[FFmpeg-devel] [PATCH] LGPL AC3 decoding
Tue May 19 23:29:35 CEST 2009
On Tue, May 19, 2009 at 3:26 AM, Diego Biurrun <diego at biurrun.de> wrote:
> On Mon, May 18, 2009 at 08:38:56PM -0400, Justin Ruggles wrote:
>> Jason Garrett-Glaser wrote:
>> > This patch contains a clean-room-written
>> > ac3_decode_transform_coeffs_ch, written solely from the spec and
>> > Justin's copious advice and descriptions (no knowledge of the original
>> > function). ?Oddly enough, it seems to actually be closer to the
>> > original liba52 code, despite the fact that I never saw that either.
>> > According to Diego, this should be sufficient to finally LGPL ffac3;
>> > I'll let someone else handle the header/configure changes for that.
>> > Bonus: mine's faster, too. ?With GCC 3.4 on 32-bit Core 2 Conroe
>> > (First 1234901 bytes of Broadway-5.1-48khz-448kbit.ac3):
>> > Before: 27908.6 dezicycles (+/- 9.7)
>> > After: 24820.6 dezicycles (+/- 12.4)
>> > Total: 12.4% faster ac3_decode_transform_coeffs_ch
>> > PSNR-wise it matches the original exactly; this was achieved through
>> > Justin supplying me with the single line of code for the bap=0 noise
>> > from the original code. ?Note that I have not tested this on anything
>> > other than that sample of Broadway, so I cannot guarantee it works for
>> > all files.
>> It looks good to me. ?I tested it out on a few other files and also got
>> identical results.
> Excellent! ?Somebody commit this, I'll handle the rest.
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