Codec IDs have split from `avcodec.h` into `codec_id.h` after commit
c6978418b8.
General documentation contents (which are now in
`general_contents.texi`) have split from the header in `general.texi`
after commit 6accb7718a.
Update the developer documentation to match these changes.
Signed-off-by: Marcus B Spencer <marcus@marcusspencer.xyz>
Fixes "libavcodec/aac/aacdec_usac.c(543): error C2440: 'type cast': cannot convert from 'GetBitContext' to 'GetBitContext'"
from msvc.
Signed-off-by: James Almer <jamrial@gmail.com>
If its not replaced we would have a negative index used in an array potentially
Helps: CID1440385 Negative array index read
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
It seems nothing prevents such overflow even though odd
Fixes: CID1441934 Unintentional integer overflow
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This might not be needed for correctness but it could
help general reproducability of issues
Related to: CID1560037 Uninitialized scalar variable
Related to: CID1560044 Uninitialized scalar variable
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Found while reviewing: CID1500309 Unintentional integer overflow
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This issue cannot happen with the current function parameters
Fixes: CID1500309 Unintentional integer overflow
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit adds a decoder for the frequency-domain part of USAC.
What works:
- Mono
- Stereo (no prediction)
- Stereo (mid/side coding)
- Stereo (complex prediction)
What's left:
- SBR
- Speech coding
Known issues:
- Desync with certain sequences
- Preroll crossover missing (shouldn't matter, bitrate adaptation only)
AAC uses an unconventional system to send scalefactors
(the volume+quantization value for each band).
Each window is split into either 1 or 8 blocks (long vs short),
and transformed separately from one another, with the coefficients
for each being also completely independent. The scalefactors
slightly increase from 64 (long) to 128 (short) to accomodate
better per-block-per-band volume for each window.
To reduce overhead, the codec signals scalefactor sizes in an obtuse way,
where each group's scalefactor types are sent via a variable length decoding,
with a range.
But our decoder was written in a way where those ranges were carried through
the entire decoder, and to actually read them you had to use the range.
Instead of having a dedicated array with a range for each scalefactor,
just let the decoder directly index each scalefactor.
This also switches the form of quantized scalefactors to the format
the spec uses, where for intensity stereo and regular, scalefactors
are stored in a scalefactor - 100 form, rather than as-is.
USAC gets rid of the complex scalefactor handling. This commit permits
for code sharing between both.
The 8x8 pixel arrays are not necessarily aligned to 64 bits, so the
current code leads to Bus error on real hardware. This reproducible
with FATE's vc1_ilaced_twomv test case.
The new "pessimist" code can trivially be shared for 16x16 pixel
arrays so we also do that. FWIW, this also nominally reduces the
hardware requirement from Zve64x to Zve32x.
T-Head C908:
vc1dsp.avg_vc1_mspel_pixels_tab[0][0]_c: 14.7
vc1dsp.avg_vc1_mspel_pixels_tab[0][0]_rvv_i32: 3.5
vc1dsp.avg_vc1_mspel_pixels_tab[1][0]_c: 3.7
vc1dsp.avg_vc1_mspel_pixels_tab[1][0]_rvv_i32: 1.5
SpacemiT X60:
vc1dsp.avg_vc1_mspel_pixels_tab[0][0]_c: 13.0
vc1dsp.avg_vc1_mspel_pixels_tab[0][0]_rvv_i32: 3.0
vc1dsp.avg_vc1_mspel_pixels_tab[1][0]_c: 3.2
vc1dsp.avg_vc1_mspel_pixels_tab[1][0]_rvv_i32: 1.2
