Re: [FFmpeg-devel] [PATCH 05/35] avcodec/proresenc_kostya: remove one LUT indirection for run/level to codebook mapping

[Stefano Sabatini <stefasab@gmail.com>]

On date Monday 2023-12-11 02:35:06 +0100, Clément Bœsch wrote:
> This is following the same logic as proresenc_anatoliy.
> ---
>  libavcodec/proresenc_kostya.c | 47 +++++++++++------------------------
>  1 file changed, 14 insertions(+), 33 deletions(-)
> 
> diff --git a/libavcodec/proresenc_kostya.c b/libavcodec/proresenc_kostya.c
> index 6e1d5a0cef..f883ab550b 100644
> --- a/libavcodec/proresenc_kostya.c
> +++ b/libavcodec/proresenc_kostya.c
> @@ -142,25 +142,6 @@ static const uint8_t prores_dc_codebook[4] = {
>      0x70  // rice_order = 3, exp_golomb_order = 4, switch_bits = 0
>  };
>  
> -static const uint8_t prores_ac_codebook[7] = {
> -    0x04, // rice_order = 0, exp_golomb_order = 1, switch_bits = 0
> -    0x28, // rice_order = 1, exp_golomb_order = 2, switch_bits = 0
> -    0x4C, // rice_order = 2, exp_golomb_order = 3, switch_bits = 0
> -    0x05, // rice_order = 0, exp_golomb_order = 1, switch_bits = 1
> -    0x29, // rice_order = 1, exp_golomb_order = 2, switch_bits = 1
> -    0x06, // rice_order = 0, exp_golomb_order = 1, switch_bits = 2
> -    0x0A, // rice_order = 0, exp_golomb_order = 2, switch_bits = 2
> -};
> -
> -/**
> - * Lookup tables for adaptive switching between codebooks
> - * according with previous run/level value.
> - */
> -static const uint8_t prores_run_to_cb_index[16] =
> -    { 5, 5, 3, 3, 0, 4, 4, 4, 4, 1, 1, 1, 1, 1, 1, 2 };
> -
> -static const uint8_t prores_lev_to_cb_index[10] = { 0, 6, 3, 5, 0, 1, 1, 1, 1, 2 };
> -
>  #define NUM_MB_LIMITS 4
>  static const int prores_mb_limits[NUM_MB_LIMITS] = {
>      1620, // up to 720x576
> @@ -461,12 +442,12 @@ static void encode_acs(PutBitContext *pb, int16_t *blocks,
>                         const uint8_t *scan, const int16_t *qmat)
>  {
>      int idx, i;
> -    int run, level, run_cb, lev_cb;
> +    int prev_run = 4;
> +    int prev_level = 2;
> +    int run, level;
>      int max_coeffs, abs_level;
>  
>      max_coeffs = blocks_per_slice << 6;
> -    run_cb     = prores_run_to_cb_index[4];
> -    lev_cb     = prores_lev_to_cb_index[2];
>      run        = 0;
>  
>      for (i = 1; i < 64; i++) {
> @@ -474,13 +455,13 @@ static void encode_acs(PutBitContext *pb, int16_t *blocks,
>              level = blocks[idx] / qmat[scan[i]];
>              if (level) {
>                  abs_level = FFABS(level);
> -                encode_vlc_codeword(pb, prores_ac_codebook[run_cb], run);
> -                encode_vlc_codeword(pb, prores_ac_codebook[lev_cb],
> +                encode_vlc_codeword(pb, ff_prores_run_to_cb[prev_run], run);
> +                encode_vlc_codeword(pb, ff_prores_lev_to_cb[prev_level],
>                                      abs_level - 1);
>                  put_sbits(pb, 1, GET_SIGN(level));
>  
> -                run_cb = prores_run_to_cb_index[FFMIN(run, 15)];
> -                lev_cb = prores_lev_to_cb_index[FFMIN(abs_level, 9)];
> +                prev_run   = FFMIN(run, 15);
> +                prev_level = FFMIN(abs_level, 9);
>                  run    = 0;
>              } else {
>                  run++;
> @@ -699,13 +680,13 @@ static int estimate_acs(int *error, int16_t *blocks, int blocks_per_slice,
>                          const uint8_t *scan, const int16_t *qmat)
>  {
>      int idx, i;
> -    int run, level, run_cb, lev_cb;
> +    int prev_run = 4;
> +    int prev_level = 2;
> +    int run, level;
>      int max_coeffs, abs_level;
>      int bits = 0;
>  
>      max_coeffs = blocks_per_slice << 6;
> -    run_cb     = prores_run_to_cb_index[4];
> -    lev_cb     = prores_lev_to_cb_index[2];
>      run        = 0;
>  
>      for (i = 1; i < 64; i++) {
> @@ -714,12 +695,12 @@ static int estimate_acs(int *error, int16_t *blocks, int blocks_per_slice,
>              *error += FFABS(blocks[idx]) % qmat[scan[i]];
>              if (level) {
>                  abs_level = FFABS(level);
> -                bits += estimate_vlc(prores_ac_codebook[run_cb], run);
> -                bits += estimate_vlc(prores_ac_codebook[lev_cb],
> +                bits += estimate_vlc(ff_prores_run_to_cb[prev_run], run);
> +                bits += estimate_vlc(ff_prores_lev_to_cb[prev_level],
>                                       abs_level - 1) + 1;
>  
> -                run_cb = prores_run_to_cb_index[FFMIN(run, 15)];
> -                lev_cb = prores_lev_to_cb_index[FFMIN(abs_level, 9)];
> +                prev_run   = FFMIN(run, 15);
> +                prev_level = FFMIN(abs_level, 9);
>                  run    = 0;
>              } else {
>                  run++;

LGTM.
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