[FFmpeg-user] showvolume filter

[Nisar Ahmed]

Thanks, it works with input file but with decklink device the left bar is
showing value of inf and right bar is also showing a very small value which
clearly not the real values of both channels

Can you understand what is wrong here?

Thanks
On Apr 3, 2016 2:06 AM, "Moritz Barsnick" <barsnick at gmx.net> wrote:

> On Sun, Apr 03, 2016 at 01:14:47 +1100, Nisar Ahmed wrote:
> > I am using ffmpeg to capture audio/video from a decklink card and
> producing
> > 2 outputs from it, one is the captured movie file on disk and the other
> one
> > is mpegts stream for monitoring. The monitoring stream should have audio
> > bars for audio monitoring as well.
> >
> > ffmpeg -f decklink -i "DeckLink Intensity" -vcodec libx264 -acodec
> > libmp3lame -preset ultrafast -crf 30 output.mp4 -vf scale=640:-1 -f
> mpegts
> > udp://127.0.0.1:1234
> >
> > It would be best if I could overlay showvolumne filter or pipe it to
> ffplay
> > or both.
>
> For the monitoring output, use a comples filter as such:
>   [...] -filter_complex "[0:a]showvolume[vol]; [0:v][vol]overlay[v]" -map
> "[v]" -map 0:a <output>
>
> Perhaps adda box around the volume display, because it's not obvious it's
> there due to its transparency:
>   [...] -filter_complex "[0:a]showvolume,drawbox=w=iw:h=ih[vol];
> [0:v][vol]overlay[v]" -map "[v]" -map 0:a <output>
>
> You may want to also force the width of the bars to your output width
> (and I forgot to scale your monitoring stream):
>   [...] -filter_complex "[0:a]showvolume=w=640,drawbox=w=iw:h=ih[vol];
> [0:v]scale=640:-1[scaled]; [scaled][vol]overlay[v]" -map "[v]" -map 0:a
> <output>
>
> Moritz
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