Bug 1411681 - Cherrypick 6728003bcf5657da8f9ed52ad84f46c1197ce54b from upstream webrtc.org; r=pehrsons

Differential Revision: https://phabricator.services.mozilla.com/D12417

--HG--
extra : moz-landing-system : lando

media/webrtc/trunk/webrtc/common_video/h264/sps_parser.cc

@@ -94,23 +94,31 @@ rtc::Optional<SpsParser::SpsState> SpsParser::ParseSpsUpToVui(
     uint32_t seq_scaling_matrix_present_flag;
     RETURN_EMPTY_ON_FAIL(buffer->ReadBits(&seq_scaling_matrix_present_flag, 1));
     if (seq_scaling_matrix_present_flag) {
-      // seq_scaling_list_present_flags. Either 8 or 12, depending on
-      // chroma_format_idc.
-      uint32_t seq_scaling_list_present_flags;
-      if (chroma_format_idc != 3) {
+      // Process the scaling lists just enough to be able to properly
+      // skip over them, so we can still read the resolution on streams
+      // where this is included.
+      int scaling_list_count = (chroma_format_idc == 3 ? 12 : 8);
+      for (int i = 0; i < scaling_list_count; ++i) {
+        // seq_scaling_list_present_flag[i]  : u(1)
+        uint32_t seq_scaling_list_present_flags;
         RETURN_EMPTY_ON_FAIL(
-            buffer->ReadBits(&seq_scaling_list_present_flags, 8));
-      } else {
-        RETURN_EMPTY_ON_FAIL(
-            buffer->ReadBits(&seq_scaling_list_present_flags, 12));
-      }
-      // We don't support reading the sequence scaling list, and we don't really
-      // see/use them in practice, so we'll just reject the full sps if we see
-      // any provided.
-      if (seq_scaling_list_present_flags > 0) {
-        RTC_LOG(LS_WARNING)
-            << "SPS contains scaling lists, which are unsupported.";
-        return OptionalSps();
+            buffer->ReadBits(&seq_scaling_list_present_flags, 1));
+        if (seq_scaling_list_present_flags != 0) {
+          int last_scale = 8;
+          int next_scale = 8;
+          int size_of_scaling_list = i < 6 ? 16 : 64;
+          for (int j = 0; j < size_of_scaling_list; j++) {
+            if (next_scale != 0) {
+              int32_t delta_scale;
+              // delta_scale: se(v)
+              RETURN_EMPTY_ON_FAIL(
+                  buffer->ReadSignedExponentialGolomb(&delta_scale));
+              next_scale = (last_scale + delta_scale + 256) % 256;
+            }
+            if (next_scale != 0)
+              last_scale = next_scale;
+          }
+        }
       }
     }
   }

media/webrtc/trunk/webrtc/common_video/h264/sps_parser_unittest.cc

@@ -171,4 +171,17 @@ TEST_F(H264SpsParserTest, TestSyntheticSPSWeirdResolution) {
   EXPECT_EQ(2u, sps_->id);
 }
 
+TEST_F(H264SpsParserTest, TestSampleSPSWithScalingLists) {
+  // SPS from a 1920x1080 video. Contains scaling lists (and veritcal cropping).
+  const uint8_t buffer[] = {0x64, 0x00, 0x2a, 0xad, 0x84, 0x01, 0x0c, 0x20,
+                            0x08, 0x61, 0x00, 0x43, 0x08, 0x02, 0x18, 0x40,
+                            0x10, 0xc2, 0x00, 0x84, 0x3b, 0x50, 0x3c, 0x01,
+                            0x13, 0xf2, 0xcd, 0xc0, 0x40, 0x40, 0x50, 0x00,
+                            0x00, 0x00, 0x10, 0x00, 0x00, 0x01, 0xe8, 0x40};
+  EXPECT_TRUE(
+      static_cast<bool>(sps_ = SpsParser::ParseSps(buffer, arraysize(buffer))));
+  EXPECT_EQ(1920u, sps_->width);
+  EXPECT_EQ(1080u, sps_->height);
+}
+
 }  // namespace webrtc