MediaRecorder: use VideoTrackRecorder::GetPreferredCodecId() when available

This CL adds a static method to VTR to query which
one, if any, is the preferred video codec.

A new singleton Lazy Leaky class CodecEnumerator is
added to encapsulate poking the VEA to see which
codecs are supported, and to further query
a) the preferred codec id
b) if a given codec is supported
and wraps the previous CodecIdToVEAProfile()
functionality.

BUG=679946

Review-Url: https://codereview.chromium.org/2624053002
Cr-Commit-Position: refs/heads/master@{#443165}

content/browser/webrtc/webrtc_media_recorder_browsertest.cc

@@ -23,6 +23,7 @@ static struct EncodingParameters {
     {true, "video/webm;codecs=VP8"},
     {true, "video/webm;codecs=VP9"},
     {true, "video/x-matroska;codecs=AVC1"},
+    {false, ""},  // Instructs the platform to choose any accelerated codec.
     {false, "video/webm;codecs=VP8"},
     {false, "video/webm;codecs=VP9"},
     {false, "video/x-matroska;codecs=AVC1"},

content/renderer/media/media_recorder_handler.cc

@@ -42,6 +42,8 @@ media::VideoCodec CodecIdToMediaVideoCodec(VideoTrackRecorder::CodecId id) {
       return media::kCodecVP9;
     case VideoTrackRecorder::CodecId::H264:
       return media::kCodecH264;
+    case VideoTrackRecorder::CodecId::LAST:
+      return media::kUnknownVideoCodec;
   }
   NOTREACHED() << "Unsupported codec";
   return media::kUnknownVideoCodec;
@@ -119,8 +121,7 @@ bool MediaRecorderHandler::initialize(
   UpdateWebRTCMethodCount(WEBKIT_MEDIA_STREAM_RECORDER);
 
   if (!canSupportMimeType(type, codecs)) {
-    DLOG(ERROR) << "Can't support " << type.utf8()
-                << ";codecs=" << codecs.utf8();
+    DLOG(ERROR) << "Unsupported " << type.utf8() << ";codecs=" << codecs.utf8();
     return false;
   }
 
@@ -136,6 +137,11 @@ bool MediaRecorderHandler::initialize(
   else if (codecs_str.find("avc1") != std::string::npos)
     codec_id_ = VideoTrackRecorder::CodecId::H264;
 #endif
+  else
+    codec_id_ = VideoTrackRecorder::GetPreferredCodecId();
+
+  DVLOG_IF(1, codecs_str.empty()) << "Falling back to preferred codec id "
+                                  << static_cast<int>(codec_id_);
 
   media_stream_ = media_stream;
   DCHECK(client);

content/renderer/media/video_track_recorder.cc

@@ -60,60 +60,98 @@ const int kVEADefaultBitratePerPixel = 2;
 // encoders.
 const int kVEAEncoderOutputBufferCount = 4;
 
-static struct {
-  VideoTrackRecorder::CodecId codec_id;
+using CodecId = VideoTrackRecorder::CodecId;
+
+static const struct {
+  CodecId codec_id;
   media::VideoCodecProfile min_profile;
   media::VideoCodecProfile max_profile;
-} const kSupportedVideoCodecIdToProfile[] = {
-    {VideoTrackRecorder::CodecId::VP8,
-     media::VP8PROFILE_MIN,
-     media::VP8PROFILE_MAX},
-    {VideoTrackRecorder::CodecId::VP9,
-     media::VP9PROFILE_MIN,
-     media::VP9PROFILE_MAX},
-    {VideoTrackRecorder::CodecId::H264,
-     media::H264PROFILE_MIN,
-     media::H264PROFILE_MAX}};
-
-// Returns the corresponding codec profile from VEA supported codecs. If no
-// profile is found, returns VIDEO_CODEC_PROFILE_UNKNOWN.
-media::VideoCodecProfile CodecIdToVEAProfile(
-    content::VideoTrackRecorder::CodecId codec) {
-  // See https://crbug.com/616659.
+} kPreferredCodecIdAndVEAProfiles[] = {
+    {CodecId::VP8, media::VP8PROFILE_MIN, media::VP8PROFILE_MAX},
+    {CodecId::VP9, media::VP9PROFILE_MIN, media::VP9PROFILE_MAX},
+    {CodecId::H264, media::H264PROFILE_MIN, media::H264PROFILE_MAX}};
+
+static_assert(arraysize(kPreferredCodecIdAndVEAProfiles) ==
+                  static_cast<int>(CodecId::LAST),
+              "|kPreferredCodecIdAndVEAProfiles| should consider all CodecIds");
+
+// Class to encapsulate the enumeration of CodecIds/VideoCodecProfiles supported
+// by the VEA underlying platform. Provides methods to query the preferred
+// CodecId and to check if a given CodecId is supported.
+class CodecEnumerator {
+ public:
+  CodecEnumerator();
+  ~CodecEnumerator() = default;
+
+  // Returns the first CodecId that has an associated VEA VideoCodecProfile, or
+  // VP8 if none available.
+  CodecId GetPreferredCodecId();
+
+  // Returns the VEA VideoCodedProfile for a given CodecId, if supported, or
+  // VIDEO_CODEC_PROFILE_UNKNOWN otherwise.
+  media::VideoCodecProfile CodecIdToVEAProfile(CodecId codec);
+
+ private:
+  // A map of VEA-supported CodecId-and-VEA-profile pairs.
+  std::map<CodecId, media::VideoCodecProfile> codec_id_to_profile_;
+
+  DISALLOW_COPY_AND_ASSIGN(CodecEnumerator);
+};
+
+static base::LazyInstance<CodecEnumerator>::Leaky g_codec_enumerator =
+    LAZY_INSTANCE_INITIALIZER;
+
+CodecEnumerator::CodecEnumerator() {
 #if defined(OS_CHROMEOS)
-  return media::VIDEO_CODEC_PROFILE_UNKNOWN;
-#endif  // defined(OS_CHROMEOS)
+  // See https://crbug.com/616659.
+  return;
+#endif
 
