[alsa-devel] Audio Mini Conference Minutes - Edinburgh 21st October 2013

[Wang Xingchao]

Hi Anssi Hannula ，

2013/11/22 Anssi Hannula <anssi.hannula at iki.fi>:
> 21.11.2013 20:22, Mark Brown kirjoitti:
>> On Mon, Nov 18, 2013 at 05:35:42PM +0000, Liam Girdwood wrote:
>>> On Sat, 2013-11-16 at 17:01 +0800, Wang Xingchao wrote:
>>
>>>>> We could use offload, on roadmap for Hires audio on android PCM,
>>>>> maybe float instead of 24 bit. Need for 192kHz, Probably not use effects.
>>
>>>> Does android support HBR audio now? As i know from Dolby guys, no
>>>> customers in Android area are buying Dolby TrueHD license, so i guess
>>>> the answer is NO. Most of the customers are from AV receivers and
>>>> BlueRay players.
>>
>>> Afaik, no one is using high Bit rate audio atm, but there is increasing
>>> interest amongst Android OEMs.
>>
>> There's a few things shipped doing 192kHz/24 bit - the LG G2 was one of
>> the first IIRC.
>
> At least Wang Xingchao seems to be talking specifically about HBR in
> relation to HDMI specification, i.e. compressed audio, not PCM...
>
> HBR audio is the way high-bitrate (over 6.144Mbps) compressed IEC 61937
> streams are bitstreamed through HDMI. The only such formats supported by
> IEC 61937 are DTS-HD MA and Dolby TrueHD (MAT), used on e.g. Blu-ray discs.
>
> The only in-tree ALSA driver supporting HDMI HBR is HDA, AFAICS.

I think that depends on vendor's HDMI controller, not only the HDMI
Specification version.
And HDA seems the first one claims supporting HBR, i donot see any
other ARM based Soc
has such claim.

Lots of HD video sources are using HBR audio, and lots of set-top
boxes/TV(ARM based) have
the requirements to paly HBR audio in HDMI passthrough mode. Currently
the solution is from vendor specific, they downmix HBR audio
into 5.1 or Stereo.

thanks
--xingchao
>
>>> Most of the x86 and ARM HW will support HBR audio over ASoC PCM DAIs and
>>> HDA, but I'm not sure about which HDMI audio devices support HBR in HW
>>> atm...
>>
>> It should be relatively common I suppose given that video sources have
>> tended to use HBR for a long time (even DVDs do it as standard), though
>> it's possible the mobile
>> chipsets are limited in some way.
>
> Video DVDs only do PCM, AC-3, DTS and MP2.
>
> --
> --
> Anssi Hannula