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 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>
Lynne
Andreas Rheinhardt