[FFmpeg-devel] [PATCH 0/4] fftw exploration (WIP)

[Hendrik Leppkes]

On Fri, Mar 25, 2016 at 3:34 PM, Ganesh Ajjanagadde <gajjanag at gmail.com> wrote:
> On Fri, Mar 25, 2016 at 12:35 AM, Clément Bœsch <u at pkh.me> wrote:
>> On Thu, Mar 24, 2016 at 05:50:48PM -0700, Ganesh Ajjanagadde wrote:
>>> Ganesh Ajjanagadde (4):
>>>   configure: add fftw3 detection
>>>   lavc/fftw: add initial fftw wrapper
>>>   lavc/fft-test: add FFTW3 tests
>>>   lavc/fft-test: update benchmark code
>>>
>>
>> Why?
>>
>> Using an external library for such an essential component sounds like
>> madness to me.
>
> I don't really understand. It is an opt-in dependency, and does not
> have to be used. Seems like I don't really understand the FFmpeg
> philosophy; there are a ton of optional libs in configure. FFT is not
> used in all codecs, so I view it on the same lines as having things
> like libopus based decoding instead of native FFmpeg decoding, the
> multiple AAC encoders/decoders, the duplicate prores stuff, libnut on
> top of the native demuxer, etc, etc.
>

The way I see it, external libraries should only be used if they
provide actual features (for example new formats not otherwise
supported, or access to hardware de/encoders), or a higher quality
(ie. for encoders).
Using external libraries for small performance gains seems rather
overkill, resulting in code rot and maintenance burden.

If performance is the only reason one might want an external library,
then its a much better idea to try to optimize the code we have, that
way more people automatically benefit from this, and we avoid this
complexity.

- Hendrik