HDMI 1.4/2.0 TX Subsystem
37
PG235 October 4, 2017
Chapter
3:
Designing with the Subsystem
example, if you intend to send out 8 channel audio, then you must set Audio Channel
number to 8 in HDMI 1.4/2.0 Transmitter Subsystem driver. Then, the corresponding audio
data must be prepared and sent to HDMI 1.4/2.0 Transmitter Subsystem in the hardware, as
described in
IMPORTANT:
When multiple channel audio is enabled in the system, ensure that the audio data is
properly sent to their perspective channel allocation. Unused channels must be packed with zero (i.e.
Mute) to avoid audio channel swapping, which means audio data may appear in unexpected channel
locations.
In HDMI TX Subsystem, L-PCM (IEC 60958, Packet Type 0x02) and HBR (Packet Type 0x09)
are handled by the hardware. An API function is available that allows for the setting of the
audio format, and the hardware packs the audio based on the Audio Format selected.
void XV_HdmiTxSs_SetAudioFormat(XV_HdmiTxSs *InstancePtr, u8 format);
where:
InstancePtr is a pointer to XV_HdmiTxSs instance
format is a selector of Audio Format
- 1:HBR
- 0:L-PCM
Note:
The L-PCM (Packet Type 0x02) allows you to pack up to 24 bits of audio from the Audio Data
Stream. The HBR (Packet Type 0x09) allows you to pack up to 16 bits of audio from the Audio Data
Stream. The data is taken from MSB (bit 27:12). Compressed Audio (IEC 61937) can also be sent the
same as L-PCM data (IEC60958). However, it is your responsibility to compress the audio data and
uncompress the data audio with your custom logic.
IMPORTANT:
L-PCM (IEC60958) Audio is the only Audio format tested on board by Xilinx only in
Example Design.
Video Input Stream Interface
The AXI4-Stream video interface supports dual or quad pixels per clock with 8 bits, 10 bits,
12 bits and 16 bits per component for RGB, YUV444, and YUV420 color spaces. The color
depth in YUV422 color space is always 12-bits per pixel.
When the parameter,
Max Bits Per Component
, is set to 16,
shows the data
format for quad pixels per clock to be fully compliant with the AXI4-Stream video protocol.
A data format for a fully compliant AXI4-Stream video protocol dual pixels per clock is
illustrated in