[Ffmpeg-devel] [PATCH] flacenc - rice param search
Wed Jun 28 04:38:21 CEST 2006
Michael Niedermayer wrote:
> On Tue, Jun 27, 2006 at 02:27:06AM -0400, Justin Ruggles wrote:
>>Here is another update for the FLAC encoder. I only added a few things,
>>but it's still a pretty large patch.
>>1) search for optimal rice parameters and partition order. i also
>>modified the stereo method estimation to use this to calculate estimated
>>bit count instead of using just the pure sums.
>>2) search for the best fixed prediction order
>>3) constant subframe mode (good for encoding silence)
>>Note that the regression test for the decoded wav file also changed.
>>This is due to FFmpeg's FLAC decoder truncating the file, which it did
>>before anyway...just at a different cutoff point. The generated FLAC
>>files are still 100% lossless.
>>With this update, FFmpeg's FLAC encoder has speed and compression
>>somewhere between "flac -1" and "flac -2". On my machine, it's about
>>15% faster than "flac -2", and about 10% slower than "flac -1". The
>>encoding parameters are identical to "flac -2" (fixed predictors, 1152
>>blocksize, partition order 0 to 3).
Great! Thanks. :)
Now I have a question. I want to eventually add capability for the user
to specify the compression level. Would it be okay to use "-aq", which
uses avctx->global_quality, for this purpose? I know it isn't really
"audio quality" since it's lossless, but it is compression quality, and
this seems like the simplest solution to me.
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