[Fwd: Re: Docs]

David Henningsson david.henningsson at canonical.com
Tue Jan 3 07:22:37 UTC 2012

On 01/03/2012 05:20 AM, Len Ovens wrote:
> On Mon, January 2, 2012 1:32 pm, David Henningsson wrote:
>> Musicians is a very diverse group, and the quality required by different
>> musicians is also very different. It's difficult to draw the line here;
>> to know what stuff really matters and where it does not.
>> A side note: Almost all Codecs have very good specs on paper (like DAC
>> S/N>  100 dB, etc), so the quality loss is in general on the analog
>> components outside the codecs.
> Yup, that was what I was saying.
>> For internal mics, an increasing amount of them are being connected
>> digitally, like this:
>> http://www.wolfsonmicro.com/documents/uploads/misc/en/WAN0263.pdf
> That may be the problem I have and why my mic is only 48000. (and has two
> channels out of phase) Except it does make me wonder why the same boost is
> used for external... but then maybe it isn't, just the controls are the
> same. In any case there is still some analogue circuitry from mic to ADC
> somewhere even if inside the mic.

 From the Alsa-info, I can confirm that it is a Digital Mic that is 

>> I'm still very interested in knowing your ALSA info (see
>> http://wiki.ubuntu.com/Audio/AlsaInfo ), can you please give it to me?
> Attached. It says my audio is wonderful. (16/20/24bit,
> 44100/48000/96000/192000) I would guess that these two lines below say the
> mic and external mic pre are separate devices?
> [   20.152166] Bluetooth: RFCOMM ver 1.11
> [   20.344422] input: HDA Intel Mic as
> /devices/pci0000:00/0000:00:1b.0/sound/card0/input8
> [   20.351928] input: HDA Intel Headphone as
> /devices/pci0000:00/0000:00:1b.0/sound/card0/input9

No; that's just related to jack detection.

> Maybe that is why the internal mic sounds so bad at 44100. (the external
> is ok though)
>> (But how many of those would succeed in an A/B listening test?)
> On computer speakers? Even on most people's stereo? For that matter even
> going through a crown amp to bagend speakers most people would not be able
> to tell the difference. In fact most people would pick the loudest ones as
> better no matter the quality. Certainly most people can not tell the
> difference from 16bit to 24bit or 44100 to 96000hz. Two channels to five
> for surround? Most people would notice that. However, multi-track
> recording, effects and mixing start to show funny things much faster than
> playing an MP3s or game sounds. The people who test audiophile cards, test
> them against each other... I don't know what kind of golden ears they have
> though many of the comparisons end up being based on manufactures specs.
> The Intel blurb on HDA is just that, a blurb. There is not link to actual
> specs or users manual for their chips. They do point to the AC97 spec as
> background needed to understand the HDA spec... then give a link to their
> own site... but the document doesn't exist. It all seems to point to HDA
> being a hopped up AC97 with a new interface... with the hopped up part
> being optional...
> To be fair, I did not buy the netbook for sound, I have a desktop with a
> pci mutitrack soundcard for that. It is only as I have been doing test
> installs on it that I wondered what I can do with the audio on it. Can I
> hear the difference between the Delta66 and the AC97?Yes. no problem,

You hear the difference between the Delta66, and the surrounding analog 
components of a chip that implements the AC'97 protocol.

> even using the cheaper/noisier mixer mic preamps in the Yamaha RM602
> designed for tracking to 4 track cassette. (My Mackie pre amps are better)
>> As I've said before, given your alsa-info I might be able to write a
>> driver quirk that turns it into a mono mic at the ALSA level.

Unfortunately, we know how to do this for ALC269 and ALC271X, but we 
don't yet know how to do this for ALC272X. :-( It was worth checking.

> It does already, my recording software reports it as a mono signal. It is
> the manner in which it does so. Alsa seems to mix the two channels
> together. Just use left should work fine.

Yes, but some applications (such as PulseAudio) is not aware of which 
hardware have this problem, so it would still be good if we could just 
ignore the signal at ALSA level.

>>> that all Xubuntu's documentation is copyright the ubuntu documentation
>>> project. Should I be using the same copyright/license (artistic)? Is
>>> there
>>> a template I should be using? Point me at a web page if that is the best
>>> way for you to answer this.
>> I don't know, but if I were you, I would start looking at
>> https://wiki.ubuntu.com/DocumentationTeam
> Thank you.

Should that not work, try someone in the Canonical Community team, they 
should probably know who knows. ( 
https://launchpad.net/~canonical-community )

>> I'm not sure how our different types of documentation are organised, and
>> what types of documentation can go into where based on which criterias,
>> maybe Scott might know more of how that stuff works?
> Ah, no. I think just about everyone now a part of US is pretty much in the
> dark on docs, we all can see we need them. I think Scott has enough to do
> right now.
>> I recently made the general audio troubleshooting sections at
>> https://wiki.ubuntu.com/DebuggingSoundProblems and
>> https://wiki.ubuntu.com/Audio up-to-date.
> I'll use them.
>> Sorry if I sounded harsh. It's just that it's not the first time I see
>> documentation that is based on individual pieces of hardware and the
>> documentation writer making the assumption that everyone else's hardware
>> works the same way. I understand that it is difficult to get the
>> overview - to know what problems are common and thus worth mentioning in
>> a general "help" page, and which ones are not.
> I will see what I can do. Going will be slower now though as I go back to
> work soon... Your comments will help us have better docs, in the end that
> is what I want. I will keep trying to find some real HDA documentation. I
> will list most of what I have as being AC97 info as that is where I got
> it.

> I don't have the resources to try out different hardware and see how
> it works.

And that is the heart of the problem really. The people who have the 
overview, would typically be the ubuntu-audio-dev team (of which I am a 

David Henningsson, Canonical Ltd.

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