[Ffmpeg-devel] FLAC encoder
Sun May 28 20:16:18 CEST 2006
On Sun, May 28, 2006 at 10:54:06AM -0400, Justin Ruggles wrote:
> Michael Niedermayer wrote:
> > Hi
> > On Sun, May 28, 2006 at 12:32:36AM -0400, Justin Ruggles wrote:
> >>Here is an updated version of the encoder.
> >>What I did:
> >>Instead of doing brute-force bit counts and gradient search for the
> >>optimal rice parameters, I used the log2(mean_residual_value). This is
> >>not 100% optimal for compression, but it's close, and it is much faster.
> >> First, the mean is calculated for each partition on the highest order
> >>level. Then, each lower level mean is calculated by averaging each pair
> >>of partitions from the level above. In addition to calculating k, the
> >>means are also used to estimate bit count.
> > the same summing (of the most significant bits instead of all) from the
> > previous 2 higher order partitions can be done with the exact method too
> > (it was the simple but slower alternative i suggested)
> I think I see what you're suggesting now. I could more quickly
> calculate the sums for each k by doing partial sums for each of the 32
> bit positions then getting the bit count for each k by summing all
> partial sums for position k and above. Since my updated version
> estimates k, this wouldn't really help, but when I add the brute-force
> method back in, it will speed things up. I am understanding this right?
i think yes
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
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