ADSP-214xx SHARC Processor Hardware Reference C-13
Audio Frame Formats
After the audio sample word, there are four final time slots which carry:
1. Validity bit (time slot 28). The validity bit is logic 0 if the audio
sample word is suitable for conversion to an analog audio signal,
and logic 1 if it is not. This bit is set if the
CHST_BUF_ENABLE bit
and the VALIDITY_A (VALIDITY_B for channel 2) bit is set in the
SPDIF_TX_CTL register. This bit is also set if the corresponding bit
given with the sample is set.
2. User data bit (time slot 29). This bit carries user-specified infor-
mation that may be used in any way. This bit is set if the
corresponding bit given with the left/right sample is set.
3. Channel status bit (time slot 30). The channel status for each
audio signal carries information associated with that audio signal,
making it possible for different channel status data to be carried in
the two subframes of the digital audio signal. Examples of informa-
tion to be carried in the channel status are: length of audio sample
Figure C-5. Subframe Format
PREAMBLE
LSB
MSB
24-BIT AUDIO WORD
VALIDITY
USER
CHANNEL
PAR IT Y
0 3 42728 29 30 31
DATA
STATUS
PREAMBLE
LSB
MSB
20-BIT AUDIO WORD
VALIDITY
USER
CHANNEL
PAR IT Y
0 3 42728 29 30 31
DATA
STATUS
7 8
AUXILIARY
SAMPLE
BITS
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