Add frameRate and codecs information on video tracks

[avelad]

For get the frameRate, only it's necessary read the value parametrer on video representation node.

Two examples:

1. --> frameRate="30"

<Representation id="video=2127105" bandwidth="2127105" width="1280" height="720" frameRate="30" codecs="avc1.4D401F" scanType="progressive">
<BaseURL>HIO042194_11E_video_2300.mp4</BaseURL>
<SegmentBase timescale="30000" indexRangeExact="true" indexRange="752-1287">
<Initialization range="0-751"/>
</SegmentBase>
</Representation>
<Representation id="video=3311660" bandwidth="3311660" width="1920" height="1080" frameRate="30" codecs="avc1.640028" scanType="progressive">
<BaseURL>HIO042194_11E_video_3400.mp4</BaseURL>
<SegmentBase timescale="30000" indexRangeExact="true" indexRange="757-1292">
<Initialization range="0-756"/>
</SegmentBase>
</Representation>

2. https://storage.googleapis.com/shaka-demo-assets/sintel-widevine/dash.mpd --> frameRate="23,8"

<AdaptationSet id="10" contentType="video" maxWidth="3840" maxHeight="1636" frameRate="1000000/42000" par="40:17">
      <Representation id="10" bandwidth="81054" codecs="vp9" mimeType="video/webm" sar="129:128" width="256" height="110">
....

For get the codecs, only it's necessary read the value parametrer on video/audio representation node.

Example:
1)https://storage.googleapis.com/shaka-demo-assets/sintel/dash.mpd --> codec="mp4a.40.2"

<Representation id="15" bandwidth="132318" codecs="mp4a.40.2" mimeType="audio/mp4" audioSamplingRate="48000">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
        <BaseURL>a-eng-0128k-aac.mp4</BaseURL>
        <SegmentBase indexRange="745-1844" timescale="48000">
          <Initialization range="0-744"/>
        </SegmentBase>
      </Representation>

[joeyparrish]

Thanks, we'll consider this feature request when we start planning v2.1.