[FFmpeg-devel] [PATCH 2/2] avcodec/ffv1: Store remap flag per slice

[Michael Niedermayer]

This allows switching it on conditionally and also for non float,
it may improve compression for RGB data that was paletted
or other synthetic images

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/ffv1.h             | 1 +
 libavcodec/ffv1dec.c          | 8 ++++++++
 libavcodec/ffv1dec_template.c | 4 ++--
 libavcodec/ffv1enc.c          | 3 +++
 libavcodec/ffv1enc_template.c | 4 ++--
 5 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
index bf49f613a75..3254ae1b56b 100644
--- a/libavcodec/ffv1.h
+++ b/libavcodec/ffv1.h
@@ -83,6 +83,7 @@ typedef struct FFV1SliceContext {
     int slice_coding_mode;
     int slice_rct_by_coef;
     int slice_rct_ry_coef;
+    int remap;
 
     // RefStruct reference, array of MAX_PLANES elements
     PlaneContext *plane;
diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index def95ff411f..db3eedcdc3f 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -248,6 +248,14 @@ static int decode_slice_header(const FFV1Context *f,
                 return AVERROR_INVALIDDATA;
             }
         }
+        if (f->combined_version >= 0x40004) {
+            sc->remap = get_symbol(c, state, 0);
+            if (sc->remap > 1 ||
+                sc->remap == 1 && !f->flt) {
+                av_log(f->avctx, AV_LOG_ERROR, "unsupported remap %d\n", sc->remap);
+                return AVERROR_INVALIDDATA;
+            }
+        }
     }
 
     return 0;
diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c
index a419aca8584..1fa9933d984 100644
--- a/libavcodec/ffv1dec_template.c
+++ b/libavcodec/ffv1dec_template.c
@@ -155,7 +155,7 @@ 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 (f->flt) {
+    if (sc->remap) {
         for (int p= 0; p<3 + transparency; p++) {
             int j = 0;
             int lu = 0;
@@ -199,7 +199,7 @@ static int RENAME(decode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc,
                 b += g;
                 r += g;
             }
-            if (f->flt) {
+            if (sc->remap) {
                 r = sc->fltmap[0][r];
                 g = sc->fltmap[1][g];
                 b = sc->fltmap[2][b];
diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c
index 8e9f41fea8f..eba2aab4866 100644
--- a/libavcodec/ffv1enc.c
+++ b/libavcodec/ffv1enc.c
@@ -946,6 +946,8 @@ static int encode_init_internal(AVCodecContext *avctx)
         }
 
         ff_build_rac_states(&s->slices[j].c, 0.05 * (1LL << 32), 256 - 8);
+
+        s->slices[j].remap = s->flt;
     }
 
     if ((ret = ff_ffv1_init_slices_state(s)) < 0)
@@ -1000,6 +1002,7 @@ static void encode_slice_header(FFV1Context *f, FFV1SliceContext *sc)
             put_symbol(c, state, sc->slice_rct_by_coef, 0);
             put_symbol(c, state, sc->slice_rct_ry_coef, 0);
         }
+        put_symbol(c, state, sc->remap, 0);
     }
 }
 
diff --git a/libavcodec/ffv1enc_template.c b/libavcodec/ffv1enc_template.c
index 0d1b0a28432..4c7cd2e647c 100644
--- a/libavcodec/ffv1enc_template.c
+++ b/libavcodec/ffv1enc_template.c
@@ -148,7 +148,7 @@ 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 (f->flt) {
+    if (sc->remap) {
         memset(sc->fltmap, 0, sizeof(sc->fltmap));
 
         for (y = 0; y < h; y++) {
@@ -221,7 +221,7 @@ static int RENAME(encode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc,
                 r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y));
             }
 
-            if (f->flt) {
+            if (sc->remap) {
                 r = sc->fltmap[0][r];
                 g = sc->fltmap[1][g];
                 b = sc->fltmap[2][b];
-- 
2.48.1