[pulseaudio-discuss] [RFC PATCH 0/2] HDMI IEC61937 + HBR passthrough support

[Pierre-Louis Bossart]

On 8/28/17 11:28 PM, Alexander E. Patrakov wrote:
> 2017-08-29 3:49 GMT+05:00 Pierre-Louis Bossart
> <pierre-louis.bossart at linux.intel.com>:
>> HDMI passthrough needs some love. What works with ALSA is plain
>> broken with PulseAudio (no audio or random noise). Only the AC3
>> format seems to work, EAC3 is broken and HBR formats are not
>> supported yet.
>>
>> Fix EAC3 issues where the AES non-audio bit is not set when opening
>> the alsa-sink. The fix is to force a suspend/resume when an actual
>> sink-input is connected. This is far from optimal since we suspend/resume
>> twice (once for rate, once on entering passthrough) but the state
>> machine is obviously quite racy.
>>
>> Add definitions for Dolby TrueHD and DTSHD. This needs additional
>> work since ALSA will only enable the HBR passthrough mode with
>> 8 channels and 192kHz. For now the ALSA sinks are only configured to
>> support 2 channels for passthrough and we'd need to switch between 2
>> and 8 channels depending on the format. I don't quite understand how
>> the profiles are managed and could use some help here.
> 
> Your work invalidates the comment added in this commit:
> 
> https://cgit.freedesktop.org/pulseaudio/pulseaudio/commit/?id=04737989ec537e01d63c155807a5d19b0ec5b294
> 
> I think that, if you don't undo this commit, at least a better message
> what exactly works is needed. I.e. how to test, given that the HDMI
> sink does not have the formats set.

I don't understand what set_format does and how the profiles are 
managed. The point is that we still want to keep the check when HBR is 
not used, and I just don't have any hooks to change the logic.