[FFmpeg-devel] [PATCH 3/7] proresdec2: use VLC for level instead of EC switch
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Fri Sep 8 11:44:38 EEST 2023
Christophe Gisquet:
> x86/x64: 61/52 -> 55/46
> Around 7-10% speedup.
>
> Run and DC do not lend themselves to such changes, likely because
> their distribution is less skewed, and need larger average vlc read
> iterations.
> ---
> libavcodec/proresdec.h | 1 +
> libavcodec/proresdec2.c | 77 ++++++++++++++++++++++++++++++++++-------
> 2 files changed, 66 insertions(+), 12 deletions(-)
>
> diff --git a/libavcodec/proresdec.h b/libavcodec/proresdec.h
> index 1e48752e6f..7ebacaeb21 100644
> --- a/libavcodec/proresdec.h
> +++ b/libavcodec/proresdec.h
> @@ -22,6 +22,7 @@
> #ifndef AVCODEC_PRORESDEC_H
> #define AVCODEC_PRORESDEC_H
>
> +#define CACHED_BITSTREAM_READER 1
This should be in the commit switching to the cached bitstream reader.
> #include "get_bits.h"
> #include "blockdsp.h"
> #include "proresdsp.h"
> diff --git a/libavcodec/proresdec2.c b/libavcodec/proresdec2.c
> index 65e8b01755..91c689d9ef 100644
> --- a/libavcodec/proresdec2.c
> +++ b/libavcodec/proresdec2.c
> @@ -24,17 +24,17 @@
> * Known FOURCCs: 'apch' (HQ), 'apcn' (SD), 'apcs' (LT), 'apco' (Proxy), 'ap4h' (4444), 'ap4x' (4444 XQ)
> */
>
> -#define CACHED_BITSTREAM_READER 1
> +//#define DEBUG
>
> #include "config_components.h"
>
> #include "libavutil/internal.h"
> #include "libavutil/mem_internal.h"
> +#include "libavutil/thread.h"
>
> #include "avcodec.h"
> #include "codec_internal.h"
> #include "decode.h"
> -#include "get_bits.h"
> #include "hwaccel_internal.h"
> #include "hwconfig.h"
> #include "idctdsp.h"
> @@ -129,8 +129,64 @@ static void unpack_alpha_12(GetBitContext *gb, uint16_t *dst, int num_coeffs,
> }
> }
>
> +#define AC_BITS 12
> +#define PRORES_LEV_BITS 9
> +
> +static const uint8_t ac_info[] = { 0x04, 0x0A, 0x05, 0x06, 0x28, 0x4C };
> +static VLC ac_vlc[6];
> +
> +static av_cold void init_vlcs(void)
> +{
> + int i;
> + for (i = 0; i < sizeof(ac_info); i++) {
FF_ARRAY_ELEMS() is cleaner; also we support and prefer declarations
inside for-loops: for (int i = 0;
> + uint32_t ac_codes[1<<AC_BITS];
> + uint8_t ac_bits[1<<AC_BITS];
> + unsigned int rice_order, exp_order, switch_bits, switch_val;
> + int ac, max_bits = 0, codebook = ac_info[i];
> +
> + /* number of prefix bits to switch between Rice and expGolomb */
> + switch_bits = (codebook & 3);
> + rice_order = codebook >> 5; /* rice code order */
> + exp_order = (codebook >> 2) & 7; /* exp golomb code order */
> +
> + switch_val = (switch_bits+1) << rice_order;
> +
> + // Values are actually transformed, but this is more a wrapping
> + for (ac = 0; ac <1<<AC_BITS; ac++) {
> + int exponent, bits, val = ac;
> + unsigned int code;
> +
> + if (val >= switch_val) {
> + val += (1 << exp_order) - switch_val;
> + exponent = av_log2(val);
> + bits = exponent+1+switch_bits-exp_order/*0*/ + exponent+1/*val*/;
> + code = val;
> + } else if (rice_order) {
> + bits = (val >> rice_order)/*0*/ + 1/*1*/ + rice_order/*val*/;
> + code = (1 << rice_order) | val;
> + } else {
> + bits = val/*0*/ + 1/*1*/;
> + code = 1;
> + }
> + if (bits > max_bits) max_bits = bits;
> + ac_bits [ac] = bits;
> + ac_codes[ac] = code;
> + }
> +
> + ff_free_vlc(ac_vlc+i);
This is unnecessary, as the VLC is initially blank and is not
initialized multiple times.
