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

[Yang, Libin]

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.

> 
> 
> >
> > 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