Newest 'ffmpeg' Questions - Stack Overflow

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• How to convert an mkv (with subtitles) to something Nexus One friendly ?

  21 décembre 2011, par Daniel Quinn

  I have this ffmpeg one-liner that's been good for generating video files for my Nexus One:

  ffmpeg -i infile.mkv -acodec aac -s 572x238 -vcodec libx264 -vpre ipod640 -ab 128k -b 512k -f mp4 -strict experimental outfile.mp4
  

  But it does this ignorant of the subtitles in infile.mkv -- usually not a problem, unless I'm dealing with a non-english movie. In cases like this, I'd like to use the Japanese audio track, and the English subtitles.

  The funny bit is that I can use mplayer to play it using -alang and -slang, but don't know how to use mencoder to make Nexus One friendly videos. I can use ffmpeg to generate Nexus One friendly videos, but can't figure out how to get it to use a specific subtitle track.

  If someone can solve one of these for me, I'll be a happy camper.

• Legal Issues with FFMPEG ? [closed]

  21 décembre 2011, par Jimmery

  Has anybody had any legal issues using FFMPEG in a commerical product, particularly from MPEG LA?

  I only ask from reading the bottom of this page: http://ffmpeg.org/legal.html

  We are hoping to produce a website that uses FFMPEG (or similar program), currently the website will be free to use. However we do hope of monetizing aspects of the website later down the line, and wouldnt want to hit any legal issues at that point.

  If this is an issue, does anybody know of a good alternative to FFMPEG which does not have these legal issues?

• Selecting a library / framework for video capture & recording

  21 décembre 2011, par Saurabh Gandhi

  In one of the project that we have undertaken we are looking for a video capture & recording library. Our groundwork (based on google search) shows that vlc (libvlc), ffmpeg (libavcodec) and gstreamer are the three popular free and open source libraries / multimedia frameworks available for the same. How do these libraries compare on the following parameters:

  1. Licensing policy to allow use within a commercial product without the need to open source any of the components of the product that is using the library
  2. Ability to be used effectively in a multi-threaded environment (library should be inherently thread-safe)
  3. Easy to use and maintain
  4. Documentation: API should be well documented...this is relative...:)

  Our primary intention is to be able to capture RTSP video streams (H.264/MPEG-2/MJPEG encoded), convert these streams to raw video / frames so that it can be used for analysis / processing and later on compress these frames and store it on the disk in the form of an MP4 file (using MPEG2 / H.264 encoding).

  P.S. We understand that FFmpeg is also one of the components of vlc since vlc uses libavcodec library. Is the same true for gstreamer as well? Does it have any ffmpeg dependency?

  Awaiting your responses.

  Regards,

  Saurabh Gandhi

• FFMPEG reports invalid video resolution, video headers container seem to be different from actual frames !

  20 décembre 2011, par Emiliano

  Quick question, i have a movie, which was cut and rendered with Sony Vegas from its original format to a .wmv file. Here comes the tricky part, movie when played, either with VLC or WMP, has a resolution of 656x480 ... BUT when i run a ffmpeg -i on it, it says it has a resolution of 600x480 ....

  I took the time of actually capturing a frame and croping it with photoshop and its 656 and not 600 like ffmpeg its reporting, why would this could be happening? How could i fix the headers resolution? Would that have any impact on video re-rendering? As i said, VLC and WMP seems not to care about the incorrect headers and are playing it right, BUT, jwplayer seems to be using the header information, which i don't blame him, its correct to do that, but why the video headers could be wrong?

  ffmpeg -i trailer.wmv
  

  Input #0, asf, from 'trailer.wmv':
  Duration: 00:01:04.93, start: 3.000000, bitrate: 2144 kb/s
  Stream #0.0: Audio: wmav2, 44100 Hz, mono, 32 kb/s
  Stream #0.1: Video: wmv3, yuv420p, 600x480 [PAR 59:54 DAR 295:216], 2065 kb/
  s, 25.00 tb(r)

  And yeah, the PAR/DAR parameters are also wrong, but honestly, i don't understand that technical shit, usually watch video and make sure it look good, any feedback would be appreciated :P

  Is there a way to change the container information with ffmpeg so applications that actually do use the container information don't render video incorrectly?

• Batch statement to convert mp3 to aac

  20 décembre 2011, par Soham Dasgupta

  My question is straight forward. I have tow commands to convert a single mp3 file to aac in tow pass. Here are the commands -

  ffmpeg -i input.mp3 -f wav - | neroAacEnc -ignorelength -q 0.5 -if - -of output.m4a
  
  ffmpeg -i output.m4a -y -vn -acodec libvo_aacenc -ab 128k -ar 48000 -ac 2 final.aac
  

  Please guide me to some script where I'll be able to convert a folder full to mp3 files in one shot. Suppose if its a VBScript then would it ask for the folders where mp3 are kept.

  Also a question about libvo_aacenc codec, is it the best codec to convert to aac if not then what codec should I use for the second pass for converting m4a to aac with highest compression but good quality. The above settings does not produce too good compression. Please help. Am very new to audio encoding.