Issue #1820 - Part 1 : Add an extraction function to parse the RFC-6381 VP9 codec string.

dom/media/VideoUtils.cpp

@@ -223,13 +223,186 @@ already_AddRefed<SharedThreadPool> GetMediaThreadPool(MediaThreadType aType)
   return pool.forget();
 }
 
+bool
+ExtractVPXCodecDetails(const nsAString& aCodec,
+                       uint8_t& aProfile,
+                       uint8_t& aLevel,
+                       uint8_t& aBitDepth)
+{
+  uint8_t dummyChromaSubsampling = 1;
+  VideoColorSpace dummyColorspace;
+  return ExtractVPXCodecDetails(aCodec,
+                                aProfile,
+                                aLevel,
+                                aBitDepth,
+                                dummyChromaSubsampling,
+                                dummyColorspace);
+}
+
+bool ExtractVPXCodecDetails(const nsAString& aCodec,
+                            uint8_t& aProfile,
+                            uint8_t& aLevel,
+                            uint8_t& aBitDepth,
+                            uint8_t& aChromaSubsampling,
+                            VideoColorSpace& aColorSpace)
+{
+  nsTArray<nsString> fieldsArr;
+
+  // Assign default value.
+  aChromaSubsampling = 1;
+  
+  nsCharSeparatedTokenizer tokenizer(aCodec, '.');
+  while (tokenizer.hasMoreTokens()) {
+    const nsSubstring& token = tokenizer.nextToken();
+    fieldsArr.AppendElement(token);
+  }
+  auto fourCC = fieldsArr[0];
+
+  if (!fourCC.EqualsLiteral("vp09") && !fourCC.EqualsLiteral("vp08")) {
+    // Invalid 4CC
+    return false;
+  }
+  uint8_t *fields[] = { &aProfile, &aLevel, &aBitDepth, &aChromaSubsampling,
+                        &aColorSpace.mPrimaryId, &aColorSpace.mTransferId,
+                        &aColorSpace.mMatrixId, &aColorSpace.mRangeId };
+  int fieldsCount = 0;
+  nsresult rv;
+  for (int fieldsItr = 1; fieldsItr < fieldsArr.Length(); ++fieldsItr, ++fieldsCount) {
+    if (fieldsCount > 7) {
+      // No more than 8 fields are expected.
+      return false;
+    }
+    *(fields[fieldsCount]) =
+      static_cast<uint8_t>(fieldsArr[fieldsItr].ToInteger(&rv));
+    // We got invalid field value, parsing error.
+    NS_ENSURE_SUCCESS(rv, false);
+  }
+  // Mandatory Fields
+  // <sample entry 4CC>.<profile>.<level>.<bitDepth>.
+  // Optional Fields
+  // <chromaSubsampling>.<colourPrimaries>.<transferCharacteristics>.
+  // <matrixCoefficients>.<videoFullRangeFlag>
+  // First three fields are mandatory(we have parsed 4CC).
+  if (fieldsCount < 3) {
+    // Invalid number of fields.
+    return false;
+  }
+  // Start to validate the parsing value.
+
+  // profile should be 0,1,2 or 3.
+  // See https://www.webmproject.org/vp9/profiles/
+  // We don't support more than profile 2
+  if (aProfile > 2) {
+    // Invalid profile.
+    return false;
+  }
+
+ // level, See https://www.webmproject.org/vp9/mp4/#semantics_1
+  switch (aLevel) {
+    case 10:
+    case 11:
+    case 20:
+    case 21:
+    case 30:
+    case 31:
+    case 40:
+    case 41:
+    case 50:
+    case 51:
+    case 52:
+    case 60:
+    case 61:
+    case 62:
+      break;
+    default:
+      // Invalid level.
+      return false;
+  }
+
+  if (aBitDepth != 8 && aBitDepth != 10 && aBitDepth != 12) {
+    // Invalid bitDepth:
+    return false;
+  }
+
+  if (fieldsCount == 3) {
+    // No more options.
+    return true;
+  }
+
+  // chromaSubsampling should be 0,1,2,3...4~7 are reserved.
+  if (aChromaSubsampling > 3) {
+    return false;
+  }
+
+  if (fieldsCount == 4) {
+    // No more options.
+    return true;
+  }
+
+  // It is an integer that is defined by the "Colour primaries"
+  // section of ISO/IEC 23001-8:2016 Table 2.
+  // We treat reserved value as false case.
+  const auto& primaryId = aColorSpace.mPrimaryId;
+  if (primaryId == 0 || primaryId == 3 || primaryId > 22) {
+    // reserved value.
+    return false;
+  }
+  if (primaryId > 12 && primaryId < 22) {
+    // 13~21 are reserved values.
+    return false;
+  }
+
+  if (fieldsCount == 5) {
+    // No more options.
+    return true;
+  }
+
+  // It is an integer that is defined by the
+  // "Transfer characteristics" section of ISO/IEC 23001-8:2016 Table 3.
+  // We treat reserved value as false case.
+  const auto& transferId = aColorSpace.mTransferId;
+  if (transferId == 0 || transferId == 3 || transferId > 18) {
+    // reserved value.
+    return false;
+  }
+
+  if (fieldsCount == 6) {
+    // No more options.
+    return true;
+  }
+
+  // It is an integer that is defined by the
+  // "Matrix coefficients" section of ISO/IEC 23001-8:2016 Table 4.
+  // We treat reserved value as false case.
+  const auto& matrixId = aColorSpace.mMatrixId;
+  if (matrixId == 3 || matrixId > 11) {
+    return false;
+  }
+
+  // If matrixCoefficients is 0 (RGB), then chroma subsampling MUST be 3 (4:4:4).
+  if (matrixId == 0 && aChromaSubsampling != 3) {
+    return false;
+  }
+
+  if (fieldsCount == 7) {
+    // No more options.
+    return true;
+  }
+
+  // videoFullRangeFlag indicates the black level and range of the luma and
+  // chroma signals. 0 = legal range (e.g. 16-235 for 8 bit sample depth);
+  // 1 = full range (e.g. 0-255 for 8-bit sample depth).
+  const auto& rangeId = aColorSpace.mRangeId;
+  return rangeId <= 1;
+}
+
 bool
 ExtractH264CodecDetails(const nsAString& aCodec,
                         int16_t& aProfile,
                         int16_t& aLevel)
 {
   // H.264 codecs parameters have a type defined as avcN.PPCCLL, where
-  // N = avc type. avc3 is avcc with SPS & PPS implicit (within stream)
+  // N = avc type. avc3 is avcc with SPS & PPS implicit (within stream)
   // PP = profile_idc, CC = constraint_set flags, LL = level_idc.
   // We ignore the constraint_set flags, as it's not clear from any
   // documentation what constraints the platform decoders support.

