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

[Anssi Hannula]

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.



> 
> On 12/31/2014 10:28 PM, Yang, Libin wrote:
>> Hi Xuebing,
>>
>>
>>> -----Original Message-----
>>> From: Anssi Hannula [mailto:anssi.hannula at iki.fi]
>>> Sent: Wednesday, December 31, 2014 9:41 PM
>>> To: Xuebing Wang
>>> Cc: alsa-devel at alsa-project.org; Yang, Libin; Lin, Mengdong; ; Takashi Iwai; ;
>>> Wu Fengguang
>>> Subject: Re: [alsa-devel] DSD over HDMI: audio data packetization
>>>
>>> 31.12.2014, 15:32, Xuebing Wang kirjoitti:
>>>> Hi Community,
>>> Hi,
>>>
>>>> I am trying to implement DSD (one bit audio) over HDMI, for Intel
>>>> integrated graphics. I am referencing HDMI specification 1.3a.
>>>>
>>>> Regarding audio data packetization, I am referencing spec:
>>>> 5.3.4 Audio Sample Packet
>>>> 7.6 Audio Data Packetization
>>>>
>>>> Q1) Would you please point to me where is the source code to handle
>>>> L-PCM audio sample packetization (to implement 5.3.4 Audio Sample
>>>> Packet)?
>>> It is done by the hardware.
>>>
>>>> Q2) I admit that I did not carefully read HD-Audio specification. Is
>>>> this possible that this L-PCM audio data packetization is done by
>>>> *hardware* (e.g HDMI related widgets/pins)?
>>> Yes.
>>>
>>>> Q3) Did we implement "7.2 Audio Sample Clock Capture and Regeneration"?
>>> That is done by hardware. With some HDA codecs the video driver calculates
>>> the N/CTS values "manually", but AFAIK not on Intel HW.
>> As the N/CTS need fs and frequency of TMDS info, the hdmi driver does not
>> implement this feature.
>>
>> We currently are designing an audio link between audio subsystem and other
>> components, like video or USB.
>>
>> Maybe we will add the N/CTS information transmission. So we can calculate
>> the N/CTS value in audio or gfx driver.
>>
>>
>>>> Thanks.
>>>> Xuebing Wang
>>>>
>>>>
>>>
>>> --
>>> Anssi Hannula
> 


-- 
Anssi Hannula