Implemented parallel loopfiltering, which uses existing tile-
decoding threads. Each thread works on one row, and when that row
is loopfiltered, it moves to next unattended row. To ensure the
correct filtering order, threads are synchronized and one
superblock is filtered only if the superblocks it depends on are
filtered already.
To reduce synchronization overhead and speed up the decoder, we use
nsync > 1 for high resolution.
Performance tests:
1. on desktop:
8-tile 4k video using 8 threads, speedup: 70% - 80%
4-tile HD video using 4 threads, speedup: ~35%
2. on mobile device(Nexus 7):
4-tile 1080p video using 4 threads, speedup: 18% - 25%
4-tile 1080p video using 2 threads, speedup: 10% - 15%
Change-Id: If54b4a11960dd706c22d5ad145ad94156031f36a
cherry-picked from:
commit 988b70844e03efcfcc075a9bc25d846670494f36
Author: Pascal Massimino <pascal.massimino@gmail.com>
Date: Fri Aug 2 11:15:16 2013 -0700
add WebPWorkerExecute() for convenient bypass
This is mainly for re-using the worker structs without using the
thread.
Change-Id: I8e1be29e53874ef425b15c192fb68036b4c0a359
Original source:
http://git.chromium.org/webm/libwebp.git
100644 blob c0d318aee628fdf9ba4876451a28aa978f1066b8 src/utils/thread.c
100644 blob c2b92c9fe353f8e514f78922f3d237204a9cbc66 src/utils/thread.h
Change-Id: I13fe92b1e94062bb99fdeeb7cb0b4b0575d27793
