[FFmpeg-devel] [PATCH 1/3] dnxhddec: better support for 4:4:4

[Christophe Gisquet]

Profiles 1256 & 1270 (currently) signal at the frame header and MB
levels the colorspace used, either RGB or YUV. While a MB-level
varying colorspace is not supported, whether it is constant can be
tracked so as to determine the exact colorspace.

It is not tested against a true RGB sequence, though.
---
 libavcodec/dnxhddec.c | 82 ++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 62 insertions(+), 20 deletions(-)

diff --git a/libavcodec/dnxhddec.c b/libavcodec/dnxhddec.c
index fec9aac..52fd334 100644
--- a/libavcodec/dnxhddec.c
+++ b/libavcodec/dnxhddec.c
@@ -43,6 +43,8 @@ typedef struct RowContext {
     int last_dc[3];
     int last_qscale;
     int errors;
+    /** -1:not set yet  0:off=RGB  1:on=YUV  2:variable */
+    int format;
 } RowContext;
 
 typedef struct DNXHDContext {
@@ -202,6 +204,18 @@ static int dnxhd_decode_header(DNXHDContext *ctx, AVFrame *frame,
     }
     ctx->avctx->bits_per_raw_sample = ctx->bit_depth;
 
+    cid = AV_RB32(buf + 0x28);
+    if ((ret = dnxhd_init_vlc(ctx, cid)) < 0)
+        return ret;
+    if (ctx->mbaff && ctx->cid_table->cid != 1260)
+        av_log(ctx->avctx, AV_LOG_WARNING,
+               "Adaptive MB interlace flag in an unsupported profile.\n");
+
+    ctx->act = buf[0x2C] & 7;
+    if (ctx->act && ctx->cid_table->cid != 1256 && ctx->cid_table->cid != 1270)
+        av_log(ctx->avctx, AV_LOG_WARNING,
+               "Adaptive color transform in an unsupported profile.\n");
+
     ctx->is_444 = (buf[0x2C] >> 6) & 1;
     if (ctx->is_444) {
         if (ctx->bit_depth == 8) {
@@ -209,10 +223,12 @@ static int dnxhd_decode_header(DNXHDContext *ctx, AVFrame *frame,
             return AVERROR_INVALIDDATA;
         } else if (ctx->bit_depth == 10) {
             ctx->decode_dct_block = dnxhd_decode_dct_block_10_444;
-            ctx->pix_fmt = AV_PIX_FMT_YUV444P10;
+            ctx->pix_fmt = ctx->act ? AV_PIX_FMT_YUV444P10
+                                    : AV_PIX_FMT_GBRP10;
         } else {
             ctx->decode_dct_block = dnxhd_decode_dct_block_12_444;
-            ctx->pix_fmt = AV_PIX_FMT_YUV444P12;
+            ctx->pix_fmt = ctx->act ? AV_PIX_FMT_YUV444P12
+                                    : AV_PIX_FMT_GBRP12;
         }
     } else if (ctx->bit_depth == 12) {
         ctx->decode_dct_block = dnxhd_decode_dct_block_12;
@@ -231,19 +247,6 @@ static int dnxhd_decode_header(DNXHDContext *ctx, AVFrame *frame,
                           ff_zigzag_direct);
     }
 
-    cid = AV_RB32(buf + 0x28);
-
-    if ((ret = dnxhd_init_vlc(ctx, cid)) < 0)
-        return ret;
-    if (ctx->mbaff && ctx->cid_table->cid != 1260)
-        av_log(ctx->avctx, AV_LOG_WARNING,
-               "Adaptive MB interlace flag in an unsupported profile.\n");
-
-    ctx->act = buf[0x2C] & 7;
-    if (ctx->act && ctx->cid_table->cid != 1256 && ctx->cid_table->cid != 1270)
-        av_log(ctx->avctx, AV_LOG_WARNING,
-               "Adaptive color transform in an unsupported profile.\n");
-
     // make sure profile size constraints are respected
     // DNx100 allows 1920->1440 and 1280->960 subsampling
     if (ctx->width != ctx->cid_table->width &&
@@ -462,11 +465,17 @@ static int dnxhd_decode_macroblock(const DNXHDContext *ctx, RowContext *row,
     }
     act = get_bits1(&row->gb);
     if (act) {
-        static int warned = 0;
-        if (!warned) {
-            warned = 1;
-            av_log(ctx->avctx, AV_LOG_ERROR,
-                   "Unsupported adaptive color transform, patch welcome.\n");
+        if (!ctx->act) {
+            static int act_warned = 0;
+            if (!act_warned) {
+                act_warned = 1;
+                av_log(ctx->avctx, AV_LOG_ERROR,
+                       "ACT flag set, in violation of frame header.\n");
+            }
+        } else if (row->format == -1) {
+            row->format = act;
+        } else if (row->format != act) {
+            row->format = 2; // Variable
         }
     }
 
@@ -577,6 +586,9 @@ static int dnxhd_decode_frame(AVCodecContext *avctx, void *data,
 
     ff_dlog(avctx, "frame size %d\n", buf_size);
 
+    for (i = 0; i < avctx->thread_count; i++)
+        ctx->rows[i].format = -1;
+
 decode_coding_unit:
     if ((ret = dnxhd_decode_header(ctx, picture, buf, buf_size, first_field)) < 0)
         return ret;
@@ -622,6 +634,36 @@ decode_coding_unit:
         ctx->rows[i].errors = 0;
     }
 
+    if (ctx->act) {
+        static int act_warned = 0;
+        int format = ctx->rows[0].format;
+        for (i = 1; i < avctx->thread_count; i++) {
+            if (ctx->rows[i].format != format &&
+                ctx->rows[i].format != -1 /* not run */) {
+                format = 2;
+                break;
+            }
+        }
+        switch (format) {
+        case -1:
+        case 2:
+            if (!act_warned) {
+                act_warned = 1;
+                av_log(ctx->avctx, AV_LOG_ERROR,
+                       "Unsupported: variable ACT flag.\n");
+            }
+            break;
+        case 0:
+            ctx->pix_fmt = ctx->bit_depth==10
+                         ? AV_PIX_FMT_GBRP10 : AV_PIX_FMT_GBRP12;
+            break;
+        case 1:
+            ctx->pix_fmt = ctx->bit_depth==10
+                         ? AV_PIX_FMT_YUV444P10 : AV_PIX_FMT_YUV444P12;
+            break;
+        }
+    }
+    avctx->pix_fmt = ctx->pix_fmt;
     if (ret) {
         av_log(ctx->avctx, AV_LOG_ERROR, "%d lines with errors\n", ret);
         return AVERROR_INVALIDDATA;
-- 
2.5.2