Audio Format; Dsd Over Pcm (Dop) - XMOS xCORE-200 Multi-channel Audio board Design Manual

USB Audio Design Guide
The following defines affect full-speed operation:

4.5.3 Audio Format

The design supports two audio formats, PCM and Direct Stream Digital (DSD). A
DSD capable DAC is required for the latter.
The USB Audio Raw Data format is used to indicate DSD data (2.3.1.7.5 of USB
Device Class Definition for Audio Data Formats
in an alternative setting is termed Native DSD
The following defines affect both full-speed and high-speed operation:
STREAM_FORMAT_OUTPUT_1_DATAFORMAT
STREAM_FORMAT_OUTPUT_2_DATAFORMAT
STREAM_FORMAT_OUTPUT_3_DATAFORMAT
The following options are supported:
UAC_FORMAT_TYPEI_RAW_DATA
UAC_FORMAT_TYPEI_PCM
Currently DSD is only supported on the output/playback stream
4 byte slot size with a 32 bit resolution is required for RAW/DSD format
Native DSD requires driver support and is available in the Thesycon Windows driver
via ASIO.

4.6 DSD over PCM (DoP)

While Native DSD support is available in Windows though a driver, OSX incorporates
a USB driver that only supports PCM, this is also true of the central audio engine,
CoreAudio. It is therefore not possible to use the scheme defined above using the
built in driver support of OSX.
Since the Apple OS only allows a PCM path a method of transporting DSD audio
data over PCM frames has been developed. This data can then be sent via the
native USB Audio support.
The XMOS USB Audio design(s) implement the method described in DoP Open
Standard 1.1
25
http://www.usb.org/developers/devclass_docs/Audio2.0_final.zip
26
http://dsd-guide.com/sites/default/files/white-papers/DoP_openStandard_1v1.pdf
XM0088546.1
FS_STREAM_FORMAT_OUTPUT_1_RESOLUTION_BITS
FS_STREAM_FORMAT_OUTPUT_2_RESOLUTION_BITS
FS_STREAM_FORMAT_OUTPUT_3_RESOLUTION_BITS
26
25
). This use of a RAW/DSD format
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