[FFmpeg-devel] libswresample vs. libavresample

Michael Niedermayer michaelni at gmx.at
Thu Apr 26 03:56:41 CEST 2012

Hi ffmpeg devels, vlc devels
(vlc is in CC due to AFIAK interrest from vlc in these resampler libs)

last year libswresample was written with the goal to convert audio
from any channel layout, sample format and sample rate into any other.
And be the one, only and best at that, useable by all open source
projects. My hope was that libav too would include libswresample

This year ive been contacted by several directors of FFMTECH(1) about
a possible rewrite of libswresample and FFMTECH intending to fund
a friend of the FFMTECH directors to do this rewrite. When i heard
about that, i asked for the reasons behind a rewrite and offered to
implement any feature and any API FFMTECH or libav wants for free.
I hoped that a split of the resampler lib and API could be
avoided as its a huge annoyance for the whole community to deal with
2 incompatible libs ...
FFMTECH/libavs awnser was pretty much that they approved funding their
friend to do the rewrite.

Today libavresample got pushed to libav and while i had originally
not planed to merge it at all, considering the lack of any technical
need for it. I changed my mind and merged it for now, so ffmpeg 
continues to be a 100% drop in replacement for libav with many more
features and bugfixes. That way people also have the choice between
both libs in their applications. Though i would strongly suggest
users and developers use and develop libswresample
libswresample is and will be maintained by me and other ffmpeg
developers, while i wont fix
anything in libavresample. So i strongly suggest everyone uses
libswresample. I will also port every feature, optimiztaion, bugfix,
... to libswresample. That also means if you find something that
libavresample can do that libswresample cant, tell me ill fix it.
if you find a case where we are 0.5% slower, tell me, ill fix it.

(1) FFMTECH is the foundation that was founded to collect donations for
ffmpeg several years ago. After the fork FFMTECH due to a 1 head
majority of libav developers stoped supporting ffmpeg in any way and
since the fork has targetet 100% of their resources toward supporting
libav. Due to this they lost the right to collect donations in the name
of ffmpeg. The IRS has also rejected their tax exemption recently,
i do not know the details but it looks to me like their activities
where more in line with for profit corporations than non profit NGOs.
I would have really hoped that one of the current directors would
publish these things as they can say these things first hand and i
think the public and potential donors really should know these things
but well, noone else published it yet so better i do it than this
secrecy around FFMTECH continuing. Also FFMTECH has AFAIK used up
most of their accumulated donations now

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Good people do not need laws to tell them to act responsibly, while bad
people will find a way around the laws. -- Plato
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