[FFmpeg-devel] [PATCH] avcodec/ffv1: NOT FOR GIT experiment seperately coding sign bits of float16

[Michael Niedermayer]

The float sign bits seem to take about 1% of space in the compressed
bitstream. Storing it separately in a RC symbol each is worse
---
 libavcodec/ffv1.c             |  1 +
 libavcodec/ffv1.h             |  1 +
 libavcodec/ffv1enc_template.c | 24 ++++++++++++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/libavcodec/ffv1.c b/libavcodec/ffv1.c
index f303ed769f0..a9fa2959087 100644
--- a/libavcodec/ffv1.c
+++ b/libavcodec/ffv1.c
@@ -105,6 +105,7 @@ av_cold int ff_ffv1_init_slice_state(const FFV1Context *f,
             sc->c.zero_state[256 - j] = 256 - sc->c.one_state[j];
         }
     }
+    memset(sc->newstate, 128, sizeof(sc->newstate));
 
     return 0;
 }
diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
index 2c2df154037..f2cc5a63d5e 100644
--- a/libavcodec/ffv1.h
+++ b/libavcodec/ffv1.h
@@ -104,6 +104,7 @@ typedef struct FFV1SliceContext {
             uint64_t (*rc_stat2[MAX_QUANT_TABLES])[32][2];
         };
     };
+    uint8_t newstate[65536];
 } FFV1SliceContext;
 
 typedef struct FFV1Context {
diff --git a/libavcodec/ffv1enc_template.c b/libavcodec/ffv1enc_template.c
index bc14926ab95..c6535373024 100644
--- a/libavcodec/ffv1enc_template.c
+++ b/libavcodec/ffv1enc_template.c
@@ -62,9 +62,17 @@ RENAME(encode_line)(FFV1Context *f, FFV1SliceContext *sc,
     for (x = 0; x < w; x++) {
         int diff, context;
 
+        int signstate = (1&(sample[0][x-1]>>15)) + 2*(sample[1][x]>>15) + 4*(sample[1][x-1]>>15) + 8*(sample[1][x+1]>>15);
+        put_rac(c, sc->newstate+signstate, 1&(sample[0][x]>>15));
+
         context = RENAME(get_context)(f->quant_tables[p->quant_table_index],
                                       sample[0] + x, sample[1] + x, sample[2] + x);
-        diff    = sample[0][x] - RENAME(predict)(sample[0] + x, sample[1] + x);
+        int64_t  L = (sample[0][x-1]) & 0x7FFF;
+        int64_t  T = (sample[1][x]) & 0x7FFF;
+        int64_t LT = (sample[1][x-1]) & 0x7FFF;
+
+        diff    = (sample[0][x] & 0x7FFF) - mid_pred((L), (L + T - LT), (T));
+//        diff    = sample[0][x] - RENAME(predict)(sample[0] + x, sample[1] + x);
 
         if (context < 0) {
             context = -context;
@@ -180,13 +188,13 @@ static int RENAME(encode_rgb_frame)(FFV1Context *f, FFV1SliceContext *sc,
                 r = *((const uint16_t *)(src[2] + x*2 + stride[2]*y));
             }
 
-            if (sc->slice_coding_mode != 1) {
-                b -= g;
-                r -= g;
-                g += (b * sc->slice_rct_by_coef + r * sc->slice_rct_ry_coef) >> 2;
-                b += offset;
-                r += offset;
-            }
+//             if (sc->slice_coding_mode != 1) {
+//                 b -= g;
+//                 r -= g;
+//                 g += (b * sc->slice_rct_by_coef + r * sc->slice_rct_ry_coef) >> 2;
+//                 b += offset;
+//                 r += offset;
+//             }
 
             sample[0][0][x] = g;
             sample[1][0][x] = b;
-- 
2.48.1