webm2pes: Split super frames and packetize large frames.

- PES depacketizers don't want anything but simple encoded frames.
- Large in this case means frame size + size of PES header
  is > UINT16_MAX.

Change-Id: Ifb76caaa97a0dcf3600228a0cbc4d4f2533027a7

webm2pes.h

@@ -161,6 +161,8 @@ struct PesHeader {
 // https://en.wikipedia.org/wiki/MPEG_transport_stream
 class Webm2Pes {
  public:
+  enum VideoCodec { VP8, VP9 };
+
   Webm2Pes(const std::string& input_file, const std::string& output_file)
       : input_file_name_(input_file), output_file_name_(output_file) {}
 
@@ -196,6 +198,9 @@ class Webm2Pes {
   // Video track num in the WebM file.
   int video_track_num_ = 0;
 
+  // Video codec reported by CodecName from Video TrackEntry.
+  VideoCodec codec_;
+
   // Input timecode scale.
   std::int64_t timecode_scale_ = 1000000;
 };