Change the video color space default.

media/ffmpeg/ffmpeg_common.cc

Index: media/ffmpeg/ffmpeg_common.cc
diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index cb806c74812aba84ee66885a36f746f161ad0129..ba01afd0d60de6dc09f63289e7665f50bb88cbff 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -431,16 +431,20 @@ void AVStreamToVideoDecoderConfig(
     format = VideoFrame::YV12A;
   }
 
-  config->Initialize(codec,
-                     profile,
-                     format,
-                     (stream->codec->colorspace == AVCOL_SPC_BT709)
-                         ? VideoFrame::COLOR_SPACE_HD_REC709
-                         : VideoFrame::COLOR_SPACE_UNSPECIFIED,
-                     coded_size, visible_rect, natural_size,
-                     stream->codec->extradata, stream->codec->extradata_size,
-                     is_encrypted,
-                     record_stats);
+  // Prefer the color space found by libavcodec if available.
+  VideoFrame::ColorSpace color_space =
+      AVColorSpaceToVideoFrameColorSpace(stream->codec->colorspace);
+  if (color_space == VideoFrame::COLOR_SPACE_UNSPECIFIED) {
+    // Otherwise, assume that SD video is usually Rec.601, and HD is usually
+    // Rec.709.
+    color_space = (natural_size.height() < 720)
+                      ? VideoFrame::COLOR_SPACE_SD_REC601
+                      : VideoFrame::COLOR_SPACE_HD_REC709;
+  }
+
+  config->Initialize(codec, profile, format, color_space, coded_size,
+                     visible_rect, natural_size, stream->codec->extradata,
+                     stream->codec->extradata_size, is_encrypted, record_stats);
 }
 
 void VideoDecoderConfigToAVCodecContext(
@@ -564,6 +568,22 @@ PixelFormat VideoFormatToPixelFormat(VideoFrame::Format video_format) {
   return PIX_FMT_NONE;
 }
 
+VideoFrame::ColorSpace AVColorSpaceToVideoFrameColorSpace(
+    AVColorSpace color_space) {
+  switch (color_space) {
+    case AVCOL_SPC_BT709:
+      return VideoFrame::COLOR_SPACE_HD_REC709;
+    case AVCOL_SPC_SMPTE170M:
+    case AVCOL_SPC_BT470BG:
+      return VideoFrame::COLOR_SPACE_SD_REC601;
+    case AVCOL_SPC_UNSPECIFIED:
+      break;
+    default:
+      DVLOG(1) << "Unknown AVColorSpace: " << color_space;
+  }
+  return VideoFrame::COLOR_SPACE_UNSPECIFIED;
+}
+
 bool FFmpegUTCDateToTime(const char* date_utc, base::Time* out) {
   DCHECK(date_utc);
   DCHECK(out);