[alsa-devel] DSD over HDMI: audio data packetization

[Xuebing Wang]

Anssi, Libin,

Thanks for your help.

After a little bit of research, I do think it is possible to stream DSD
over HDMI (the mechanism is as Anssi mentioned, similar way as HBR).

Please see HDA spec:
3.7.1 Stream Format Structure
(If the TYPE is set to Non-PCM, the controller just pushes data over the
link and is not concerned
with formatting. The base rate, data type, and number of Words (MULT) to
send each valid frame
are specified to control the rate at which the non-PCM data is sent.)

7.3.3.8 Converter Format

What do you think? In order to implement this similiar mechanism
(similar to HBR), I still have some detailed questions that I will write
in another email. Thanks.


On Thu, 2015-01-01 at 06:37 +0200, Anssi Hannula wrote:
> 01.01.2015, 04:07, Yang, Libin kirjoitti:
> > Hi,
> > 
> >> -----Original Message-----
> >> From: Anssi Hannula [mailto:anssi.hannula at iki.fi]
> >> Sent: Wednesday, December 31, 2014 11:45 PM
> >> To: Xuebing Wang
> >> Cc: Yang, Libin; alsa-devel at alsa-project.org; Lin, Mengdong; ; Takashi Iwai; ;
> >> Wu Fengguang
> >> Subject: Re: [alsa-devel] DSD over HDMI: audio data packetization
> >>
> >> 31.12.2014, 17:38, Xuebing Wang kirjoitti:
> >>> Anssi, Libin,
> >>>
> >>> Thank you very much for your help.
> >>>
> >>> If L-PCM audio data packetization is done by hardware, is it possible
> >>> to implement DSD over HDMI on Intel integrated graphics? Thanks again.
> >>
> >> I don't think so, unless:
> >>
> >> (a) It is possible to somehow encapsulate the stream in Audio Sample
> >> Packets and be accepted by the receiver (like e.g. AC3, DTS). I'm not aware of
> >> such a way.
> >>
> >> or:
> >> (b) There is some undocumented feature in the Intel HDMI codecs allowing
> >> the driver to switch to DSD or driver-constructed packets (instead of
> >> ASP) in similar way as there is a way to switch to HBR packets.
> >>
> > 
> > Yes, I agree. And I'm not sure whether HDMI spec supports DSD.
> 
> It does, via the "One Bit Audio" and "DST" formats (spec 5.3.9, 5.3.10
> in 1.3a/1.4a).