splitting video/audio and recombining - Linux-audio-user

Brett McCoy

4 Mar 4 Mar

8 p.m.

On Sun, Mar 4, 2012 at 1:48 PM, James Stone <jamesmstone(a)gmail.com> wrote:

Hi List, I have a video which needs a bit of eq'ing on the audio side. Can anyone point me in the direction of how to split the file into audio and video so I can apply some treatment to the audio, and then combine them back together again? The video is wmv at the moment, but mplayer doesn't seem to have any problem with it.

mplayer can do this: http://savvyadmin.com/extract-audio-from-video-files-to-wav-using-mplayer/ kdenlive also splits the audio and video if you want an NLE to do this with -- Brett W. McCoy -- http://www.brettwmccoy.com ------------------------------------------------------------------------ "In the rhythm of music a secret is hidden; If I were to divulge it, it would overturn the world." -- Jelaleddin Rumi

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Robin Gareus

8:12 p.m.

On 03/04/2012 07:48 PM, James Stone wrote:

...

Hi List, I have a video which needs a bit of eq'ing on the audio side. Can anyone point me in the direction of how to split the file into audio and video so I can apply some treatment to the audio, and then combine them back together again? The video is wmv at the moment, but mplayer doesn't seem to have any problem with it.

#extract audio ffmpeg -i orig_video.wmv audio_out.wav #replace audio ffmpeg \ -i orig_video.wmv \ -i new_audio.wav \ -vcodec copy \ -map 0.0 -map 1.0 \ new_video.wmv Details: The "map" may be different depending on the .wmv file. run `ffprobe` to see which is the video-track in the .wmv file usually this is "0.0". Stream #0.0: Video:... Stream #0.1: Audio: .. and "1.0" corresponds to the 2nd input file - your new audio. You may want to add "-acodec wmav2" and "-ar 128k" options for 128kbit/s Windows Media Audio 2 or whatever audio-codec/quality your want. `ffmpeg -codecs | grep "EA"` gives you a list of available codecs for Encoding Audio. BTW. Ardour3 with videotimeline patch can do all this for you. import,extract,re-encode using ffmpeg. robin

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Robin Gareus

9:44 a.m.

On 03/05/2012 08:18 AM, James Stone wrote:

...

On Mar 4, 2012 7:12 PM, "Robin Gareus" <robin(a)gareus.org> wrote:

On 03/04/2012 07:48 PM, James Stone wrote:

Hi List, I have a video which needs a bit of eq'ing on the audio side. Can anyone point me in the direction of how to split the file into audio and video so I can apply some treatment to the audio, and then combine them back together again? The video is wmv at the moment, but mplayer doesn't seem to have any problem with it.

#extract audio ffmpeg -i orig_video.wmv audio_out.wav #replace audio ffmpeg \ -i orig_video.wmv \ -i new_audio.wav \ -vcodec copy \ -map 0.0 -map 1.0 \ new_video.wmv Details: The "map" may be different depending on the .wmv file. run `ffprobe` to see which is the video-track in the .wmv file usually this is "0.0". Stream #0.0: Video:... Stream #0.1: Audio: .. and "1.0" corresponds to the 2nd input file - your new audio. You may want to add "-acodec wmav2" and "-ar 128k" options for 128kbit/s Windows Media Audio 2 or whatever audio-codec/quality your want. `ffmpeg -codecs | grep "EA"` gives you a list of available codecs for Encoding Audio.

Thanks. It is 0:0 and 0:1 and -b:a=192k I found, but I have some sync problems after recombining tho. Any other ideas?

My gut feeling is to blame ffmpeg's WMV muxer (it may not be able to mux a bit-exact copy of the original video with your new soundtrack). Try using '-sameq' instead of '-vcodec copy' (re-encode the video with same quality rather than a bit-exact copy - this often solves muxing issues but will cause a small loss of either video quality or increased bandwidth). and also try a different output format eg. 'new_video.avi' or '..mov' instead of 'new_video.wmv'. you may need both, this should work: 'ffmpeg -i vid.wmv -i aud.wav -sameq -map 0.0 -map 1.0 output.avi' welcome to the world of video. robin PS. yes, there are other options (lots of options for ffmpeg to configure the muxer) and other tools. e.g. 'mencoder' provides its own muxer-implementations for some formats.

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