[FFmpeg-devel] [PATCH 3/4] avcodec/ffv1: Fix remap and float with golomb rice

Lynne dev at lynne.ee
Mon Mar 10 20:41:26 EET 2025


On 09/03/2025 23:58, Michael Niedermayer wrote:
> Sponsored-by: Sovereign Tech Fund
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>   libavcodec/ffv1dec.c          | 37 +++++++++++++++++++++++++
>   libavcodec/ffv1dec_template.c | 27 ------------------
>   libavcodec/ffv1enc.c          | 42 ++++++++++++++++++++++++++++
>   libavcodec/ffv1enc_template.c | 52 -----------------------------------
>   4 files changed, 79 insertions(+), 79 deletions(-)
> 
> diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
> index 49a363208db..9738e4e9c9f 100644
> --- a/libavcodec/ffv1dec.c
> +++ b/libavcodec/ffv1dec.c
> @@ -244,6 +244,37 @@ static void slice_set_damaged(FFV1Context *f, FFV1SliceContext *sc)
>           f->frame_damaged = 1;
>   }
>   
> +static int decode_remap(FFV1Context *f, FFV1SliceContext *sc)
> +{
> +    int transparency = f->transparency;
> +
> +    for (int p= 0; p<3 + transparency; p++) {
> +        int j = 0;
> +        int lu = 0;
> +        uint8_t state[2][32];
> +        memset(state, 128, sizeof(state));
> +
> +        for (int i= 0; i<65536; i++) {
> +            int run = get_symbol_inline(&sc->c, state[lu], 0);
> +            if (run > 65536U - i)
> +                return AVERROR_INVALIDDATA;
> +            if (lu) {
> +                lu ^= !run;
> +                while (run--) {
> +                    sc->fltmap[p][j++] = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> +                    i++;
> +                }
> +            } else {
> +                i += run;
> +                if (i != 65536)
> +                    sc->fltmap[p][j++] = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> +                lu ^= !run;
> +            }
> +        }
> +    }
> +    return 0;
> +}
> +
>   static int decode_slice(AVCodecContext *c, void *arg)
>   {
>       FFV1Context *f    = c->priv_data;
> @@ -289,6 +320,12 @@ static int decode_slice(AVCodecContext *c, void *arg)
>       chroma_width  = AV_CEIL_RSHIFT(width,  f->chroma_h_shift);
>       chroma_height = AV_CEIL_RSHIFT(height, f->chroma_v_shift);
>   
> +    if (sc->remap) {
> +        ret = decode_remap(f, sc);
> +        if (ret < 0)
> +            return ret;
> +    }
> +
>       if (ac == AC_GOLOMB_RICE) {
>           if (f->combined_version >= 0x30002)
>               get_rac(&sc->c, (uint8_t[]) { 129 });
> diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c
> index 818f12f865d..f9499931b1d 100644
> --- a/libavcodec/ffv1dec_template.c
> +++ b/libavcodec/ffv1dec_template.c
> @@ -167,33 +167,6 @@ static int RENAME(decode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc,
>   
>       memset(RENAME(sc->sample_buffer), 0, 8 * (w + 6) * sizeof(*RENAME(sc->sample_buffer)));
>   
> -    if (sc->remap) {
> -        for (int p= 0; p<3 + transparency; p++) {
> -            int j = 0;
> -            int lu = 0;
> -            uint8_t state[2][32];
> -            memset(state, 128, sizeof(state));
> -
> -            for (int i= 0; i<65536; i++) {
> -                int run = get_symbol_inline(&sc->c, state[lu], 0);
> -                if (run > 65536U - i)
> -                    return AVERROR_INVALIDDATA;
> -                if (lu) {
> -                    lu ^= !run;
> -                    while (run--) {
> -                        sc->fltmap[p][j++] = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> -                        i++;
> -                    }
> -                } else {
> -                    i += run;
> -                    if (i != 65536)
> -                        sc->fltmap[p][j++] = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> -                    lu ^= !run;
> -                }
> -            }
> -        }
> -    }
> -
>       for (y = 0; y < h; y++) {
>           for (p = 0; p < 3 + transparency; p++) {
>               int ret;
> diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c
> index 11753386724..f3041219b71 100644
> --- a/libavcodec/ffv1enc.c
> +++ b/libavcodec/ffv1enc.c
> @@ -1110,6 +1110,36 @@ static void choose_rct_params(const FFV1Context *f, FFV1SliceContext *sc,
>       sc->slice_rct_ry_coef = rct_y_coeff[best][0];
>   }
>   
> +static void encode_remap(FFV1Context *f, FFV1SliceContext *sc)
