[MEncoder-users] Transcode from .MTS to wmv with MEncoder fails

Jan Ehrhardt phpdev at ehrhardt.nl
Fri Feb 15 17:24:59 CET 2013


Carl Eugen Hoyos in gmane.comp.video.mencoder.user (Fri, 15 Feb 2013
14:37:57 +0000 (UTC)):
>Jan Ehrhardt <phpdev <at> ehrhardt.nl> writes:
> 
>> I once again tried MEncoder to transcode a .MTS file from a Canon
>> camcorder to WMV-format. As a starter: I prefer MEncoder over FFmpeg
>> because of the volnorm filter.
>
>Could you open a ticket on trac?

I will do.

>Or give an example for the use-case (I never used the filter, 
>I don't know what it does).

It 'normalizes' the audio volume by looking back a few samples. See
http://www.mplayerhq.hu/DOCS/man/en/mplayer.1.html#AUDIO%20FILTERS
Quote: Use a single sample to smooth the variations via the standard
weighted mean over past samples (default).

We have lots of low volume videos (speech in various circumstances) that
need a higher volume without the user selecting it manually. The volnorm
filter does that perfectly.

>> Simple question: MEncoder uses FFmpeg for the trancoding. Why does it
>> fail when exactly the same FFmpeg as separate program transcodes it
>> fine?
>
>Because MEncoder is not a maintained application for 
>a long time / because you misunderstand how it works: 
>MEncoder does not use FFmpeg, it uses libavcodec and 
>libavformat, and it uses them differently.

I know MEncoder does not call FFmpeg as a whole, but its libraries. And
those libraries are perfectly able to transcode from .MTS to .wmv.

And with respect to the maintenance: it was maintenance that disabled
the perfect transcoding close nearby revision 34000. Bisecting is not
easy, because r33986 (for instance) only compiles with FFmpeg 0.8.git
(and for instance not with 0.8.1.git).

Later on (somewhere between Subjunk builds 38 and 45) the workaround by
using the telecine filter went broken as well.

Jan




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