[FFmpeg-devel] [PATCH] avfilter: add apitch filter

Paul B Mahol onemda at gmail.com
Sat May 18 13:44:28 EEST 2019


On 5/18/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Wed, May 15, 2019 at 07:19:43PM +0200, Paul B Mahol wrote:
>> On 5/12/19, Paul B Mahol <onemda at gmail.com> wrote:
>> > On 5/12/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
>> >> On Sun, May 12, 2019 at 11:00:51PM +0200, Nicolas George wrote:
>> >>> Marton Balint (12019-05-12):
>> >>> > Yeah, you are right, what I had in mind was this:
>> >>> >
>> >>> > apitch  ===  asetrate,aresample,atempo
>> >>>
>> >>> Exactly. And reciprocally, atempo = apitch+asetrate+aresample.
>> >>>
>> >>> Furthermore, since it works with the spectrum, the filter that does
>> >>> the
>> >>> hard work can probably easily output at any sample rate, at a cost
>> >>> much
>> >>> lower than resampling afterwards. Therefore, it makes most sense to
>> >>> have
>> >>> a single filter with all three parameters (sample rate, speed
>> >>> adjustment
>> >>> and pitch adjustment).
>> >>
>> >> and if thats done in our resampler than that can also be combined with
>> >> changing the channel order, layout, sample type and so on.
>> >> Iam not sure its a good idea but purely technically it should be more
>> >> efficient to do it all together.
>> >> Also swresample already supports an external FFT resampler so it might
>> >> actually fit in there nicely and it might even allow us to remove an
>> >> external
>> >> dependancy without loosing a feature. (assuming the new FFT resampler
>> >> would be equally good)
>> >>
>> >>
>> >
>> > To make it work dynamically, filter must resample audio internally.
>> >
>>
>> Can I get testers?
>
> Iam not sure what you ask for exactly (which is why i didnt reply sooner)
> but if theres a patch for an implementation in swr then sure as the
> maintainer
> of swr i will test it. But iam not sure thats what you had in mind ...
>

Why you want to put everything in swr?
Swr is not for time stretching and pitch shifting.
More over it can be done in several ways.


> Thanks
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> When you are offended at any man's fault, turn to yourself and study your
> own failings. Then you will forget your anger. -- Epictetus
>


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