> +{
> +    int transparency = f->transparency;
> +
> +    for (int p= 0; p<3 + transparency; p++) {
> +        int j = 0;
> +        int lu = 0;
> +        uint8_t state[2][32];
> +        int run = 0;
> +        memset(state, 128, sizeof(state));
> +        for (int i= 0; i<65536; i++) {
> +            int ri = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> +            int u = sc->fltmap[p][ri];
> +            sc->fltmap[p][ri] = j;
> +            j+= u;
> +
> +            if (lu == u) {
> +                run ++;
> +            } else {
> +                put_symbol_inline(&sc->c, state[lu], run, 0, NULL, NULL);
> +                if (run == 0)
> +                    lu = u;
> +                run = 0;
> +            }
> +        }
> +        if (run)
> +            put_symbol(&sc->c, state[lu], run, 0);
> +    }
> +}
> +
>   static int encode_slice(AVCodecContext *c, void *arg)
>   {
>       FFV1SliceContext *sc = arg;
> @@ -1146,6 +1176,18 @@ retry:
>       if (f->version > 2) {
>           encode_slice_header(f, sc);
>       }
> +
> +    if (sc->remap) {
> +        if (f->colorspace == 0) {
> +            av_assert0(0);
> +        } else if (f->use32bit) {
> +            load_rgb_frame32(f, sc, planes, width, height, p->linesize);
> +        } else
> +            load_rgb_frame  (f, sc, planes, width, height, p->linesize);
> +
> +        encode_remap(f, sc);
> +    }
> +
>       if (ac == AC_GOLOMB_RICE) {
>           sc->ac_byte_count = f->version > 2 || (!x && !y) ? ff_rac_terminate(&sc->c, f->version > 2) : 0;
>           init_put_bits(&sc->pb,
> diff --git a/libavcodec/ffv1enc_template.c b/libavcodec/ffv1enc_template.c
> index 8cc8876411b..d8160282b2e 100644
> --- a/libavcodec/ffv1enc_template.c
> +++ b/libavcodec/ffv1enc_template.c
> @@ -197,58 +197,6 @@ static int RENAME(encode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc,
>       memset(RENAME(sc->sample_buffer), 0, ring_size * MAX_PLANES *
>              (w + 6) * sizeof(*RENAME(sc->sample_buffer)));
>   
> -    if (sc->remap) {
> -        memset(sc->fltmap, 0, sizeof(sc->fltmap));
> -
> -        for (y = 0; y < h; y++) {
> -            for (x = 0; x < w; x++) {
> -                int b, g, r, av_uninit(a);
> -
> -                if (sizeof(TYPE) == 4 || transparency) {
> -                    g = *((const uint16_t *)(src[0] + x*2 + stride[0]*y));
> -                    b = *((const uint16_t *)(src[1] + x*2 + stride[1]*y));
> -                    r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y));
> -                    if (transparency)
> -                        a = *((const uint16_t *)(src[3] + x*2 + stride[3]*y));
> -                } else {
> -                    b = *((const uint16_t *)(src[0] + x*2 + stride[0]*y));
> -                    g = *((const uint16_t *)(src[1] + x*2 + stride[1]*y));
> -                    r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y));
> -                }
> -
> -                sc->fltmap[0][r] = 1;
> -                sc->fltmap[1][g] = 1;
> -                sc->fltmap[2][b] = 1;
> -                if (transparency)
> -                    sc->fltmap[3][a] = 1;
> -            }
> -        }
> -        for (int p= 0; p<3 + transparency; p++) {
> -            int j = 0;
> -            int lu = 0;
> -            uint8_t state[2][32];
> -            int run = 0;
> -            memset(state, 128, sizeof(state));
> -            for (int i= 0; i<65536; i++) {
> -                int ri = i ^ ((i&0x8000) ? 0 : 0x7FFF);
> -                int u = sc->fltmap[p][ri];
> -                sc->fltmap[p][ri] = j;
> -                j+= u;
> -
> -                if (lu == u) {
> -                    run ++;
> -                } else {
> -                    put_symbol_inline(&sc->c, state[lu], run, 0, NULL, NULL);
> -                    if (run == 0)
> -                        lu = u;
> -                    run = 0;
> -                }
> -            }
> -            if (run)
> -                put_symbol(&sc->c, state[lu], run, 0);
> -        }
> -    }
> -
>       for (y = 0; y < h; y++) {
>           for (i = 0; i < ring_size; i++)
>               for (p = 0; p < MAX_PLANES; p++)

That's a lot better and cleaner than the current code.
LGTM.


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