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

[Zoltan Kerenyi Nagy]

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.


On Tue, 29 Jan 2019 at 22:19, Zoltan Kerenyi Nagy <
kerenyi.nagy.zoltan at gmail.com> wrote:

> Hi,
>
> I'd like to send the analog audio as video with waveform superimposed, I
> did this so far:
>
> ffmpeg -f alsa -i hw:0,0 -f lavfi -i nullsrc -filter_complex
> "[0:a]showwaves=mode=line:s=hd480:colors=Red[v]" -map "[v]" -map 0:a
> -pix_fmt yuv420p -b:a 360k -r:a 44100 http://localhost:5554/video.ffm
>
> /etc/ffserver.conf
>
> HTTPPort 5554
> HTTPBindAddress 0.0.0.0
> MaxHTTPConnections 10
> MaxClients 10
> MaxBandwidth 1024
> CustomLog -
>
> <Feed video.ffm>
>     File /tmp/video.ffm
>     FileMaxSize 2048M
> </Feed>
>
> #####################
>
> <Stream video>
>     Format flv
>     Feed video.ffm
>     VideoCodec libx264
>     VideoFrameRate 15
>     VideoBitRate 512
>     VideoSize 1280x720
>     AVOptionVideo crf 23
>     AVOptionVideo preset medium
>     AVOptionVideo flags +global_header
>
>     AudioCodec aac
>     Strict -2
>     AudioBitRate 128
>     AudioChannels 2
>     AudioSampleRate 44100
>     AVOptionAudio flags +global_header
> </Stream>
>
> The error message is:
>
> Filter showwaves has an unconnected output
> Tue Jan 29 22:18:08 2019 127.0.0.1 - - [POST] "/video.ffm HTTP/1.1" 200 0
>
>
> ------------------
> (program exited with code: 1)
> Press return to continue
>
>