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I am trying to render a video spectrum of music using showwaves ... I need it to render with a transparent background (i think this is called an alpha channel?)...

I tried yuva420p but it's still rendering a black background... here's what I'm doing:

ffmpeg -i music.mp3 -filter_complex \
"[0:a]showwaves=s=1920x1080:mode=line:colors=white:draw=full,format=yuva420p[v]" \
-map "[v]" -map 0:a output.mp4;

Can anyone help? I know I'm close...

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2 Answers 2

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The default codec for MP4 is x264 which does not support alpha channel. Use PNG.

ffmpeg -i music.mp3 -filter_complex \
"[0:a]showwaves=s=1920x1080:mode=line:colors=white:draw=full,format=rgbap[v]" \
-map "[v]" -map 0:a -c:v png output.mp4;
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  • i actually found another method with qtrle and colorchannelmixer that works too ... still learning ffmpeg and not sure there's a significant difference since it gives me the output i want (although the files MOV files created by qtrle are HUGE!)
    – A K
    Jun 16, 2019 at 5:11
  • @AK, thank you here = voting up (click on the upper triangle) and / or accepting the answer (click on the check mark).
    – MarianD
    Jun 16, 2019 at 6:36
  • done so :) ... just learning the ropes
    – A K
    Jun 16, 2019 at 16:19
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Answering my own question after hours of research... this also works to give me a transparent background:

qtrle and colorchannelmixer got me there on my own:

ffmpeg -i music.mp3 -filter_complex \
"[0:a]showwaves=s=1920x1080:mode=line:colors=white:draw=full,colorchannelmixer=1:0:0:0:0:1:0:0:0:0:1:0:0.3:0.3:0.3:0" \
-map 0:a -c:v qtrle -an outputWaves.mov;```
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  • The ccc filter is not necessary. Add format=rgba instead.
    – Gyan
    Jun 16, 2019 at 6:45
  • while this is absolutely correct, i'm bringing the files into screenflow which apparently can't import the rgba format. I had to use qrtle to get them to import properly.
    – A K
    Jun 20, 2019 at 15:24

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