Andrej Falout wrote:
On Wed, Oct 15, 2014 at 3:43 AM, Pierre-Louis Bossart wrote:
On 10/13/14, 7:49 PM, Andrej Falout wrote:
What are you basing your assessment that "HDMI controllers typically don't support DSD in the PC space"? I looked, but could not find any evidence for this.
I am basing my judgement on first-hand experience with silicon.
Me too :) Absolutely every HDMI related chip I examined specs for and tested, including the cheapest of the cheap ones made as HDMI repeaters for splitters and audio extractors, supported DSD stream passing (Both up and down stream), just as they did all other audio bitstreams.
Because they just need to copy the packets from the input to the output.
Can you please point out a specification or other document that say otherwise?
For PCs, all HDMI outputs are handled with HDA controllers. The HDA specification does not mention DSD. AMD's HDA verb documentation has the following list of audio formats codes: 0: reserved 1: LPCM 2: AC-3 3: MPEG1 (Layers 1 and 2) 4: MP3 (MPEG1 Layer 3) 5: MPEG2 (Multichannel) 6: AAC 7: DTS 8: ATRAC 9: Reserved 10: Dolby Digital + 11: DTS-HD 12: MAT/MLP (Dolby True HD) 13: Reserved 14: WMA Pro
Would DSD be one of the reserved ones?
As you say, these are rather straightforward to implement
... if one bothers to implement it.
Same specification also described DSD stream setup, which is is essence exactly the same, just uses the different identifiers.
So the hardware needs some mechanism to output these identifiers.
HDMI only requires 48kHz 2ch really.
Even the HDMI version 1 requires "8 channel LPCM, 192 kHz, 24-bit audio capability": http://en.wikipedia.org/wiki/HDMI#Version_comparison
That page lists the version where a feature was introduced; these are not requirements.
The HDMI specification says: | If an HDMI Source supports any HDMI audio transmission, then it shall | support 2 channel L-PCM ..., with either 32kHz, 44.1kHz or 48kHz | sampling rate and a sample size of 16 bits or more. [...] | An HDMI Sink that is capable of accepting any audio format is required | to accept two channel ... L-PCM audio at sample rates of 32kHz, | 44.1kHz, and 48kHz.
Regards, Clemens