Enhancements and typo

[miketerada]

There are a few values that can be added for completeness.

1. SegmentTemplate - can be part of AdaptationSet and should be added to the struct.

    <AdaptationSet mimeType="video/mp4" segmentAlignment="true" startWithSAP="1" bitstreamSwitching="false" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
      <SegmentTemplate timescale="90000" duration="180180" startNumber="1"/>

2. Duration - should be added to SegmentTemplate.

Duration. *string `xml:"duration,attr"`

<SegmentTemplate timescale="44100" media="aac_$Number%09d$.mp4" initialization="aacinit.mp4" duration="88288" startNumber="1"/>

3. AudioChannelConfiguration - should be added to Representation.

AudioChannelConfiguration *AudioChannelConfiguration `xml:"AudioChannelConfiguration,omitempty"`

type AudioChannelConfiguration struct {
    SchemeIDURI *string `xml:"schemeIdUri,attr"`
    Value       *string `xml:"value,attr,omitempty"`
}

<Representation id="6" bandwidth="192000" audioSamplingRate="48000" codecs="ec-3">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="6"/>
</Representation>