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

[Anssi Hannula]

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]
>>>> 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).
> 
> 


-- 
Anssi Hannula