> +
> + if (init_vlc(ac_vlc+i, PRORES_LEV_BITS, 1<<AC_BITS,
> + ac_bits, 1, 1, ac_codes, 4, 4, 0) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Error for %d(0x%02X), max bits %d\n",
> + i, codebook, max_bits);
> + break; //return AVERROR_BUG;
This is not how you initialize a static table (you miss the
INIT_VLC_USE_NEW_STATIC flag and don't set the static store buffer).
Search for INIT_VLC_STATIC_OVERLONG for an idea of how to do it.
> + }
> + }
> +}
> +
> static av_cold int decode_init(AVCodecContext *avctx)
> {
> + static AVOnce init_static_once = AV_ONCE_INIT;
> int ret = 0;
> ProresContext *ctx = avctx->priv_data;
> uint8_t idct_permutation[64];
> @@ -184,6 +240,9 @@ static av_cold int decode_init(AVCodecContext *avctx)
>
> ctx->pix_fmt = AV_PIX_FMT_NONE;
>
> + // init dc_tables
> + ff_thread_once(&init_static_once, init_vlcs);
> +
> if (avctx->bits_per_raw_sample == 10){
> ctx->unpack_alpha = unpack_alpha_10;
> } else if (avctx->bits_per_raw_sample == 12){
> @@ -510,7 +569,7 @@ static av_always_inline int decode_dc_coeffs(GetBitContext *gb, int16_t *out,
> return 0;
> }
>
> -// adaptive codebook switching lut according to previous run/level values
> +// adaptive codebook switching lut according to previous run values
> static const char run_to_cb[16][4] = {
> { 2, 0, -1, 1 }, { 2, 0, -1, 1 }, { 1, 0, 0, 0 }, { 1, 0, 0, 0 }, { 0, 0, 1, -1 },
> { 1, 1, 1, 0 }, { 1, 1, 1, 0 }, { 1, 1, 1, 0 }, { 1, 1, 1, 0 },
> @@ -518,12 +577,6 @@ static const char run_to_cb[16][4] = {
> { 0, 2, 3, -4 }
> };
>
> -static const char lev_to_cb[10][4] = {
> - { 0, 0, 1, -1 }, { 2, 0, 0, -1 }, { 1, 0, 0, 0 }, { 2, 0, -1, 1 }, { 0, 0, 1, -1 },
> - { 0, 1, 2, -2 }, { 0, 1, 2, -2 }, { 0, 1, 2, -2 }, { 0, 1, 2, -2 },
> - { 0, 2, 3, -4 }
> -};
> -
> static av_always_inline int decode_ac_coeffs(AVCodecContext *avctx, GetBitContext *gb,
> int16_t *out, int blocks_per_slice)
> {
> @@ -540,8 +593,9 @@ static av_always_inline int decode_ac_coeffs(AVCodecContext *avctx, GetBitContex
> block_mask = blocks_per_slice - 1;
>
> for (pos = block_mask;;) {
> + static const uint8_t ctx_to_tbl[] = { 0, 1, 2, 3, 0, 4, 4, 4, 4, 5 };
> + const VLC* tbl = ac_vlc + ctx_to_tbl[FFMIN(level, 9)];
> unsigned int runcb = FFMIN(run, 15);
> - unsigned int levcb = FFMIN(level, 9);
> bits_rem = get_bits_left(gb);
> if (!bits_rem || (bits_rem < 16 && !show_bits(gb, bits_rem)))
> break;
> @@ -554,8 +608,7 @@ static av_always_inline int decode_ac_coeffs(AVCodecContext *avctx, GetBitContex
> return AVERROR_INVALIDDATA;
> }
>
> - DECODE_CODEWORD2(level, lev_to_cb[levcb][0], lev_to_cb[levcb][1],
> - lev_to_cb[levcb][2], lev_to_cb[levcb][3]);
> + level = get_vlc2(gb, tbl->table, PRORES_LEV_BITS, 3);
> level += 1;
>
> i = pos >> log2_block_count;
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