Re: [RFT] Major snd_hda rewrite

2012/1/24 Alexander Motin <mav_at_freebsd.org>

> On 01/25/12 00:33, Alexander Motin wrote:
>
>> On 01/25/12 00:13, Mickaël Maillot wrote:
>>
>>> 2012/1/24 Alexander Motin <mav_at_freebsd.org <mailto:mav_at_freebsd.org>>
>>> Here is it: http://people.freebsd.org/~__**mav/hda.HBR.patch<http://people.freebsd.org/~__mav/hda.HBR.patch>
>>> <http://people.freebsd.org/~**mav/hda.HBR.patch<http://people.freebsd.org/~mav/hda.HBR.patch>
>>> >
>>> It should activate HBR mode if you try to play stream with AC3
>>> format and 8 channels (>6Mbps).
>>>
>>> no change with the patch because when i SNDCTL_DSP_SETFMT to AFMT_AC3,
>>> SNDCTL_DSP_CHANNELS always return 2 channels even if i
>>> set SNDCTL_DSP_SPEED to 192000.
>>> and i think it's why "if ((ch->fmt & AFMT_AC3) && (cchn == 8))" can't be
>>> true.
>>> i checked my /v/l/messages and saw PCMDIR_PLAY ....chan_count=0x01.
>>>
>>
>> Number of channels should be set to 8 by application when it expects bit
>> rate above 6Mbps. Sample rate, as I've described, just give more fine
>> control. Increasing sample rate does not automatically increase
>> channels. They are orthogonal:
>> Rate 48 96 192 48 96 192
>> Channels 2 2 2 8 8 8
>> ------------------------------**----------------------------
>> Mbps 1.5 3 6 12 24 49
>>
>>
ok so set 8 channels is just to allow more bandwidth.
i just looked at alsa hdmi code (because i never find oss code that can
play hd audio),
they set 192k and 8 channels for every DTS HD / TRUEHD / E-AC3 file, so i
was thinking to do the same.


> What I've forgot is to allow 8ch format. :) Add the patch below. Hope
>> sound(4) has no other limitations for it.
>>
>
> Hmm. Looks like there is some limitation. You may grep kernel for
> AFMT_PASSTHROUGH and find two "XXX force ..." comments and code, including
> forcing 2 channels for AC3. Luckily for not part for frequency is commented
> out. Further we may try to comment or modify part about number of channels.
>
>
spotted and commented


>
>  --- hdaa.c (revision 230511)
>> +++ hdaa.c (working copy)
>> _at__at_ -4979,6 +4979,8 _at__at_
>> }
>> if (HDA_PARAM_SUPP_STREAM_**FORMATS_AC3(fmtcap)) {
>> ch->fmtlist[i++] = SND_FORMAT(AFMT_AC3, 2, 0);
>> + if (channels >= 8)
>> + ch->fmtlist[i++] = SND_FORMAT(AFMT_AC3, 8, 0);
>> }
>> ch->fmtlist[i] = 0;
>> i = 0;
>>
>> But in your case I think it should be enough to just increase sample
>> rate to 96 or 192KHz.
>>
>
>
so if my problem persist after settings 8 channels, i'll blame xbmc oss
part.