The issue is that if a frame has no complex stereo prediction,
the alpha values must all be assumed to be zero if the next frame
has complex prediction and uses delta coding.
The LC part of the decoder combines scalefactor application with
spectrum decoding, and this was the plan here, but that's not possible,
so change the function name.
The issue here is that the spec implied that the offset is done
on the dequantized scalefactor, but in fact, it is done on the
scalefactor offset. Delay dequantizing the scalefactors until
after noise synthesis is performed, and change to apply the
offset onto the offset.
Require that there is a valid layout with a valid number of channels
before accepting nb_elems.
The value is required when flushing.
Thanks to kasper93 for figuring it out.
The issue is that AOT 45 isn't defined anywhere, and looking at the git
blame, it seems to have sprung up through a reordering of the enum,
and adding a hole.
The spec does not define an explicit AOT for SBR and no SBR, and only
uses AOT 42 (previously AOT_USAC_NOSBR), so just rename AOT_USAC to
it and replace its use everywhere.
USAC supports up to 64 audio channels, but puts no limit on the total
number of extensions that may be present. Which may mean that there's
a single audio channel, with 65 thousand extension elements.
We assume that 64 elements is the maximum for now. So check the value.
Some calls to get_escaped_value() specify 0 bits as the third value.
This would result in get_bits(0), which is not a correct usage of the
get_bits API.
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>
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.
This is achieved by using function pointers for AAC SBR functions.
This unfortunately necessitated to use void* in
ff_aac_sbr_apply(_fixed).
Fixes ticket #10999.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This is more in line with how we initialize DSP functions
and avoids tables of function pointers as well as relocations
for these.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This allows to merge it with AACDecDSP.init and remove the latter
(it is called only once anyway); it also allows to make
the fixed/float AACDecDSP and AACDecProc implementations internal
to aacdec_fixed/float.c (which also fixes a violation of our
naming conventions). And it some linker errors when either decoder
is disabled.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
ff_aacdec_common_init_once() already uses its own AVOnce.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
ff_aac_sbr_apply() and ff_aac_sbr_apply_fixed() still used
pointers to INTFLOAT which is float or int depending upon
whether USE_FIXED is set or not; in particular, according
to these declarations both functions have the same type.
But that is wrong and given that aacdec.c sets USE_FIXED,
it sees the wrong type for ff_aac_sbr_apply().
This leads to a -Wlto-type-mismatch warning when using lto [1].
Fix this by avoiding INTFLOAT in aacsbr.h (which also means
that aac_defines.h need not be included there any more).
[1]: https://fate.ffmpeg.org/log.cgi?slot=x86_64-archlinux-gcc-lto&time=20240506022217&log=compile
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
The code was written in 2012, but seems to have been broken
for just as long. Compilation is broken on every MIPS/MIPS64
system with an FPU (which the code depends on).
Lynne
James Almer
Andreas Rheinhardt