-// See https://crbug.com/653864.
 #if defined(OS_ANDROID)
-  return media::VIDEO_CODEC_PROFILE_UNKNOWN;
-#endif  // defined(OS_ANDROID)
+  // See https://crbug.com/653864.
+  return;
+#endif
 
   content::RenderThreadImpl* const render_thread_impl =
       content::RenderThreadImpl::current();
   if (!render_thread_impl) {
-    DVLOG(3) << "Couldn't access the render thread";
-    return media::VIDEO_CODEC_PROFILE_UNKNOWN;
+    DVLOG(2) << "Couldn't access the render thread";
+    return;
   }
 
   media::GpuVideoAcceleratorFactories* const gpu_factories =
       render_thread_impl->GetGpuFactories();
   if (!gpu_factories || !gpu_factories->IsGpuVideoAcceleratorEnabled()) {
-    DVLOG(3) << "Couldn't initialize GpuVideoAcceleratorFactories";
-    return media::VIDEO_CODEC_PROFILE_UNKNOWN;
+    DVLOG(2) << "Couldn't initialize GpuVideoAcceleratorFactories";
+    return;
   }
 
-  const media::VideoEncodeAccelerator::SupportedProfiles& vea_profiles =
+  const auto vea_supported_profiles =
       gpu_factories->GetVideoEncodeAcceleratorSupportedProfiles();
-  for (const auto& vea_profile : vea_profiles) {
-    for (const auto& supported_profile : kSupportedVideoCodecIdToProfile) {
-      if (codec == supported_profile.codec_id &&
-          vea_profile.profile >= supported_profile.min_profile &&
-          vea_profile.profile <= supported_profile.max_profile)
-        return vea_profile.profile;
+  for (const auto& supported_profile : vea_supported_profiles) {
+    for (auto& codec_id_and_profile : kPreferredCodecIdAndVEAProfiles) {
+      if (supported_profile.profile >= codec_id_and_profile.min_profile &&
+          supported_profile.profile <= codec_id_and_profile.max_profile) {
+        DVLOG(2) << "Accelerated codec found: "
+                 << media::GetProfileName(supported_profile.profile);
+        codec_id_to_profile_.insert(std::make_pair(
+            codec_id_and_profile.codec_id, supported_profile.profile));
+      }
     }
   }
-  return media::VIDEO_CODEC_PROFILE_UNKNOWN;
+}
+
+CodecId CodecEnumerator::GetPreferredCodecId() {
+  if (codec_id_to_profile_.empty())
+    return CodecId::VP8;
+  return codec_id_to_profile_.begin()->first;
+}
+
+media::VideoCodecProfile CodecEnumerator::CodecIdToVEAProfile(CodecId codec) {
+  const auto profile = codec_id_to_profile_.find(codec);
+  return profile == codec_id_to_profile_.end()
+             ? media::VIDEO_CODEC_PROFILE_UNKNOWN
+             : profile->second;
 }
 
 }  // anonymous namespace
@@ -1075,6 +1113,11 @@ void H264Encoder::ConfigureEncoderOnEncodingTaskRunner(const gfx::Size& size) {
 
 }  // anonymous namespace
 
+// static
+VideoTrackRecorder::CodecId VideoTrackRecorder::GetPreferredCodecId() {
+  return g_codec_enumerator.Get().GetPreferredCodecId();
+}
+
 VideoTrackRecorder::VideoTrackRecorder(
     CodecId codec,
     const blink::WebMediaStreamTrack& track,
@@ -1143,7 +1186,8 @@ void VideoTrackRecorder::InitializeEncoder(
   MediaStreamVideoSink::DisconnectFromTrack();
 
   const gfx::Size& input_size = frame->visible_rect().size();
-  const auto& vea_supported_profile = CodecIdToVEAProfile(codec);
+  const auto& vea_supported_profile =
+      g_codec_enumerator.Get().CodecIdToVEAProfile(codec);
   if (vea_supported_profile != media::VIDEO_CODEC_PROFILE_UNKNOWN &&
       input_size.width() >= kVEAEncoderMinResolutionWidth &&
       input_size.height() >= kVEAEncoderMinResolutionHeight) {

content/renderer/media/video_track_recorder.h

@@ -37,10 +37,12 @@ namespace content {
 class CONTENT_EXPORT VideoTrackRecorder
     : NON_EXPORTED_BASE(public MediaStreamVideoSink) {
  public:
+  // Do not change the order of codecs; add new ones right before LAST.
   enum class CodecId {
     VP8,
     VP9,
     H264,
+    LAST
   };
   class Encoder;
 
@@ -50,6 +52,8 @@ class CONTENT_EXPORT VideoTrackRecorder
                           base::TimeTicks capture_timestamp,
                           bool is_key_frame)>;
 
+  static CodecId GetPreferredCodecId();
+
   VideoTrackRecorder(CodecId codec,
                      const blink::WebMediaStreamTrack& track,
                      const OnEncodedVideoCB& on_encoded_video_cb,