dom/media/VideoUtils.h

@@ -258,6 +258,34 @@ ExtractH264CodecDetails(const nsAString& aCodecs,
                         int16_t& aProfile,
                         int16_t& aLevel);
 
+struct VideoColorSpace
+{
+  // TODO: Define the value type as strong type enum
+  // to better know the exact meaning corresponding to ISO/IEC 23001-8:2016.
+  // Default value is listed https://www.webmproject.org/vp9/mp4/#optional-fields
+  uint8_t mPrimaryId = 1; // Table 2
+  uint8_t mTransferId = 1; // Table 3
+  uint8_t mMatrixId = 1; // Table 4
+  uint8_t mRangeId = 0;
+};
+
+// Extracts the VPX codecs parameter string.
+// See https://www.webmproject.org/vp9/mp4/#codecs-parameter-string
+// for more details.
+// Returns false on failure.
+bool
+ExtractVPXCodecDetails(const nsAString& aCodec,
+                       uint8_t& aProfile,
+                       uint8_t& aLevel,
+                       uint8_t& aBitDepth);
+bool
+ExtractVPXCodecDetails(const nsAString& aCodec,
+                       uint8_t& aProfile,
+                       uint8_t& aLevel,
+                       uint8_t& aBitDepth,
+                       uint8_t& aChromaSubsampling,
+                       VideoColorSpace& aColorSpace);
+
 // Use a cryptographic quality PRNG to generate raw random bytes
 // and convert that to a base64 string.
 nsresult