[FFmpeg-user] Replace part of the audio

Michael Koch astroelectronic at t-online.de
Sun Jan 22 20:48:08 EET 2023

Am 22.01.2023 um 19:21 schrieb Paul B Mahol:
> On 1/22/23, Michael Koch <astroelectronic at t-online.de> wrote:
>> Am 22.01.2023 um 16:56 schrieb Michael Koch:
>>> Am 22.01.2023 um 16:25 schrieb Paul B Mahol:
>>>> On 1/22/23, Michael Koch <astroelectronic at t-online.de> wrote:
>>>>> Am 21.01.2023 um 17:05 schrieb Paul B Mahol:
>>>>>> On 1/19/23, Michael Koch <astroelectronic at t-online.de> wrote:
>>>>>>> Am 19.01.2023 um 15:49 schrieb Alexander Bieliaev via ffmpeg-user:
>>>>>>>> How can I replace a part of the audio from and to a specific time
>>>>>>>> with
>>>>>>>> some
>>>>>>>> other audio/sound (I want to replace it with beep in this case)?
>>>>>>> Here is an example:
>>>>>>> ffmpeg -lavfi sine=500:d=10 -y audio1.wav
>>>>>>> ffmpeg -lavfi sine=2000:d=10 -y audio2.wav
>>>>>>> ffmpeg -i audio1.wav -i audio2.wav -lavfi
>>>>>>> [0]volume='1-between(t,4,6)':eval=frame[a];[1]volume='between(t,4,6)':eval=frame[b];[a][b]amix
>>>>>>> -y out.wav
>>>>>> That is never going to give smooth transitions.
>>>>>> Also overly complicated as can be simplified with commands to to amix
>>>>>> filter.
>>>>> If my example is too complicated, then please show a simpler example.
>>>> asendcmd=10.0 amix weights 'X Y',
>>>> X/Y being wanted volume of first/second input to amix filter.
>>> That doesn't work because the argument of asendcmd must be
>>> encapsulated in quotes (because it contains spaces), and X Y must also
>>> be encapsulated in quotes. Please show the whole command line.
>> This command line works with asendcmd and astreamselect:
>> ffmpeg -i audio1.wav -i audio2.wav -lavfi asendcmd="4 astreamselect map
>> 1",asendcmd="6 astreamselect map 0",astreamselect=map=0 -y out.wav
>> However with amix filter I have no idea what's the syntax for the string
>> inside the string. It doesn't work.
>> ffmpeg -i audio1.wav -i audio2.wav -lavfi asendcmd="4 amix weights '0
>> 1'",amix=weights='1 0' -y out.wav
> there is way to escape stuff

Above you wrote that the command line can be simplified, and now 
escaping is required? That's too complicated. I'm out.


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