[FFmpeg-devel] [PATCH] libavfilter/af_showvolume: A Simple Audio Filter for Extracting Volume Information

Clément Bœsch u at pkh.me
Wed Dec 24 09:22:07 CET 2014

On Wed, Dec 24, 2014 at 12:57:07AM +0100, Lars Kiesow wrote:
> Hi Stefano,
> my first idea was to have ffmpeg generate the image but you are right,
> that the unknown length is a problem. The only solution I could come up
> with was to have something like a two-pass encoding so that you know
> how many samples you have to deal with and in the second run generate
> the image.

I have a working local patch to add such thing in showwaves, which I'll
submit soon©®™

> But then I thought that is not worth the effort since it's really easy
> to just dump the data into something like gnuplot which is well tested
> and much more flexible than doing things on your own :)
> As I wrote already, I found another solution thanks to wm4 but maybe I
> will have a look at the signalstats filter anyway. In any case: Thanks
> for the hint.

You just want an ASCII output, don't you. I'm not sure if there are
already such defined format existing, but if it's not the case, there
aren't much to do. Probably something like:

# format=s16
# channel_layout=stereo
# sample_rate=44100
 64231  1234
  2312 -5433
-41223  6421

Last time I looked at this, I didn't find anything well defined or even
a convention in use.


Clément B.
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