Everything besides VLC.table is basically write-only
and even VLC.table can be removed by accessing the
underlying table directly.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Said object is only allowed to be modified during its
initialization and is immutable afterwards.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
For most VLCs here, the number of bits of the VLC is
write-only, because it is hardcoded at the call site.
Therefore one can replace these VLC structures with
the only thing that is actually used: The pointer
to the VLCElem table.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
These VLCs are very big: The VP3 one have 164382 elements
but due to the overallocation enough memory for 313344 elements
are allocated (1.195 MiB with sizeof(VLCElem) == 4);
for VP4 the numbers are very similar, namely 311296 and 164392
elements. Since 1f4cf92cfb, each
frame thread has its own copy of these VLCs.
This commit fixes this by sharing these VLCs across threads.
The approach used here will also make it easier to support
stream reconfigurations in case of frame-multithreading
in the future.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Also combine the ff_msmp4_dc_(luma|chroma)_vlcs as well
as the tables used to generate them to simplify the code.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Of all these VLCs here, only VLC.table was really used
after init, so use the ff_vlc_init_tables API
to get rid of them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
These are quite small and therefore force reloads
that can be avoided by modest increases in the number of bits used.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This is especially important for frame-threaded decoders like
this one, because up until now each thread had an identical
copy of all these VLC tables.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
For lots of static VLCs, the number of bits is not read from
VLC.bits, but rather a compile-constant that is hardcoded
at the callsite of get_vlc2(). Only VLC.table is ever used
and not using it directly is just an unnecessary indirection.
This commit adds helper functions and macros to avoid the VLC
structure when initializing VLC tables; there are 2x2 functions:
Two choices for init_sparse or from_lengths and two choices
for "overlong" initialization (as used when multiple VLCs are
initialized that share the same underlying table).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
The code above this does a whitelist on desc->flags, which now includes
the (disallowed) AV_PIX_FMT_FLAG_XYZ for XYZ formats. So there is no
more need for a separate check, here.
There are already several places in the codebase that match desc->name
against "xyz", and many downstream clients replicate this behavior.
I have no idea why this is not just a flag.
Motivated by my desire to add yet another check for XYZ to the codebase,
and I'd rather not keep copy/pasting a string comparison hack.
These are not supported by the drawing functions at all, and were
incorrectly advertised as supported in the past.
Note: This check is added only to separate the logic change from the API
change in the following commit, and will be removed again after it
becomes redundant.
Clang versions before 17 (Xcode versions up to and including 15.0)
had a very annoying bug in its behaviour of the ".arch" directive
in assembly. If the directive only contained a level, such as
".arch armv8.2-a", it did validate the name of the level, but it
didn't apply the level to what instructions are allowed. The level
was applied if the directive contained an extra feature enabled,
such as ".arch armv8.2-a+crc" though. It was also applied on the
next ".arch_extension" directive.
This bug, combined with the fact that the same versions of Clang
didn't support the dotprod/i8mm extension names in either
".arch <level>+<feature>" or in ".arch_extension", could lead to
unexepcted build failures.
As the dotprod/i8mm extensions couldn't be enabled dynamically
via the ".arch_extension" directive, someone building ffmpeg could
try to enable them by configuring their build with
--extra-cflags="-march=armv8.6-a".
During configure, we test for support for the i8mm instructions
like this:
# Built with -march=armv8.6-a
.arch armv8.2-a # Has no visible effect here
#.arch_extension i8mm # Omitted as the extension name isn't known
usdot v0.4s, v0.16b, v0.16b
# Successfully assembled as armv8.6-a is the effective level,
# and i8mm is enabled implicitly in armv8.6-a.
Thus, we would enable assembling those instructions. However if
we later check for another extension, such as sve (which those
versions of Clang actually do support), we can later run into the
following situation when building actual code:
# Built with -march=armv8.6-a
.arch armv8.2-a # Has no visible effect here
#.arch_extension i8mm # Omitted as the extension name isn't known
.arch_extension sve # Included as "sve" is as supported extension name
# .arch_extension effectively activates the previous .arch directive,
# so the effective level is armv8.2-a+sve now.
usdot v0.4s, v0.16b, v0.16b
# Fails to build the instructions that require i8mm. Despite the
# configure check, the unrelated ".arch_extension sve" directive
# breaks the functionality of the i8mm feature.
This patch avoids this situation:
- By adding a dummy feature such as "+crc" on the .arch directive
(if supported), we make sure that it does get applied immediately,
avoiding it taking effect spuriously at a later unrelated
".arch_extension" directive.
- By checking for higher arch levels such as armv8.4-a and armv8.6-a,
we can assemble the dotprod and i8mm extensions without the user
needing to pass -march=armv8.6-a. This allows using the dotprod/i8mm
codepaths via runtime detection while keeping the binary runnable
on older versions. I.e. this enables the i8mm codepaths on Apple M2
machines while built with Xcode's Clang.
TL;DR: Enable the I8MM extensions for Apple M2 without the user needing
to do a custom configuration; avoid potential build breakage if a user
does such a custom configuration.
Once Xcode versions that have these issues fixed are prevalent, we
can consider reverting this change.
Signed-off-by: Martin Storsjö <martin@martin.st>
If the scan lines are aligned, we can load each row as a 64-bit value,
thus avoiding segmentation. And then we can factor the conversion or
subtraction.
In principle, the same optimisation should be possible for high depth,
but would require 128-bit elements, for which no FFmpeg CPU flag
exists.
Andreas Rheinhardt
Rémi Denis-Courmont
Niklas Haas
Logan Lyu
Martin Storsjö
Paul B Mahol
James Almer
Kieran Kunhya