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Code Issues Releases Activity

avcodec/vc2enc: Use LUT to assemble interleaved golomb code

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Up until now, the encoder processed only one bit at a time.
With this patch, it is eight bits.

Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-03-12 03:26:09 +01:00
parent 0b097ed9f1
commit b0af322654
1 changed files with 32 additions and 11 deletions
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47
libavcodec/vc2enc.c
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@ -22,6 +22,7 @@
#include "libavutil/mem.h"
#include "libavutil/pixdesc.h"
#include "libavutil/opt.h"
#include "libavutil/thread.h"
#include "libavutil/version.h"
#include "codec_internal.h"
#include "dirac.h"
@ -186,22 +187,39 @@ typedef struct VC2EncContext {
enum DiracParseCodes last_parse_code;
} VC2EncContext;
static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
{
int i;
int bits = av_log2(++val);
unsigned topbit = 1 << bits;
uint64_t pbits = 0;
/// x_k x_{k-1} ... x_0 -> 0 x_k 0 x_{k - 1} ... 0 x_0
static uint16_t interleaved_ue_golomb_tab[256];
/// 1 x_{k-1} ... x_0 -> 0 0 0 x_{k - 1} ... 0 x_0
static uint16_t top_interleaved_ue_golomb_tab[256];
/// 1 x_{k-1} ... x_0 -> 2 * k
static uint8_t golomb_len_tab[256];
for (i = 0; i < bits; i++) {
topbit >>= 1;
av_assert2(pbits <= UINT64_MAX>>3);
pbits <<= 2;
if (val & topbit)
pbits |= 0x1;
static av_cold void vc2_init_static_data(void)
{
interleaved_ue_golomb_tab[1] = 1;
for (unsigned i = 2; i < 256; ++i) {
golomb_len_tab[i] = golomb_len_tab[i >> 1] + 2;
interleaved_ue_golomb_tab[i] = (interleaved_ue_golomb_tab[i >> 1] << 2) | (i & 1);
top_interleaved_ue_golomb_tab[i] = interleaved_ue_golomb_tab[i] ^ (1 << golomb_len_tab[i]);
}
}
put_bits63(pb, 2 * bits + 1, (pbits << 1) | 1);
static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
{
uint64_t pbits = 1;
int bits = 1;
++val;
while (val >> 8) {
pbits |= (uint64_t)interleaved_ue_golomb_tab[val & 0xff] << bits;
val >>= 8;
bits += 16;
}
pbits |= (uint64_t)top_interleaved_ue_golomb_tab[val] << bits;
bits += golomb_len_tab[val];
put_bits63(pb, bits, pbits);
}
static av_always_inline int count_vc2_ue_uint(uint32_t val)
@ -1003,6 +1021,7 @@ static av_cold int vc2_encode_end(AVCodecContext *avctx)
static av_cold int vc2_encode_init(AVCodecContext *avctx)
{
static AVOnce init_static_once = AV_ONCE_INIT;
Plane *p;
SubBand *b;
int i, level, o, shift;
@ -1165,6 +1184,8 @@ static av_cold int vc2_encode_init(AVCodecContext *avctx)
}
}
ff_thread_once(&init_static_once, vc2_init_static_data);
return 0;
}