[FFmpeg-user] ffmpeg audio encoding

[Edward Park]

Hi,

> i have a question what is the recommended way for transcoding only audio
> and keep video as is.
> 
> I tried this with command:
> ffmpeg -n -i something.mkv something_else.mkv -map 0 -vcodec copy -scodec
> copy -acodec ac3 -b:a 640k
> 
> The thing is that using this command with a 10+GB file the process is very
> very slow and it would take more than 1 day.
> 
> I tried manual to remove audio from mkv, encode it in ac3 and repack it
> back which was done in an h.
> 
> Do you have any idea what can be improved?


You need the output options before the output for them to have an effect. The command that takes 1 day is transcoding everything using default settings for mkv (including audio) and ignoring the trailing options.

Regards,
Ted Park