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Code Issues Releases Activity

avcodec/motionpixels: Simplify creating VLC tables

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By using ff_init_vlc_from_lengths(), we do not have to keep track of the
codes themselves, but can offload this to ff_init_vlc_from_lengths().

Furthermore, the old code presumed sizeof(int) == 4; this is no longer
so.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-10-29 11:12:32 +01:00
parent b9dc000679
commit 949367b0ec
1 changed files with 9 additions and 10 deletions
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19
libavcodec/motionpixels.c
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@ -33,7 +33,6 @@
#include "motionpixels_tablegen.h"
typedef struct HuffCode {
int code;
uint8_t size;
uint8_t delta;
} HuffCode;
@ -129,7 +128,7 @@ static void mp_read_changes_map(MotionPixelsContext *mp, GetBitContext *gb, int
}
}
static int mp_get_code(MotionPixelsContext *mp, GetBitContext *gb, int size, int code)
static int mp_get_code(MotionPixelsContext *mp, GetBitContext *gb, int size)
{
while (get_bits1(gb)) {
++size;
@ -137,8 +136,7 @@ static int mp_get_code(MotionPixelsContext *mp, GetBitContext *gb, int size, int
av_log(mp->avctx, AV_LOG_ERROR, "invalid code size %d/%d\n", size, mp->max_codes_bits);
return AVERROR_INVALIDDATA;
}
code <<= 1;
if (mp_get_code(mp, gb, size, code + 1) < 0)
if (mp_get_code(mp, gb, size) < 0)
return AVERROR_INVALIDDATA;
}
if (mp->current_codes_count >= mp->codes_count) {
@ -146,7 +144,6 @@ static int mp_get_code(MotionPixelsContext *mp, GetBitContext *gb, int size, int
return AVERROR_INVALIDDATA;
}
mp->codes[mp->current_codes_count ].code = code;
mp->codes[mp->current_codes_count++].size = size;
return 0;
}
@ -163,7 +160,7 @@ static int mp_read_codes_table(MotionPixelsContext *mp, GetBitContext *gb)
for (i = 0; i < mp->codes_count; ++i)
mp->codes[i].delta = get_bits(gb, 4);
mp->current_codes_count = 0;
if ((ret = mp_get_code(mp, gb, 0, 0)) < 0)
if ((ret = mp_get_code(mp, gb, 0)) < 0)
return ret;
if (mp->current_codes_count < mp->codes_count) {
av_log(mp->avctx, AV_LOG_ERROR, "too few codes\n");
@ -329,10 +326,12 @@ static int mp_decode_frame(AVCodecContext *avctx,
goto end;
if (mp->codes_count > 1) {
ret = ff_init_vlc_sparse(&mp->vlc, mp->max_codes_bits, mp->codes_count,
&mp->codes[0].size, sizeof(HuffCode), 1,
&mp->codes[0].code, sizeof(HuffCode), 4,
&mp->codes[0].delta, sizeof(HuffCode), 1, 0);
/* The entries of the mp->codes array are sorted from right to left
* in the Huffman tree, hence -(int)sizeof(HuffCode). */
ret = ff_init_vlc_from_lengths(&mp->vlc, mp->max_codes_bits, mp->codes_count,
&mp->codes[mp->codes_count - 1].size, -(int)sizeof(HuffCode),
&mp->codes[mp->codes_count - 1].delta, -(int)sizeof(HuffCode), 1,
0, 0, avctx);
if (ret < 0)
goto end;
}