[FFmpeg-user] Differences between ffmpeg and ffplay

Paul B Mahol onemda at gmail.com
Wed Oct 3 12:32:01 EEST 2018

On 10/3/18, Michael Koch <astroelectronic at t-online.de> wrote:
> Am 03.10.2018 um 10:43 schrieb Paul B Mahol:
>> On 10/2/18, Michael Koch <astroelectronic at t-online.de> wrote:
>>> I'm still experimenting with the ultrasonic converter. Converting from
>>> one file to another file works without problems:
>>> C:\Users\mkoch\Desktop\Ultrasonic Live>c://ffmpeg/ffmpeg -i
>>> test_15kHz.mp3 -f la
>>> vfi -i aevalsrc="sin(12000*2*PI*t):c=stereo:s=44100" -filter_complex
>>> "[0]volume=
>>> 1,highpass=f=12000,highpass=f=12000,highpass=f=12000,highpass=f=12000[sound];[so
>>> und][1]amultiply,lowpass=f=10000,lowpass=f=10000,lowpass=f=10000,lowpass=f=10000
>>> " -y out.mp3
>>> (no console output, because this is working fine)
>>> As the next step, I want to hear the output live on the speakers. I did
>>> use exactly the same command line as above, but I replaced ffmpeg by
>>> ffplay and I omitted the output file. At the end of the console output
>>> is an error message. Can't ffplay handle two inputs? Why doesn't ffplay
>>> accept the command line that works fine with ffmpeg?
>> You should really, really use mpv, it supports multiple inputs, and
>> complex filtergraph (unlike ffplay)
>> mpv test.mp3 -lavfi-complex
>> "aevalsrc=sin(5000*2*PI*t):c=stereo:s=44100[sine],[aid1]highpass=f=5000,highpass=f=5000,highpass=f=5000,highpass=f=5000[sound],[sound][sine]amultiply,dynaudnorm=m=100,lowpass=f=1000,lowpass=f=10000,lowpass=f=10000,lowpass=f=10000,asplit[ao],showspectrum=scale=log:size=hd720:color=channel[vo]"
> oh no, I don't want to learn a new command line syntax only to solve
> this simple problem.
> I have a long ffmpeg command line that's working fine when writing the
> output to a file. Is there really no easy way to send the output to the
> speakers instead?

It is very easy syntax to learn, you can send output directly to
speakers with ffmpeg
too but that is extremly limited funcionality.

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