Fixes issue on iPad Pro 10.5 (and probably other places) where threads
are not properly synchronized. On x86 this data race was benign as load
and store instructions are atomic, they were being atomic in practice as
the program hasn't been observed to be miscompiled.
Such guarantees are not made outside x86, and real problems manifested
where libvpx reliably reproduced a broken bitstream for even just the
initial keyframe. This was detected in WebRTC where this device started
using multithreading (as its CPU count is higher than earlier devices,
where the problem did not manifest as single-threading was used in
practice).
This issue was not detected under thread-sanitizer bots as mutexes were
conditionally used under this platform to simulate the protected read
and write semantics that were in practice provided on x86 platforms.
This change also removes several mutexes, so encoder/decoder state is
lighter-weight after this change and we do not need to initialize so
many mutexes (this was done even on non-thread-sanitizer platforms where
they were unused).
Change-Id: If41fcb0d99944f7bbc8ec40877cdc34d672ae72a
Reapply this patch:
ff0107f Amend and improve VP8 multithreading implementation
Amended the patch to add a unit test, and fix an asan error.
BUG=webm:851
Change-Id: I6572c03256169c64e80248bf5a5e99f59a2fc93c
This patch was to fix a reported Hangouts deadlock/freezing issue
in VP8 encoder(issue 27232610). The original encoder loopfilter
synchronization happened in the following frame, which was prone
to causing problems in some complex use cases. This patch simplified
the synchronization logic.
More testing needs to be done.
Change-Id: I38fd3f35d11f98fae1e44546aa5e4c6d6e19c4be
There are flaws in current implementation of VP8 multithreading encoder
and decoder as reported in the following issue:
https://code.google.com/p/chromium/issues/detail?id=158922
Although the data race warnings are harmless, and wouldn't cause real
problems while encoding and decoding videos, it is better to fix the
warnings so that VP8 code could pass the TSan test.
To synchronize the thread-shared data access and maintain the speed
(i.e. decoding speed), use multiple mutexes based on mb_rows to reduce
the number of synchronizations needed, make the reads and writes of
the shared data protected, and reduce the number of mb_col writes by
nsync times.
The decoder speed tests showed < 3% speed loss while using 2 ~ 4
threads.
Change-Id: Ie296defffcd86a693188b668270d811964227882
The obj_int_extract code is no longer worth maintaining. It creates
significant issues when adapting for different build systems and no
longer offers as significant of a performance benefit due to
improvements in intrinsics.
Source files will remain until the various third-party builds are updated.
The neon fast quantizer has been moved to intrinsics. The armv6 version
has been removed because so few remaining targets require it.
Compilers and processors have improved significantly since the
pack_tokens code was written. The assembly is no longer faster than the
C code.
pack_tokens were the only optimizations for the armv5te targets so the targets
will be removed after the test infrastructure has been updated.
BUG=710
Change-Id: Ic785b167cd9f95eeff31c7c76b7b736c07fb30eb
Multi-threaded code was not updated to disable background
refresh for non base-layer frames at the time it was
disabled in the main C-code.
Change-Id: Id6cc376130b7def046942121cfd0526b4f0a71d4
The current way of counting inter_zz_count doesn't work correctly
in multi-threaded encoding. Calculating it after the frame is
encoded fixed the problem.
Change-Id: Ifcb1972cde950b8cc194f75c6d7b6af09e8b0e65
The sync interval for the multithreaded encoder was considered as not changing
during the encoding. This is not true if picture size is changed.
The encoder could dead-lock because the main thread and the other threads were
using different sync interval.
Change-Id: I75232bbdbc6c02d77f830d870fd8b4e96697c64e
Precalculated block ptrs do not need updates during encoding.
Set these at init stage.
Moved the allocation of 'mt_current_mb_col' (last encoded MB on each
row) to vp8_alloc_compressor_data(), so that it is correctly
reallocated when frame size is changing.
Change-Id: Idcdaa2d0cf3a7f782b7d888626b7cf22a4ffb5c1
Allows building the library with the gcc -pedantic option, for improved
portabilty. In particular, this commit removes usage of C99/C++ style
single-line comments and dynamic struct initializers. This is a
continuation of the work done in commit 97b766a46, which removed most
of these warnings for decode only builds.
Change-Id: Id453d9c1d9f44cc0381b10c3869fabb0184d5966
Change If4321cc5 fixed a bug caused by forward declarations not being
kept in sync across C files, resulting in a function call with the
wrong arguments. The commit moves the affected function declarations
into a header file, along with the other symbols from encodeframe.c
that were being sloppily shared.
Change-Id: I76a7b4c66d4fe175f9cbef7e52148655e4bb9ba1
RD costs were local to MACROBLOCK data and had to be copied all the
time to each thread's MACROBLOCK data. Tables moved to a common place
and only pointers are setup for each encoding thread.
vp8_cost_tokens() generates 'int' costs so changed all types to be
int (i.e. removed unsigned).
NOTE: Could do some more cleaning in vp8cx_init_mbrthread_data().
Change-Id: Ifa4de4c6286dffaca7ed3082041fe5af1345ddc0
Produce the token partitions on-the-fly, while processing each MB.
Context is updated at the beginning of each frame based on the
previoud frame's counters. Optimally encoder outputs partitions in
separate buffers. For frame based output, partitions are concatenated
internally.
Limitations:
- enabled just in combination with realtime-only mode
- number of encoding threads has to be equal or less than the
number of token partitions. For this reason, by default the encoder
will do 8 token partitions.
- vpxenc supports partition output (-P) just in combination with
IVF output format (--ivf)
Performance:
- Realtime encoder can be up to 13% faster (ARM) depending on the number
of threads and bitrate settings. Constant gain over the 5-16 speed
range.
- Token buffer reduced from one frame to 8 MBs
Quality:
- quality is affected by the delayed context updates. This again
dependents on input material, speed and bitrate settings. For VC
style input the loss seen is up to 0.2dB. If error-resilient=2
mode is used than the effect of this change is negligible.
Example:
./configure --enable-realtime-only --enable-onthefly-bitpacking
./vpxenc --rt --end-usage=1 --fps=30000/1000 -w 640 -h 480
--target-bitrate=1000 --token-parts=3 --static-thresh=2000
--ivf -P -t 4 -o strm.ivf tanya_640x480.yuv
Change-Id: I127295cb85b835fc287e1c0201a67e378d025d76
Second shot at this...
Sync with loopfilter thread as late as possible, usually just at the
beginning of next frame encoding. This returns control to application
faster and allows a better multicore scaling.
When PSNR packets are generated the final filtered frame is needed
imediatly so we cannot delay the sync. Same has to be done when
internal frame is previewed.
Change-Id: I64e110c8b224dd967faefffd9c93dd8dbad4a5b5
This commit continues the process of converting to the new RTCD
system. It removes the last of the VP8_ENCODER_RTCD struct references.
Change-Id: I2a44f52d7cccf5177e1ca98a028ead570d045395
