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avcodec/ivi: Avoid reversing BE VLC codes for LE bitstream reader

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Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-10-12 07:45:23 +02:00
parent 3977aeb78c
commit d7a503ecf9
1 changed files with 2 additions and 20 deletions
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22
libavcodec/ivi.c
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@ -35,7 +35,6 @@
#include "avcodec.h" #include "avcodec.h"
#include "get_bits.h" #include "get_bits.h"
#include "internal.h" #include "internal.h"
#include "mathops.h"
#include "ivi.h" #include "ivi.h"
#include "ivi_dsp.h" #include "ivi_dsp.h"
@ -115,23 +114,6 @@ static int ivi_mc(const IVIBandDesc *band, ivi_mc_func mc, ivi_mc_avg_func mc_av
return 0; return 0;
} }
/**
* Reverse "nbits" bits of the value "val" and return the result
* in the least significant bits.
*/
static uint16_t inv_bits(uint16_t val, int nbits)
{
uint16_t res;
if (nbits <= 8) {
res = ff_reverse[val] >> (8 - nbits);
} else
res = ((ff_reverse[val & 0xFF] << 8) +
(ff_reverse[val >> 8])) >> (16 - nbits);
return res;
}
/* /*
* Generate a huffman codebook from the given descriptor * Generate a huffman codebook from the given descriptor
* and convert it into the FFmpeg VLC table. * and convert it into the FFmpeg VLC table.
@ -162,7 +144,7 @@ static int ivi_create_huff_from_desc(const IVIHuffDesc *cb, VLC *vlc, int flag)
if (bits[pos] > IVI_VLC_BITS) if (bits[pos] > IVI_VLC_BITS)
return AVERROR_INVALIDDATA; /* invalid descriptor */ return AVERROR_INVALIDDATA; /* invalid descriptor */
codewords[pos] = inv_bits((prefix | j), bits[pos]); codewords[pos] = prefix | j;
if (!bits[pos]) if (!bits[pos])
bits[pos] = 1; bits[pos] = 1;
@ -172,7 +154,7 @@ static int ivi_create_huff_from_desc(const IVIHuffDesc *cb, VLC *vlc, int flag)
/* number of codewords = pos */ /* number of codewords = pos */
return init_vlc(vlc, IVI_VLC_BITS, pos, bits, 1, 1, codewords, 2, 2, return init_vlc(vlc, IVI_VLC_BITS, pos, bits, 1, 1, codewords, 2, 2,
(flag ? INIT_VLC_USE_NEW_STATIC : 0) | INIT_VLC_LE); (flag ? INIT_VLC_USE_NEW_STATIC : 0) | INIT_VLC_OUTPUT_LE);
} }
av_cold void ff_ivi_init_static_vlc(void) av_cold void ff_ivi_init_static_vlc(void)