[Cin] Any chance of adding FFMPeg's 'atempo' filter ?

[Andrew Randrianasulu]

On Saturday, June 19, 2021, Andrew Randrianasulu <randrianasulu at gmail.com>
wrote:

>
>
> On Saturday, June 19, 2021, Phyllis Smith via Cin <
> cin at lists.cinelerra-gg.org> wrote:
>
>> Gorge,
>> About crashing:
>>
>> That's odd, it's a tweaked version
>>>
>> Not the main.cpp program but the F_atempo plugin inside of Cinelerra.
>> Andrea is much more expert at testing the
>> ffmpeg plugins and it did not crash for him as stated in his email.  I
>> did get the plugin to not crash but I do not know
>> what it is doing.
>>
>
>
> random internet search says:
>
> The parameter for atempo must be between 0.5 and 2.0. If you want to slow
> it down even more, you can use the atempo filter more than once.
> Eg. to slow it down by 4:
> ffmpeg -i input.mp4 -filter:a "atempo=0.5,atempo=0.5" -vn output.aac
>
>
> https://muzso.hu/2015/04/25/how-to-speed-up-slow-down-an-
> audio-stream-with-ffmpeg
>
>
more random internet search unearth those finds:


https://patchwork.ffmpeg.org/project/ffmpeg/patch/20171202191342.25358-1-onemda@gmail.com/#21029

adds scaletempo filter, probably not in mainstream due to discussion about
how useful or not this new filter might be.

for rubberband apparently you need librubberband installed and pass
configuration flag to ffmpeg (cingg's build system allow this)
----
Apply time-stretching and pitch-shifting with librubberband.

To enable compilation of this filter, you need to configure FFmpeg with
--enable-librubberband.
----


>
>
>
>
>>
>>> When it runs , a terminal comes up to show you the technical info.  But
>>> the outfile is created.
>>>
>> I am still trying to compile the program because I have to put the
>> include <libavcodec/avcodec.h>  in the right place.
>> Then I will test it.  ...Phyllis
>>
>
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