[FFmpeg-devel] [PATCH 1/4] lavc/flacenc: add sse4 version of the 16-bit lpc encoder

James Darnley james.darnley at gmail.com
Mon Jul 21 00:32:23 CEST 2014

On 2014-03-15 00:01, Michael Niedermayer wrote:
> On Wed, Mar 12, 2014 at 01:03:03PM +0100, James Darnley wrote:
>> +; Is it worth looping correctly over the first samples?  The most that ever need
>> +; to be copied is 32 so we might as well just unroll the loop and do all 32.
> implementations should not make assumtations on their use except
> what is documented in the API
> or the other way around
> if some limitation is always true and you want to write an
> implementation that takes advantage of the limitation for optimization
> then this limitation should be documented in the API first
> (in this case of FLACDSPContext / lpc_encode)

So...  I've been bored lately and thought I'd come back to this.  I've
got a changed version which copies these samples in a loop.  You can see
the changes in these two links:

> https://gitorious.org/ffmpeg/jdarnley-ffmpeg/commit/9604911fbbe864cd0f670bdad47e7c5c2e83dc02
> https://gitorious.org/ffmpeg/jdarnley-ffmpeg/commit/837879d34100113105f099996ac67085d9c86396

These two are just about the same but apply to 16 and 32-bit.

Should I try to measure the difference between the two?  Or should I
just submit one version, possibly with suitable documentation?

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