Previously, the mode context is always udpated based on stats of current
frame, when there is no count, 50% is used for both left and right branch.
However, it is observed that with such strategy, a small count or no count
at all can skew the probability distribution significantly. This commmit
changed the mode_context update strategy to prevent small counts from
skewing the probability distributions.
Tests on derf set showed a small gain: .06% in psnr and .09% in ssim
Change-Id: Ic812e64ae5f70251c170b0717f7b7fa587055488
Previously, Y-adaptive UV intra coding only enabled on key frames in
UVINTRA experiment. This commit enabled the same coding for inter
frames, so the encoding of UV intra modes are consistent cross all
frame types. Tests on derf set showed a very small overall gain around
.04%:
http://www.corp.google.com/~yaowu/no_crawl/interUVintra.html
The gain looks to be reasonable given inta coded MBs is only a
small portion of MBs in inter frames.
Change-Id: Ic6fc261923f2c253f4a0c9f8bccf4797557b9e16
A previous commit 76feb965 made the vp8_mode_context adaptive on a frame
frame basis, this commit further made the coding context adaptive to two
frame types separately. Tests on derf set showed a further small gain on
all metrics: avg psnr 0.10%, glb psnr: 0.11%, ssim: 0.08%
http://www.corp.google.com/~yaowu/no_crawl/newNearMode_1209.html
Change-Id: I7b3e32ec8729de1903d14a3f1213f1624b78cdee
This commit removed the macro CONFIG_I8X8, which was used to indicate
the 8x8 intra prediction experiment, made the change fully merged in.
Change-Id: Iafa4443781ce6e83f5591c12ba615a0e92ce0ea0
vp8_mode_contexts[] is an entropy table used to code inter mode
choices. It was a fixed constant table. This commit made the entropy
context adaptive. Tests on derf set showed very good consistent gains
on all metrics: avg psnr .47%, overall psnr .46% and ssim .40%.
http://www.corp.google.com/~yaowu/no_crawl/newModeContext.html
Change-Id: Ia62b14485c948e2b74586118619c5eb2068b43b2
This commit enabled the usage of 8x8 intra prediction modes on inter
frames. There are a few TODO items related to this: 1)baseline entropy
need be calibrated; 2)cost of UV need to be done more properly rather
than using decision only relying on Y; 3)Threshold for allowing picking
8x8 intra prediction should be lowered to lower than the B_PRED.
Even with all the TODOs, tests showed consistent gain on derf set ~0.1%
(PSNR:0.08% and SSIM:0.14%). It is assumed that 8x8 intra prediction
will help more on large resolution clips, especially with above TODOs
addressed.
Change-Id: I398ada49dfc32575cfab962a569c2885111ae3ba
This commit tries to do UV intra mode coding adaptive to Y intra mode.
Entropy context is defined as conditional PDF of uv intra mode given
the Y mode. All constants are normalized with 256 to be fit in 8 bits.
This provides further coding efficiency beyond the quantizer adaptive
y intra mode coding. Consistent gains were observed on all clips and
all bit rates for HD all key encoding tests.
To test, configure with
--enable-experimental --enable-uvintra
Change-Id: I2d78d73f143127f063e19bd0bac3b68c418d756a
This commit added a 3 bit index to the bitstream, the index is used to
look into the intra mode coding entropy context table. The commit uses
the mode stats to calculate the cost of transmitting modes using 8
possible entropy distributions, and selects the distribution that
provides the lowest cost to do the actual mode coding.
Initial test show this provides additional .2%~.3% gain over quantizer
adaptive intra mode coding. So the adaptive intra mode coding provides
a total of .5%(psnr) to .6% gain(ssim) combined for all-key-encoding
To build and test, configure with
--enable-experimental --enable-qimode
Change-Id: I7c41cd8bfb352bc1fe7c5da1848a58faea5ed74a
make intra mode coding entropy distribution adaptive to baseQindex, an
encoding test on hd clips with all key frame shows universal gain on
all clips in both .2%(psnr) and (ssim).3%.
To build and test, configure with
--enable-experimental --enable-qimode
Change-Id: Iaa69241b984d4fdd8baa6d77ee78c0140f5ac00a
Patch 1 to Patch 3 is an initial implementation of 8x8 intra prediction
modes, here are with the following assumptions:
a. 8x8 has 4 prediction modes DC, H, V and TM
b. UV 4x4 block use the same mode as corresponding 8x8 area
c. i8x8 modes are enabled for key frame only for now
Patch 4:
d. removed debug code from previous patches
Patch 5:
e. added stats code to collect entropy stats and further cleaned up
Patch 6:
f. changed mode stats code to collect finer stats of modes
Patch 7:
g. normalized i8x8 modes distribution to total at 256 (8bits).
Patch 8:
h. fixed a bug in decoder and removed debug printf output.
Patch 9:
i. more cleanups to address paul's comment
Patch 10:
j. messy rebase/merges to bring the commit up to date.
Tests on HD clips encoded with all key frame showing consistent gain
on all clips and all metrics:~0.5%(psnr) and 0.6%(ssim):
http://www.corp.google.com/~yaowu/no_crawl/i8x8hd_allkey_fixedq.html
To build and test, configure with:
--enable-experimental --enable-i8x8
Change-Id: I9813fe07ae48cab5fdb5d904bca022514ad01e7f
Changes 'The VP8 project' to 'The WebM project', for consistency
with other webmproject.org repositories.
Fixes issue #97.
Change-Id: I37c13ed5fbdb9d334ceef71c6350e9febed9bbba
The mv_ref and sub_mv_ref token encodings are indexed from NEARESTMV
and LEFT4X4, respectively, rather than being zero-based like the
other token encodings.
Change-Id: I3699c3f84111209ecfb91097c4b900773e9a3ad5
When the license headers were updated, they accidentally contained
trailing whitespace, so unfortunately we have to touch all the files
again.
Change-Id: I236c05fade06589e417179c0444cb39b09e4200d
