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Code Issues Releases Activity

avcodec/sheervideo: Simplify creating VLC table

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ff_init_vlc_from_lengths() can be used to offload the computation
of the codes; it also needn't check whether the codes are already
properly ordered (they are).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-11-01 01:21:06 +01:00
parent f31bf4a1f9
commit d4a4a6747d
1 changed files with 4 additions and 9 deletions
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13
libavcodec/sheervideo.c
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@ -1784,11 +1784,10 @@ static void decode_rgb(AVCodecContext *avctx, AVFrame *p, GetBitContext *gb)
static av_cold int build_vlc(VLC *vlc, const SheerTable *table) static av_cold int build_vlc(VLC *vlc, const SheerTable *table)
{ {
const uint8_t *cur = table->lens; const uint8_t *cur = table->lens;
uint16_t codes[1024];
uint8_t lens[1024]; uint8_t lens[1024];
unsigned count = 0; unsigned count = 0;
for (unsigned step = 1, len = 1, index = 0; len > 0; len += step) { for (int step = 1, len = 1; len > 0; len += step) {
unsigned new_count = count; unsigned new_count = count;
if (len == 16) { if (len == 16) {
@ -1797,17 +1796,13 @@ static av_cold int build_vlc(VLC *vlc, const SheerTable *table)
} else } else
new_count += *cur++; new_count += *cur++;
for (; count < new_count; count++) { for (; count < new_count; count++)
codes[count] = index >> (32 - len);
index += 1U << (32 - len);
lens[count] = len; lens[count] = len;
} }
}
ff_free_vlc(vlc); ff_free_vlc(vlc);
return init_vlc(vlc, SHEER_VLC_BITS, count, return ff_init_vlc_from_lengths(vlc, SHEER_VLC_BITS, count,
lens, sizeof(*lens), sizeof(*lens), lens, sizeof(*lens), NULL, 0, 0, 0, 0, NULL);
codes, sizeof(*codes), sizeof(*codes), 0);
} }
static int decode_frame(AVCodecContext *avctx, static int decode_frame(AVCodecContext *avctx,