Grass Valley iTX System v.2.6 - Manual (Page 209)

Configuring the audio output for a playout channel
You may select any one of up to 16 groups (numbered 0 to 15) in the source media. See below,
“Track grouping”.
Pass-through option
Selecting Pass sets up iTX to use the audio passthrough option, to produce multiple
PCM stereo outputs from pairs of successive PCM mono tracks. The option relates
to early versions of iTX v2, in which it was not possible to identify the required
tracks by group numbers.
Since the introduction of the channel-grouping functionality, this option is no longer
required. When you want iTX to use channels from different mono tracks for a PCM
stereo output, you should use channel grouping to identify channel pairs.
How iTX determines which source track to use for the output
In selecting which source track to use for an output track, iTX follows a set of rules that take
account of the Audio Mapping configuration. The rules cause iTX to perform a series of checks
in the order given below, until it finds a track that meets the requirements.
In this process, iTX treats multiple tracks with the same group number as a single track – when
it selects a particular group for playout, it uses all the tracks in the group.
1. Tag matching
• iTX first notes whether or not there is a Language tag specified. If there is, it checks
source tracks that are of the same audio type as the output track; when it finds a track
with a tag that matches the one specified, it selects this track for playout.
• If there is no such track, iTX searches compatible source tracks of other audio types. If
it finds a track with the required tag, it selects this track for playout.
• If the output format is PCM stereo and there is only a PCM mono source track with the
required tag, iTX assigns this track to both left and right stereo outputs.
2. Group matching
• If there is no suitably tagged track, iTX notes whether or not there is a group number
specified in the configuration. If there is, it selects the compatible source track with
this number.
• If the output format is PCM stereo and there is only a PCM mono source track with the
required group number, iTX assigns this track to both left and right stereo outputs.
3. Default matching
• If neither tag matching nor group matching can be applied, iTX can apply a default
group to the track. The default group can be specified from the Default column in the
Audio Mapping section.
• If the output format is PCM stereo and there is only a PCM mono source track that is
untagged, iTX assigns this track to both left and right stereo outputs.
• If the Default column is set to Silence, the output from that track will be mute.
4. Use of untagged tracks
• If there is no track that matches the Language or Group configuration entries, iTX
selects the first untagged source track that is of the same audio type as the output
track. If there is no such track, it selects the first compatible untagged track.
March 2015 System Administrator Guide Page 209 of 404