Explicitly specify color space enum indices

This CL changes the color space enum indices to have the same
values as specified in H264. The reason for this is to simplify
a coming transmission protocol for color space information.

Bug: webrtc:8651
Change-Id: I16fccae137f75d96ed925ed1421b111ec29ae7c9
Reviewed-on: https://webrtc-review.googlesource.com/c/111245
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Emircan Uysaler <emircan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25697}

api/video/color_space.h

@@ -11,77 +11,93 @@
 #ifndef API_VIDEO_COLOR_SPACE_H_
 #define API_VIDEO_COLOR_SPACE_H_
 
+#include <stdint.h>
+
 namespace webrtc {
 
-// Used to represent a color space for the purpose of color conversion. This
-// class only represents color information that can be transferred through the
-// bitstream of WebRTC's internal supported codecs:
+// This class represents color information as specified in T-REC H.273,
+// available from https://www.itu.int/rec/T-REC-H.273.
+//
+// WebRTC's supported codecs:
 // - VP9 supports color profiles, see VP9 Bitstream & Decoding Process
 // Specification Version 0.6 Section 7.2.2 "Color config semantics" available
 // from https://www.webmproject.org.
-// TODO(emircan): Extract these values from decode and add to the existing ones.
 // - VP8 only supports BT.601, see
 // https://tools.ietf.org/html/rfc6386#section-9.2
-// - H264 supports different color primaries, transfer characteristics, matrix
-// coefficients and range. See T-REC-H.264 E.2.1, "VUI parameters semantics",
-// available from https://www.itu.int/rec/T-REC-H.264.
+// - H264 uses the exact same representation as T-REC H.273. See T-REC-H.264
+// E.2.1, "VUI parameters semantics", available from
+// https://www.itu.int/rec/T-REC-H.264.
+
 class ColorSpace {
  public:
-  enum class PrimaryID {
-    kInvalid,
-    kBT709,
-    kBT470M,
-    kBT470BG,
-    kSMPTE170M,  // Identical to BT601
-    kSMPTE240M,
-    kFILM,
-    kBT2020,
-    kSMPTEST428,
-    kSMPTEST431,
-    kSMPTEST432,
-    kJEDECP22,
+  enum class PrimaryID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 2.
+    kInvalid = 0,
+    kBT709 = 1,
+    kUNSPECIFIED = 2,
+    kBT470M = 4,
+    kBT470BG = 5,
+    kSMPTE170M = 6,  // Identical to BT601
+    kSMPTE240M = 7,
+    kFILM = 8,
+    kBT2020 = 9,
+    kSMPTEST428 = 10,
+    kSMPTEST431 = 11,
+    kSMPTEST432 = 12,
+    kJEDECP22 = 22,  // Identical to EBU3213-E
   };
 
-  enum class TransferID {
-    kInvalid,
-    kBT709,
-    kGAMMA22,
-    kGAMMA28,
-    kSMPTE170M,
-    kSMPTE240M,
-    kLINEAR,
-    kLOG,
-    kLOG_SQRT,
-    kIEC61966_2_4,
-    kBT1361_ECG,
-    kIEC61966_2_1,
-    kBT2020_10,
-    kBT2020_12,
-    kSMPTEST2084,
-    kSMPTEST428,
-    kARIB_STD_B67,
+  enum class TransferID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 3.
+    kInvalid = 0,
+    kBT709 = 1,
+    kUNSPECIFIED = 2,
+    kGAMMA22 = 4,
+    kGAMMA28 = 5,
+    kSMPTE170M = 6,
+    kSMPTE240M = 7,
+    kLINEAR = 8,
+    kLOG = 9,
+    kLOG_SQRT = 10,
+    kIEC61966_2_4 = 11,
+    kBT1361_ECG = 12,
+    kIEC61966_2_1 = 13,
+    kBT2020_10 = 14,
+    kBT2020_12 = 15,
+    kSMPTEST2084 = 16,
+    kSMPTEST428 = 17,
+    kARIB_STD_B67 = 18,
   };
 
-  enum class MatrixID {
-    kInvalid,
-    kRGB,
-    kBT709,
-    kFCC,
-    kBT470BG,
-    kSMPTE170M,
-    kSMPTE240M,
-    kYCOCG,
-    kBT2020_NCL,
-    kBT2020_CL,
-    kSMPTE2085,
+  enum class MatrixID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 4.
+    kRGB = 0,
+    kBT709 = 1,
+    kUNSPECIFIED = 2,
+    kFCC = 4,
+    kBT470BG = 5,
+    kSMPTE170M = 6,
+    kSMPTE240M = 7,
+    kYCOCG = 8,
+    kBT2020_NCL = 9,
+    kBT2020_CL = 10,
+    kSMPTE2085 = 11,
+    kCDNCLS = 12,
+    kCDCLS = 13,
+    kBT2100_ICTCP = 14,
+    kInvalid = 255
   };
 
   enum class RangeID {
-    kInvalid,
+    // The indices are equal to the values specified at
+    // https://www.webmproject.org/docs/container/#colour for the element Range.
+    kInvalid = 0,
     // Limited Rec. 709 color range with RGB values ranging from 16 to 235.
-    kLimited,
+    kLimited = 1,
     // Full RGB color range with RGB valees from 0 to 255.
-    kFull,
+    kFull = 2,
+    // Range is defined by MatrixCoefficients/TransferCharacteristics.
+    kDerived = 3
   };
 
   ColorSpace();