Add channelcount information on audio tracks

[avelad]

For get the channels count, only it's necessary read the value parametrer on AudioChannelConfiguration node.

Two examples:

1. 2 channels

<AdaptationSet id="11" contentType="audio" lang="en" subsegmentAlignment="true">
      <Representation id="14" 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>
    </AdaptationSet>

2. 6 channels

<AdaptationSet
 mimeType="audio/mp4"
 codecs="dtse"
 lang="en"
 audioSamplingRate="48000"
 startWithSAP="1"
 subsegmentStartsWithSAP="1" >
 <AudioChannelConfiguration
 schemeIdUri="urn:dts:dash:audio_channel_configuration:2012"
 value="6"/>
 <ContentComponent id="100" contentType="audio"/>
 <Representation id="a1" bandwidth="192000">
 <BaseURL>dtse_192_dash.mp4</BaseURL>
 <SegmentBase indexRangeExact="true" indexRange="852-920"/>
 </Representation>
 <Representation id="a2" bandwidth="256000">
 <BaseURL>dtse_256_dash.mp4</BaseURL>
 <SegmentBase indexRangeExact="true" indexRange="853-921"/>
 </Representation>
 <Representation id="a3" bandwidth="384000">
 <BaseURL>dtse_384_dash.mp4</BaseURL>
 <SegmentBase indexRangeExact="true" indexRange="852-920"/>
 </Representation>
 <Representation id="a4" bandwidth="510000">
 <BaseURL>dtse_510_dash.mp4</BaseURL>
 <SegmentBase indexRangeExact="true" indexRange="853-921"/>
 </Representation>
 </AdaptationSet>

We would expect something like this for audio track:
{active: true, bandwidth: 132318, channelcount: 2, hasOutputRestrictions: false, height: null, id: 20, kind: null, language: "en", type: "audio", width: null}

[joeyparrish]

Sounds fairly easy. We'll see if we can fit it into v2.0.0. One change, though: I'd prefer the member to be named "channels" instead of "channelcount". Any objections?

[avelad]

Go!! channels name is perfect

[joeyparrish]

Actually, now that we've looked into it, this is not so clear. The DASH spec has some very confusing text about the meaning of the value attribute, and we can't convince ourselves that this is supposed to be the number of channels. The spec text around this also refers to multiple other spec documents, one of which we don't currently have access to.

Because of all this, I am going to defer this enhancement. We can look again after v2.0.0 is complete. Sorry!