[vlc-devel] Re: your vlc audio patch

[Mark Wells]

Matt,

Thanks for your reply, it helps to explain my situation pretty well. So 
if I isolate a specific audio format (eg 6-channel) by commenting-out 
all the other support (except mono) then the AC3 stream plays 
perfectly. I *think* that once specific format selection works (ie once 
the menus successfully allow you to change between stereo, 5.1, 7.1 
etc) then this problem will disappear.

To answer your question, I'm testing using one of our own devices, the 
OXFW970 (http://www.oxsemi.com/press/jan04/index2.html).

An update so far, for anyone interested.....

I notice that in ChannelsToAoutVar there is a 5-channel support option 
(3 Front 2 Rear) however there is no initial 5 channel PCM support 
available to complement this! So I have added this, and opened the 
correct physical channels. The channel allocation seems to be all wrong 
tho, as main audio comes out of channel 1 (front left). 2&3 and 4&5 are 
the stereo pairs, but I havent figured out which pair is front/surround 
yet.

Further, if I play 5-channel content in a 6-channel environment then 
channel 4 is empty, channel 5 plays what was in channel 4, and channel 
6 plays what was in channel 5 (compared with the 5-channel 
environment). Playing 5-channel content in an 8-channel environment 
reverts back to the configuration in the 5-channel environment, but 
duplicates channels 1-3 on 6-8. Channel-duplication is annoying but 
tolerable. However channel-switching is not tolerable! im working on 
it!


Mark


On 23 Jun 2004, at 03:37, Matthew Romaine wrote:

>
> Mark,
>
> Sorry for the late response; I was away from my desk for the past 
> couple days.
>
> AC3 has not been tested because it was special cased in the original 
> module and I don't have source material to test it out yet.
>
> i've only tested my patch on two devices - RME Hammerfall, which 
> deinterleaves multichannel streams, and MOTU 896, which uses single 
> interleaved streams.  Combinations of the two (interleaved and 
> deinterleaved) should also be possible but is untested :)
>
> as for the error, without looking at the code i think I put in that 
> error message to indicate when a different physical format had to be 
> chosen but a corresponding channel count wasn't found.  In other 
> words, some devices allow for multiple formats under a single stream - 
> i.e. "Stream 1" could have two physical formats, one that handles 4 
> channels at 44.1 and another that handles 2 channels at 96.  Due to 
> deinterleaved-implementation constraints (and time :), the code 
> currently only allows a change in sampling rate, so will basically 
> fail if a different physical format in the same stream can not also 
> handle the same number of desired channels.  I *think* that's the 
> error you're getting.
>
> try debugging in extra verbose mode and you should get a clear sense 
> of the possible stream combinations of your device.  what device are 
> you using?
>
> if all else fails, follow the Xine model :)
>
> hth,
> matt
>
>
> On 2004/06/22, at 18:41, Mark Wells wrote:
>
>> Matt
>>
>> Firstly, if you dont have the time to answer this, dont worry i'm 
>> sure I'll figure it out. I just thought it was worth asking incase 
>> you can put your finger straight on it. Im trying to figure out what 
>> capabilities your patch provides, and therefore what the priorities 
>> are for continuing where you left off.
>>
>> As far as I am aware from reading up on the vlc-devel list (correct 
>> me if im wrong) your patch should provide successful multichannel 
>> support for OS X. The only thing it doesnt do is let you choose how 
>> many channels you want to use (ie it always uses the most channels it 
>> can find). Right (in theory) ?
>>
>> I'm testing using an 8-channel audio device (yes, i've uncommented 
>> the 8-channel support) and an ac3 audio stream. When I load the 
>> stream I get the error "Something is wrong with the physical format 
>> indexing i[0] j[2] fmt_idx[5]" I have also tried 6-channel instead, 
>> but get the same error. Having looked at my input stream it seems to 
>> be a single stream (therefore interleaved) with 9 formats.
>>
>> I guess all I'm asking is this: were you/others getting this error 
>> (ie is this something I need to patch up before addressing the 
>> problem of selecting how many channels to use) or is this error new 
>> news to you?
>>
>> Many thanks
>>
>> Mark
>>
>> ----------------------------------
>> Mark Wells
>> Oxford Semiconductor Ltd
>> 25 Milton Park, Abingdon, OX14 4SH, UK
>>
>>
>>
>> On 15 Jun 2004, at 10:40, Matthew Romaine wrote:
>>
>>>
>>> Mark,
>>>
>>> 	Just a quick tip, but be sure to go back over the past couple 
>>> references to multichannel audio on OSX on the mailing list.  
>>> There's a patch I sent out that should work for all devices now that 
>>> interleaved and de-interleaved streams are supported, but it won't 
>>> let you choose which option to use.  It should be a trivial fix, but 
>>> my hands are currently tied.  I've also commented the code heavily 
>>> so anyone should be able to follow.
>>>
>>> But if you're really gonna fix it up, be sure to look up references 
>>> to AUHAL throughout the list to get it done right :)
>>>
>>> matt
>>> ----------------------------------------
>>> Matthew M.I. Romaine
>>> IMNC Audio Codec Group
>>> Sony Corporation
>>> phone: 03-5448-6065
>>> fax: 03-5448-5617
>>> ----------------------------------------
>>>
>>> -- 
>>> This is the vlc-devel mailing-list, see http://www.videolan.org/vlc/
>>> To unsubscribe, please read http://developers.videolan.org/lists.html
>>> If you are in trouble, please contact <postmaster at videolan.org>
>>>
>>>
>>
>>
>>
> ----------------------------------------
> Matthew M.I. Romaine
> IMNC Audio Codec Group
> Sony Corporation
> phone: 03-5448-6065
> fax: 03-5448-5617
> ----------------------------------------
>
>
----------------------------------
Mark Wells
Oxford Semiconductor Ltd
25 Milton Park, Abingdon, OX14 4SH, UK


-- 
This is the vlc-devel mailing-list, see http://www.videolan.org/vlc/
To unsubscribe, please read http://developers.videolan.org/lists.html
If you are in trouble, please contact <postmaster at videolan.org>