The layout for the frame flags is as follow:
chroma_format u(2)
reserved u(2)
interlace_mode u(2)
reserved u(2)
chroma_format has 2 allowed values:
0: reserved
1: reserved
2: 4:2:2
3: 4:4:4
interlace_mode has 3 allowed values:
0: progressive
1: tff
2: bff
3: reserved
0x80 is what we expect for "422 not interlaced", and the extra 0x2 from
0x82 is actually writing into the reserved bits.
This byte represents 4 reserved bits followed by 4 alpha_channel_type bits.
alpha_channel_type currently has 3 differents defined values: 0 (no
alpha), 1 (8b alpha), and 2 (16b alpha), all the other values are
reserved. The 4 initial reserved bits are expected to be 0.
This byte represents 4 reserved bits followed by 4 alpha_channel_type bits.
alpha_channel_type currently has 3 differents defined values: 0 (no
alpha), 1 (8b alpha), and 2 (16b alpha), all the other values are
reserved. This part is correctly written (alpha_bits>>3 does the correct
thing), but the 4 initial bits are reserved.
Quoting SMPTE RDD 36:2015:
A decoder shall abort if it encounters a bitstream with an unsupported
bitstream_version value. If 0, the value of the chroma_format syntax
element shall be 2 (4:2:2 sampling) and the value of the
alpha_channel_type element shall be 0 (no encoded alpha); if 1, any
permissible value may be used for those syntax elements.
So if we're not in 4:2:2 or if there is alpha, we are not allowed to use
version 0.
Quoting SMPTE RDD 36:2015:
A decoder shall abort if it encounters a bitstream with an unsupported
bitstream_version value. If 0, the value of the chroma_format syntax
element shall be 2 (4:2:2 sampling) and the value of the
alpha_channel_type element shall be 0 (no encoded alpha); if 1, any
permissible value may be used for those syntax elements.
So if we're not in 4:2:2 or if there is alpha, we are not allowed to use
version 0.
FIx warnings (soon to be errors in GCC 14, already so in Clang 15):
```
src/libavcodec/vulkan_av1.c: In function ‘vk_av1_create_params’:
src/libavcodec/vulkan_av1.c:183:43: error: initialization of ‘long long unsigned int’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
183 | .videoSessionParametersTemplate = NULL,
| ^~~~
src/libavcodec/vulkan_av1.c:183:43: note: (near initialization for ‘(anonymous).videoSessionParametersTemplate’)
```
Use Vulkan's VK_NULL_HANDLE instead of bare NULL.
Fix Trac ticket #10724.
Was reported downstream in Gentoo at https://bugs.gentoo.org/919067.
Signed-off-by: Sam James <sam@gentoo.org>
These functions encode a slice of alpha (1 to 8 macroblocks) which are
expected to be encoded as a repeated sequence of "[diff][run-1]", where
diff is the running difference of the alpha value and run is how many
times that value is expected to be duplicated (within the limit of a
grand total of 2048 unpacked samples, corresponding to a slice of 8 MB).
Even when run==0 (the run variable semantic is actually "run minus 1"),
there is always a diff previously encoded that needs a counter of at
least 1. This means we need to call put_alpha_run() unconditionally at
the end of the bitstream to account for the last running diff.
This commit fixes glitchy playbacks on QuickTime with M2 and M3 hardware
(but not M1 for some mysterious reason) with files generated with
commands such as:
ffmpeg -f lavfi -i testsrc2=d=5:s=912x320,chromakey -c:v prores_aw -profile:v 4 -y aw.mov
ffmpeg -f lavfi -i testsrc2=d=5:s=912x320,chromakey -c:v prores_ks -profile:v 4444 -y ks.mov
The glitch expresses itself deterministically as blinking black
rectangles on random frames (for example on frame 21, 54, 71, 79, ...).
Even with the proresdec from FFmpeg, overreads actually happens while
reading the run-minus-1 value (around val = get_bits(gb, 4) in
unpack_alpha()). This doesn't seem to cause any particular issue because
it simply overreads into the next slice, and because the decoder is
resilient, but it's still a problem.
The investigation leading to this fix was made possible because of paid
work for Jitter (https://jitter.video).
Fixes ticket #10255.
