[FFmpeg-user] Multiply audio samples

[Paul B Mahol]

On 9/20/18, Michael Koch <astroelectronic at t-online.de> wrote:
>
>>
>>> c://ffmpeg/ffmpeg -i ultrasonic.wav -f lavfi -i
>>> "sine=frequency=15000:sample_rate=48000" -filter_complex
>>> "[0]highpass=f=15000,highpass=f=15000,highpass=f=15000,highpass=f=15000[sound];[1]volume=8[sine];[sound][sine]amultiply[mixed];[mixed]lowpass=f=10000,lowpass=f=10000,lowpass=f=10000,lowpass=f=10000"
>>> out.wav
>
> The ultrasonics converter works fine if used with an audio file, but now
> I wanted to convert a video and I always get this error message
> "Unsupported channel layout "0 channels" which I don't understand. I
> want the audio be converted and the video copied as-is. Here is the
> console output:

add:

aformat=channel_layouts=stereo after aeval filter.