Newest 'ffmpeg' Questions - Stack Overflow

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• How can I set up ALSA on VDS ?

  30 novembre 2014, par user2794729

  Greetings to everyone.

  I'm trying to convert SWF to MP4 using dump-gnash and ffmpeg.

  But the problem is the dump-gnash won't create raw video without ALSA set up properly.

  Here is a part of dump-gnash log:

  ALSA lib confmisc.c:768:(parse_card) cannot find card '0' ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default Killed

  I readed about ALSA and learned is't a sound card handler tool.

  But I don't have any sound cards on my VDS. Then there is a question: how can i set up ALSA on VDS and make it work?

• Call ffmpeg command from matlab (ubuntu 12.04)

  30 novembre 2014, par bigpig245

  I'm trying to call ffmpeg function to get duration of video from matlab. In command line, it returns ok:

  ntrang@ubuntu:~$ ffmpeg -i /home/ntrang/projects/dataset/hmdb51/01_test/a1.avi 2>&1 | sed -n "s/.*Duration: \([^,]*\), .*/\1/p"
  

  it returns 00:00:18.03

  But when I call it from matlab by system command:

  >> system('ffmpeg -i /home/ntrang/projects/dataset/hmdb51/01_test/a1.avi 2>&1 | sed -n "s/.*Duration: \([^,]*\), .*/\1/p"');
  

  it returns empty.

  This is my env setting in Matlab

  LD_LIBRARY_PATH='/usr/local/MATLAB/R2013a/sys/os/glnxa64:/usr/local/MATLAB/R2013a/bin/glnxa64:/usr/local/MATLAB/R2013a/extern/lib/glnxa64:/usr/local/MATLAB/R2013a/runtime/glnxa64:/usr/local/MATLAB/R2013a/sys/java/jre/glnxa64/jre/lib/amd64/native_threads:/usr/local/MATLAB/R2013a/sys/java/jre/glnxa64/jre/lib/amd64/server:/usr/local/MATLAB/R2013a/sys/java/jre/glnxa64/jre/lib/amd64'
  
  PATH='/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/lib/jvm/jdk1.7.0_51/bin'
  

  I also create symbolic link for libstdc but it can help nothing...

  I have looking around on Internet for solution but not so good so far... What should I do?

  I'm using Matlab R2013a on Ubuntu 12.04.5 LTS 64bit...

  Thanks in advance.

• FFmpeg build configuration for just AAC, MP3, WAV

  30 novembre 2014, par Krishna Mitta

  I need to use ffmpeg for just converting audio files between AAC, MP3, WAV only.

  So I want to compile ffmpeg for my requirement.

  But I don't know best ./configure bla bla bla... commandline for my requirement.

  Please help me. What is the best ./configure command line for me.

  Thanks in advance.

• ffmpeg concat best codec

  30 novembre 2014, par AnaetechEng

  I have been trying to get ffmpeg to format variously formatted files to 640x480 and 25fps, mp3 192k and concatenate the resulting file between a leader and trailer for projected display. My scripts appear to work with mp4 files of 25fps but not 24fps - this may be coincidence. ffmpeg concat gives the Non-monotonous DTS in output stream error.

  Apparently for concat to work the videos must be of the same format (the leader and trailer are produced with the same ffmpeg arguments). Can anyone show me how I can set the libx264 codec to produce compatible videos since size, fps and audio bps are not enough? Or suggest an alternative to libx264 or mp4 to increase the chance of successful concatenation.

  The three intermediate files all work fine but the concatenated video just silently skips through.

• ffmpeg/ffprobe : How to get the header size of AVI video file ?

  29 novembre 2014, par Peter Lur

  I can get several usefull informations about a video file using ffprobe and the following query:

  ffprobe -loglevel error -show_format -show_streams my-video.avi -print_format json
  

  However, I would like to find what is the header size (in bytes) of the actual AVI file, that infos is not provided in my above query?

  I found this information about AVI header size: http://www.fastgraph.com/help/avi_header_format.html but unfortunately it doesn't seem to be accurate since sometime the Header is bigger.