[mythtv] [mythtv-commits] Ticket #1104: multichannelaudio support

[Paul Catchpole]

Paul Catchpole wrote:
> Paul Catchpole wrote:
>   
>> Ed Wildgoose wrote:
>>   
>>     
>>>> It works fine with the audio device for the frontend changed to a 
>>>> 2-channel one. It's only when using the real 6-channel device and hence 
>>>> the upmixer where the clipping occurs.
>>>>   
>>>>     
>>>>       
>>>>         
>>> #Often you have multiple volume controls for multichannel versus two 
>>> channel - perhaps the multichannel mixer is too loud and causing the 
>>> clipping?
>>>
>>> Ed
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>>>   
>>>     
>>>       
>> The 2-channel device used for testing is a simple ALSA upmixer with an 
>> additional soft-volume added on top. I set the relative mixer levels a 
>> long while ago and they've not changed since. I don't have a master on 
>> this card, hence the softvol. I don't change the levels to test the 5.1 
>> direct output, just move to another device which is the surround51 with 
>> a softvol on top.
>>
>> For the previous testing I did of patch-38 [I think], where I had 
>> clipping problems, I tried reducing mixer levels to no avail - the 
>> 'clipped' output just happily scaled with the rest of the sound.
>>
>> I think Mark is probably correct in thinking it's a mathematical issue 
>> with the new upmixer code, which seems to use lots of floating-point 
>> maths...
>>
>> PC
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>>   
>>     
> Cheers for the patch, Mark.
>
> Recompiling with patch-42 now.
>
> Ta,
>
> Paul
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>   
Initially, I'd say 'top banana' - mythmusic is now working really well. 
The upmixer sounds excellent with the few tracks I've tried...

I'll try a few TV channels and some recordings then report back.

I did notice that with -v audio set, I get a lot of the following 
messages in the log:

2008-01-12 20:53:34.313 AO: Needs upmix
2008-01-12 20:53:34.313 AO: no change exiting
2008-01-12 20:53:34.313 AO: Needs upmix
2008-01-12 20:53:34.313 AO: no change exiting
2008-01-12 20:53:34.314 AO: Needs upmix
2008-01-12 20:53:34.314 AO: no change exiting
2008-01-12 20:53:34.314 AO: Needs upmix


Thanks for the work, Mark.

PC