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

[Xuebing Wang]

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.


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

-- 
Thanks,
Xuebing Wang