[FFmpeg-devel] [PATCH] FFV1 improvments

[Jason Garrett-Glaser]

On Sun, Oct 24, 2010 at 12:28 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Mon, Oct 11, 2010 at 01:25:35PM +0200, Michael Niedermayer wrote:
>> On Mon, Oct 11, 2010 at 09:59:16AM +0000, Loren Merritt wrote:
>> > On Sun, 10 Oct 2010, Jason Garrett-Glaser wrote:
>> >
>> >> On Sun, Oct 10, 2010 at 2:05 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >>> On Sun, Oct 10, 2010 at 01:19:57PM -0700, Jason Garrett-Glaser wrote:
>> >>>> On Sun, Oct 10, 2010 at 12:25 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >>>>> Hi
>> >>>>>
>> >>>>> Will apply patch-set below soon.
>> >>>>> bikesheds will be politely ignored
>> >>>>
>> >>>> Looks good;
>> >>>
>> >>> commited
>> >>>
>> >>>
>> >>>> what are the plans for version 2?
>> >>>
>> >>> the immedeate plan for ffv1.2 is to add rectangular slice based multithreading
>> >>> this should make the code much faster without extra delay
>> >>
>> >> Another thing you might want to try (since you're changing things...)
>> >> is Loren's median5 predictor; testing in FFV2 showed that it beat the
>> >> standard median predictor by a few % in terms of order-0 entropy. ?I
>> >> don't have it, but I assume he can post it here.
>> >
>> > median5(l, tr, l+t-tl, l*2-ll, t*2-tt)
>> > also, median3(l, tr, l+t-tl) is better than median3(l, t, l+t-tl)
>>
>> Thanks, ill look into trying/adding them to ffv1
>
> Tried on foreman:
> 18726558 pred_lor_median3.avi
> 18655092 pred_old_median.avi
> 18649580 pred_lor_median5.avi
> 18609236 pred_T_median5.avi
>
> Patches for the test attached
> Iam somewhat uncertain if the added complexity is worth the 0.25% gain
> maybe we can find a better predictor where the gain is bigger

How about LPC-based prediction?

Also, here's an interesting idea for you -- do the prediction in
higher precision, then weight probabilities accordingly.  Example:
Suppose you have a complex prediction function that returns "15.7".
Well, you can't compress a residual of "0.3", but you *do* know that
16 is far more likely than 15.  So there must be a way to "normalize"
the probability distribution to take this into account.

This will likely make fancier prediction functions much more useful.

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