot be applied to input file hw:0 -- you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to.
Error parsing options for input file hw:0.
 
Old 08-20-2015, 05:49 PM   #6
Sefid par
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It seems it doesn't work on hw:0

Code:
Option q:v (use fixed quality scale (VBR)) cannot be applied to input file hw:0 -- you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to.
Error parsing options for input file hw:0.
 
Old 08-20-2015, 06:17 PM   #7
Keith Hedger
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ffmpeg is very fussy about the order of the options, also the options change quite frequently, fyi i use the git version as it is always the most up to date
 
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Old 08-20-2015, 06:46 PM   #8
Shadow_7
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My avconv line of sorts (a fork of ffmpeg) uses -f alsa -i default which lets you bypass using hw:0 and lets your default in your .asoundrc handle that part. The only way so far that I've gotten recording to have "selectable" audio sources.

Code:
avconv -f alsa -i default -f  x11grab -s 1920x1080 -r:v 25 -draw_mouse 1 \
       -i :0.0+0,0 -r:v 25 -aspect 16:9 -pix_fmt yuv444p -async 1 \
       -codec:a pcm_s16le -filter_complex asyncts=compensate=1:min_delta=0.1:max_comp=500:first_pts=0" \
       -codec:v libx264 -pre:v lossless_ultrafast -y OUTPUT.mkv
The -async 1 and -filter_complex parts are to maintain video+audio sync. The -pix_fmt yuv444p is to maintain colors as yellows tend to not be yellow without it. Although my system is not that spec-tastic so my actual capture frame rate is closer to 5 for it to have a steady framerate and enough resources to have something worth recording.
 
  


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