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Yesterday I installed the latest Kubuntu release 14.04. So I meet a little problems with the media conversions. The old FFmpeg is finally replaced with avconv which is in the libav-tools library. Till now i was using ffmpeg and every mp4 or flv to mp3 conversion was very fast. For example if one file around 5mins length was converted for ~20secs, now the same file is converted ~3-4-5 times slower. I read everywhere, but could not find where is the problem.. Is there any cure about that?

Best regards :)

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  • Short of askubuntu.com/questions/373322/… ... you can check if the static ffmpeg is still faster to rule out some other problem. – Rmano Apr 18 '14 at 18:22
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    Yes. I already been downloaded the static ffmpeg version because my other question here, it works faster and after all i'm using it for now. But my question is about avconv.. I doubt it's something normal to be so slower than ffmpeg. – m1nev Apr 18 '14 at 19:41
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So the answer is in one simple parameter -vn which disable video recording for the output which is actually unneeded when making conversion from mp4(probably every video file) to mp3.

‘-vn (output)’ Disable video recording.

In my case I'm using Download Helper for Firefox. I made custom mp3 conversion where added this parameter there and now everything is even faster than ffmpeg.

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  • The -vn option has to be provided after the input is specified. Otherwise it doesn't seem to have an effect. – HRJ Aug 10 '14 at 16:30
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It would be well worth experimenting a little with the avconv -threads option. For example when transcoding from mp4 to mp3 file, as you mentioned, try something like the following:

avconv -i input.mp4 -threads auto -vn -c:a libmp3lame -qscale:a 3 output.mp3

The -threads option also accepts an integer so you could experiment a little with this. If this makes no difference the eventual answer is probably that your copy of FFmpeg encodes faster than your copy of avconv. Try using the time utility to quantify the difference...

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  • Yes, this line makes a difference. For example same file converted with ffmpeg done for 0m17.189s and avconv for 0m5.816s.. But the option which makes the difference wasn't -threads but the -vn. I take a look into avconv documentation and found -vn is kinda disabling video recording for the output. ‘-vn (output)’ Disable video recording. – m1nev May 29 '14 at 9:33
  • Yes, I thought you were talking about conversion to mp3? – andrew.46 May 29 '14 at 11:41
  • Yes.. Generally I'm converting media files from mp4 to mp3 using download helper in Firefox. Sometimes using Winff or such a software. – m1nev May 31 '14 at 17:54
  • So now I was testing conversion with avconv through "Download helper" and everything is blazing fast now without loss of quality. I just made custom mp3 conversation where I added "-vn" parameter in the parameters section. I'm cool now :) Thank you! – m1nev May 31 '14 at 18:15
  • Great news! So if you could find the 'best answer' button-thingy this question + thread will be complete :) – andrew.46 May 31 '14 at 22:43

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