[FFmpeg-user] "showwaves has an unconnected output" when sending audio with waveform as video

[Zoltan Kerenyi Nagy]

Neither does this work:

#OUTPUT=out.mp4
OUTPUT="http://localhost:5554/video.ffm"
ffmpeg -f alsa -i hw:0,0 -filter_complex
"[0:a]showwaves=split_channels=1:s=1280x720:mode=line:colors=Red|Blue[v]"
-map "[v]" -map 0:a $OUTPUT

On Wed, 30 Jan 2019 at 11:09, Zoltan Kerenyi Nagy <
kerenyi.nagy.zoltan at gmail.com> wrote:

> Thanks your're right!
>
> Unfortunately it still doesnt work:
> ffmpeg -f alsa -i hw:0,0 -f lavfi -i nullsrc -filter_complex
> "[0]showwaves=split_channels=1:s=1280x720:mode=line:colors=Red|Blue" -c:v
> libx264 -preset fast -crf 23 -c:a copy http://localhost:5554/video.ffm
>
> On Wed, 30 Jan 2019 at 09:45, Moritz Barsnick <barsnick at gmx.net> wrote:
>
>> On Tue, Jan 29, 2019 at 23:04:23 +0100, Zoltan Kerenyi Nagy wrote:
>> > Slight modification does not work either:
>> >
>> > ffmpeg -f lavfi -i nullsrc -f alsa -i hw:0,0 -filter_complex
>> > "[0:a]showwaves=s=1280x720:mode=line:colors=Blue[v]" -map "[v]" -map 0:a
>> > -c:v libx264 -r 15 http://localhost:5554/video.ffm
>> >
>> > error:
>> >
>> > Stream specifier ':a' in filtergraph description
>> > [0:a]showwaves=s=1280x720:mode=line:colors=Blue[v] matches no streams.
>>
>> This is why you should always show us the *complete* uncut console
>> output. You are hiding interesting info otherwise.
>>
>> Your first input (0) is nullsrc, a video source. So "[0:a]" does not
>> specify a valid stream. You are not even using nullsrc, so you should
>> probably omit "-f lavfi -i nullsrc", then the rest should work.
>>
>> Moritz
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>