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

[Andrej Falout]

Hi Anssi,

I think the One-Bit Audio and DST formats are just misnamed here and
> can't be carried over IEC 61937 (ATRAC can be) - the IEC 61937
> specification does not cover One-Bit Audio or DST.
>

Does it have to be? Given that it is defined in CEA 861, and that 61937-1
makes specific provisions for non-PCM data:

Page 16:

"In cases where the interface is used to convey non-linear PCM audio
bitstreams..."



>
> I think the "third-party solution" refers to a driver implementing
> support for a non-HDA-spec HW feature which allows One-Bit audio / DST /
> raw packets to be transmitted (in a similar way "EPT" (Encoded Packet
> Type field in Pin Widget Control 7.3.3.13) allows setting HBR or ASP
> packet transmission).
>
>
Why would an "HW feature" be required to "allows One-Bit audio / DST / raw
packets to be transmitted"?

What would such "HW feature" do? What could it possibly do?


Thanks,
Andrej Falout




>
> > Thanks,
> > Andrej Falout
> >
> > On Mon, Jan 5, 2015 at 4:46 PM, Anssi Hannula <anssi.hannula at iki.fi
> > <mailto:anssi.hannula at iki.fi>> wrote:
> >
> >     04.01.2015, 05:10, Xuebing Wang kirjoitti:
> >     > 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.
> >
> >     That setting will still not allow you to send One-bit audio or DST
> >     packets. The stream will still be encapsulated in either ASP or HBR
> >     packets, depending on the value of the EPT field (Encoded Packet
> Type,
> >     7.3.3.13).
> >
> >
> >     >
> >     > 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
> >     <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
> >     <mailto: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).
> >     >
> >     >
> >
> >
> >     --
> >     Anssi Hannula
> >
> >
>
>
> --
> Anssi Hannula
>