[FFmpeg-devel] [PATCH] adpcm: Reset the ssd back to zero more often

[Martin Storsjö]

On Thu, 18 Nov 2010, Martin Storsjo wrote:

> If using very large trellis sizes (e.g. -trellis 15), the frontier
> is so large that the difference between the best and the worst
> trellis node in the frontier is large enough to cause wraparound.
> 
> Resetting at (1<<20) is enough to avoid the issue at -trellis 16
> with the sample I'm testing, therefore doing the resets at (1<<18)
> to have some extra safety margin.
> 
> This doesn't incur any noticeable slowdown.

This one is even more relevant now that the hash optimization has been 
committed, making it fast enough to actually use the really large trellis 
sizes, which currently can give really broken results due to wraparound.

// Martin