[FFmpeg-devel] [PATCH] vc2enc: implement adaptive quantization

[Rostislav Pehlivanov]

Actually this breaks lossless mode, made the following 2 changes locally:
	-fix lossless mode
	-set default slice sizes to 32x16 (greater quality and speed)
---
 libavcodec/vc2enc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libavcodec/vc2enc.c b/libavcodec/vc2enc.c
index addc5d4..9ff867d 100644
--- a/libavcodec/vc2enc.c
+++ b/libavcodec/vc2enc.c
@@ -687,7 +687,7 @@ static int calc_slice_sizes(VC2EncContext *s)
 {
     SliceArgs *enc_args = s->slice_args;
     SliceArgs **tmp = &s->slice_ratings[s->num_x*s->num_y];
-    int i, slice_x, slice_y, bytes_left = 0;
+    int i, slice_x, s_q_avg = 0, slice_y, bytes_left = 0;
     int median_ener = 0, total_bytes_needed = 0;
 
     int best = s->num_x*s->num_y/5;
@@ -715,6 +715,7 @@ static int calc_slice_sizes(VC2EncContext *s)
         SliceArgs *args = &enc_args[i];
         s->slice_ratings[i] = args;
         bytes_left += s->slice_max_bytes - args->bytes;
+        s_q_avg = (s_q_avg + args->quant_idx)/2;
         median_ener = (median_ener + args->hh_ener)/2;
     }
 
@@ -725,7 +726,7 @@ static int calc_slice_sizes(VC2EncContext *s)
         SliceArgs *h = s->slice_ratings[s->num_x*s->num_y - i - 1];
         int h_step, h_n_idx, h_bits, h_bytes, h_needs;
 
-        if (l_pos <= 0 && bytes_left <= 0)
+        if (!s_q_avg || (l_pos <= 0 && bytes_left <= 0))
             break;
 
         h_step  = ff_log2(FFABS(h->hh_ener - median_ener));
@@ -1257,8 +1258,8 @@ alloc_fail:
 #define VC2ENC_FLAGS (AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM)
 static const AVOption vc2enc_options[] = {
     {"tolerance",     "Max undershoot in percent", offsetof(VC2EncContext, tolerance), AV_OPT_TYPE_DOUBLE, {.dbl = 5.0f}, 0.0f, 45.0f, VC2ENC_FLAGS, "tolerance"},
-    {"slice_width",   "Slice width",  offsetof(VC2EncContext, slice_width), AV_OPT_TYPE_INT, {.i64 = 64}, 32, 1024, VC2ENC_FLAGS, "slice_width"},
-    {"slice_height",  "Slice height", offsetof(VC2EncContext, slice_height), AV_OPT_TYPE_INT, {.i64 = 32}, 8, 1024, VC2ENC_FLAGS, "slice_height"},
+    {"slice_width",   "Slice width",  offsetof(VC2EncContext, slice_width), AV_OPT_TYPE_INT, {.i64 = 32}, 32, 1024, VC2ENC_FLAGS, "slice_width"},
+    {"slice_height",  "Slice height", offsetof(VC2EncContext, slice_height), AV_OPT_TYPE_INT, {.i64 = 16}, 8, 1024, VC2ENC_FLAGS, "slice_height"},
     {"wavelet_depth", "Transform depth", offsetof(VC2EncContext, wavelet_depth), AV_OPT_TYPE_INT, {.i64 = 4}, 1, 5, VC2ENC_FLAGS, "wavelet_depth"},
     {"wavelet_type",  "Transform type",  offsetof(VC2EncContext, wavelet_idx), AV_OPT_TYPE_INT, {.i64 = VC2_TRANSFORM_9_7}, 0, VC2_TRANSFORMS_NB, VC2ENC_FLAGS, "wavelet_idx"},
         {"9_7",          "Deslauriers-Dubuc (9,7)", 0, AV_OPT_TYPE_CONST, {.i64 = VC2_TRANSFORM_9_7},    INT_MIN, INT_MAX, VC2ENC_FLAGS, "wavelet_idx"},
-- 
2.8.0.rc3