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

Michael Niedermayer michaelni at gmx.at
Mon Jul 21 01:48:52 CEST 2014

On Mon, Jul 21, 2014 at 12:32:23AM +0200, James Darnley wrote:
> 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?

fastest is best, and docs must match implementation but docs can be
changed for internal API



Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20140721/6afa6a5d/attachment.asc>

More information about the ffmpeg-devel mailing list