lavfi/drawutils: improve colorspace support

- Introduce ff_draw_init2, which takes explicit colorspace and range
  args
- Use lavu/csp and lavfi/colorspace for conversion, rather than the
  lavu/colorspace.h macros
- Use the passed-in colorspace when performing RGB->YUV conversions

The upshot of this is:
- Support for YUV spaces other than BT601
- Better rounding for all conversions
- Particular rounding improvements in >8-bit formats, which previously
  used simple left-shifts
- Support for limited-range RGB
- Support for full-range YUV in non-J pixfmts

Due to the rounding improvements, this results in a large number of
minor changes to FATE tests.

Signed-off-by: rcombs <rcombs@rcombs.me>

1 files changed, 22 insertions, 4 deletions

diff --git a/libavfilter/drawutils.h b/libavfilter/drawutils.h
index 396688514e..90df55107a 100644
--- a/libavfilter/drawutils.h
+++ b/libavfilter/drawutils.h
@@ -41,8 +41,10 @@ typedef struct FFDrawContext {
     uint8_t vsub[MAX_PLANES];  /*< vertical subsampling */
     uint8_t hsub_max;
     uint8_t vsub_max;
-    int full_range;
+    enum AVColorRange range;
     unsigned flags;
+    enum AVColorSpace csp;
+    double rgb2yuv[3][3];
 } FFDrawContext;
 
 typedef struct FFDrawColor {
@@ -64,13 +66,29 @@ typedef struct FFDrawColor {
  *
  * Only a limited number of pixel formats are supported, if format is not
  * supported the function will return an error.
- * flags is combination of FF_DRAW_* flags.
- * @return  0 for success, < 0 for error
+ * @param format  pixel format of the frames that will be drawn onto
+ * @param csp     color space of the frames that will be drawn onto,
+ *                defaulting to BT601 or RGB depending on the specified format
+ *                when AVCOL_SPC_UNSPECIFIED is passed.
+ * @param range   sample value range of the frames that will be drawn onto,
+ *                defaulting to TV-range unless using a legacy J format
+ *                when AVCOL_RANGE_UNSPECIFIED is passed.
+ * @param flags   combination of FF_DRAW_* flags.
+ * @return        0 for success, < 0 for error
+ */
+int ff_draw_init2(FFDrawContext *draw, enum AVPixelFormat format, enum AVColorSpace csp,
+                  enum AVColorRange range, unsigned flags);
+
+/*
+ * Legacy wrapper for ff_draw_init2.
  */
 int ff_draw_init(FFDrawContext *draw, enum AVPixelFormat format, unsigned flags);
 
+
+
 /**
- * Prepare a color.
+ * Prepare a color. The rgba value passed is always 8-bit full-range in the RGB space
+ * corresponding to the space set at initialization.
  */
 void ff_draw_color(FFDrawContext *draw, FFDrawColor *color, const uint8_t rgba[4]);