VLC_MULTI_ELEM contains an uint8_t array that is supposed
to be treated as an array of uint16_t when the used symbols
have a size of two; otherwise it should be treated as just
an array of uint8_t, but it was not always treated that way:
vlc_multi_gen() initialized the first entry of the array
by writing the symbol via AV_WN16; on big endian systems,
the intended value was instead written into the second entry
of the array (where it would likely be overwritten lateron
during initialization).
read_vlc_multi() also treated this case incorrectly: In case
the code is so long that it needs a classical multi-stage lookup,
the symbol has been written to the destination as if via AV_WN16.
On little endian systems, this sets the correct first symbol and
clobbers (zeroes) the next one, but the next one will be overwritten
lateron anyway, so it won't be recognized. But on big-endian systems,
the first symbol will be set to zero and the actually read symbol
will be put into the slot for the next one (where it will be overwritten
lateron).
This commit fixes this; this fixes the magicyuv and utvideo FATE-tests
on big endian arches.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Therefore use a proper prefix for this API, e.g.
ff_init_vlc_sparse -> ff_vlc_init_sparse
ff_free_vlc -> ff_vlc_free
INIT_VLC_LE -> VLC_INIT_LE
INIT_VLC_USE_NEW_STATIC -> VLC_INIT_USE_STATIC
(The ancient INIT_VLC_USE_STATIC has been removed
in 595324e143, so that
the NEW has been dropped.)
Finally, reorder the flags and change their values
accordingly.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Due to non-byte-alignment a read of 32 bits guarantees only
25 usable bits; therefore get_bits_long() (which is used to
potentially read more than 25 bits) performs two reads in case
it needs to read more than 25 bits and combines the result.
Yet this is not necessary: One can just read 64 bits at a time
to get 32 usable bits (57 would be possible). This commit does so.
This reduced the size of .text by 30144B for GCC 11.4 and 5648B
for Clang 14 (both with -O3).
(get_bits_long() is a building block of show_bits_long()
and get_ue_golomb_long(), so this patch affects these, too.)
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
bits_*_signed(0) will currently invoke an undefined shift by
8 * sizeof(int).
Add bits_*_signed_nz() that only works for n>0, analogous to
bits_read_nz(). Add an explicit check for n=0 in bits_*_signed().
Found-by: James Almer
In C, qualifiers for arrays are broken:
const VLC_TYPE (*foo)[2] is a pointer to an array of two const VLC_TYPE
elements and unfortunately this is not compatible with a pointer
to a const array of two VLC_TYPE, because the latter does not exist
as array types are never qualified (the qualifier applies to the base
type instead). This is the reason why get_vlc2() doesn't accept
a const VLC table despite not modifying the table at all, as
there is no automatic conversion from VLC_TYPE (*)[2] to
const VLC_TYPE (*)[2].
Fix this by using a structure VLCElem for the VLC table.
This also has the advantage of making it clear which
element is which.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This decoder can decode all existing SpeedHQ formats (SHQ0–5, 7, and 9),
including correct decoding of the alpha channel.
1080p is decoded in 142 fps on one core of my i7-4600U (2.1 GHz Haswell),
about evenly split between bitstream reader and IDCT. There is currently
no attempt at slice or frame threading, even though the format trivially
supports both.
NewTek very helpfully provided a full set of SHQ samples, as well as
source code for an SHQ2 encoder (not included) and assistance with
understanding some details of the format.
Use the newly created vlc.h directly instead of including get_bits when needed.
The VLC and RL_VLC_ELEM structures are independent from the bitreader.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
This can be used to simplify code in a couple of places.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Andreas Rheinhardt
James Almer
Paul B Mahol
Anton Khirnov
Martijn van Beurden
Ramiro Polla
Marton Balint
Michael Niedermayer
Steinar H. Gunderson
Clément Bœsch
Diego Biurrun
Alexandra Hájková
Vittorio Giovara
Andreas Cadhalpun
Kieran Kunhya
Michael Niedermayer
Timothy Gu
Matthew Lindner
Reimar Döffinger