keyAudioTrackName tracks tracks.keyAudioTrackName track enabled mixdownEnabled drc codecs codecs.keyAudioCodecName codec mixdowns mixdowns.keyAudioMixdownName mixdown sampleRates sampleRates.keyAudioSampleRateName sampleRate bitRates bitRates.keyAudioBitrateName bitRate DRCEnabled gain PassThruEnabled PassThruDisabled bitrateEnabled