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

[Anssi Hannula]

06.01.2015, 06:33, Andrej Falout kirjoitti:
> Hi Anssi,

Hi,

> Just wondering how Microsoft documentation fits into this discussion:
> 
> "Representing Formats for IEC 61937 Transmissions"
> 
> http://msdn.microsoft.com/en-us/library/windows/desktop/dd316761%28v=vs.85%29.aspx
> 
> 
> "Microsoft-provided HD Audio class driver supports PCM, AC3, DTS, AAC,
> Dolby Digital Plus, WMA Pro, MAT(MLP) formats. The GUIDs for the
> compressed audio formats that are not supported by the HD audio class
> driver and can be implemented by third-party solutions are listed in the
> following table. "
> 
> CEA 861 Type	SubFormat GUID	Description
> 0x08	
> 
> 00000008-0cea-0010-8000-00aa00389b71
> 
> KSDATAFORMAT_SUBTYPE_IEC61937_ATRAC
> 
> 	Adaptive Transform Acoustic Coding (ATRAC)
> 0x09	
> 
> 00000009-0cea-0010-8000-00aa00389b71
> 
> KSDATAFORMAT_SUBTYPE_IEC61937_ONE_BIT_AUDIO
> 
> 	One-Bit Audio
> 0x0d	
> 
> 0000000d-0cea-0010-8000-00aa00389b71
> 
> KSDATAFORMAT_SUBTYPE_IEC61937_DST
> 
> 	Direct Stream Transport (DST)—lossless compressed DSD (Direct Stream
> Digital).
> 
> 
> And knowing that IEC 61937 from HDMI 1.3 also supports above 6.144 Mbps...
> 
> Is there a doubt that above information is correct, and that DST/DST can
> be carried over 61937 in Microsoft HDA class driver, in this example, by
> "implementing a third-party solution" as described in this table?


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.

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).


> 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