[FFmpeg-devel] Interpolation algorithms for FFmpeg

Michael Niedermayer michaelni
Thu Jul 29 00:54:21 CEST 2010

On Wed, Jul 28, 2010 at 08:38:47PM +0200, Sebastian Vater wrote:
> Hi guys!
> In accordance with my chief I planned my Bachelor work to deal with interpolation algorithms and I also have to code one.
> After getting some informations from Benjamin Larsson what is already supported in FFmpeg, I was doing some research last weekend on interpolation for being a) usable for
> FFmpeg and b) for my Bachelor work.
> I found this one very interesting (Farrow Interpolation mode):
> http://www.mathworks.com/access/helpdesk/help/toolbox/dspblks/ref/variablefractionaldelay.html#f6-552788

what is farrow interpolation?
this text in that link is pretty much crap. I can explain what fir is in 2
lines they drag it out over pages and diagrams that only make sense to someone
who knows already what the things are besides that the informations is
obviously incomplete.

> I have to tell my chief next monday, which interpolation mode I want to implement in the Bachelor work (which could be included in FFmpeg, too).
> It will also be part of my GSoC project and be used by the mixing engine of libavsequencer, i.e. realtime appliance is required.
> Any ideas, comments?

ffmpeg would be interrested in any of the following
* picture scaling by doing interpolation along the direction of most equal
  color or otherwise along the texture pattern
* video frame rate changing by interpolation along motion vectors
* audio resampling by adaptively switching filters (for example filter
  length) depending on audio characteristics with the intent of maximizing
  similarity to the ideal/correct signal.

other ideas welcome but they must be formally well defined not links to
documents about commercial products.

and we alraedy have a FIR polyphase filter we dont need another under
different name.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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