[mythtv] [mythtv-commits] Ticket #1104: multi channel audio support

[Paul Catchpole]

Paul Catchpole wrote:
> Paul Catchpole wrote:
>   
>> MythTV wrote:
>>   
>>     
>>> #1104: multi channel audio support
>>> -------------------------+--------------------------------------------------
>>>  Reporter:  Mark Spieth  |        Owner:  ijr 
>>>      Type:  enhancement  |       Status:  new 
>>>  Priority:  minor        |    Milestone:  0.21
>>> Component:  mythtv       |      Version:  head
>>>  Severity:  medium       |   Resolution:      
>>>   Mlocked:  0            |  
>>> -------------------------+--------------------------------------------------
>>>
>>> Comment(by markspieth):
>>>
>>>  36 hopefully will help the buffer underrun issue
>>>
>>>   
>>>     
>>>       
>> Cheers, Mark, compiling now.
>>
>> PC
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>>   
>>     
> Hi Mark,
>
> Patch 36 has fixed the buffer problems and the jittery broken audio, but 
> the 'phasing' echo is still there...
>
> http://www.paulcatchpole.co.uk/images/DM200011.MP3
>
> The link above to an MP3 recording of BBC News shows the problem. It's 
> almost as if each of the speakers was very slightly out of time with 
> each other.
>
> Any ideas?
>
> Paul
>
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> mythtv-dev at mythtv.org
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>   
Cheers, Mark - Patch 38 has fixed the audio echo and the upmix sounds 
great. Is the channel balance configurable anywhere? I could do with 
increasing the rear channel levels a little.

Using the internal player for a DVD shows the following:

No accelerated IMDCT transform found
2007-12-28 12:44:09.853 AFD: Opened codec 0x8917820, id(AC3) type(Audio)
2007-12-28 12:44:09.853 AFD: Audio Track #1 is A/V stream #1 and has 0 
channels in the Unknown language(0).
2007-12-28 12:44:09.871 AFD: Selected track 1: English LIBA52 5.1ch (A/V 
Stream #1)
2007-12-28 12:44:09.871 AFD: Initializing audio parms from audio track #1
2007-12-28 12:44:09.871 AFD: Audio format changed
                        from id(NONE)    -1Hz -1ch   0bps    ; 
id(NONE)    -1Hz -1ch   0bps  
                        to   id( AC3) 48000Hz  6ch  16bps    ; id( AC3) 
48000Hz  6ch  16bps  
2007-12-28 12:44:09.876 AO: Needs upmix
2007-12-28 12:44:09.876 AO: Killing AudioOutputDSP
2007-12-28 12:44:09.876 Opening audio device 'softvol2'. ch 6(6) sr 48000
2007-12-28 12:44:09.876 Opening ALSA audio device 'softvol2'.
2007-12-28 12:44:09.895 in SetParameters(format=2, channels=6, 
rate=48000, buffer_time=100000, period_time=25000)
2007-12-28 12:44:09.895 get_buffer_size returned 4800
2007-12-28 12:44:09.895 set_period_time_near returned 25000
2007-12-28 12:44:09.896 get_period_size returned 1200

The new upmixer is so good, I can't tell whether this is actually using 
the original 6-channel audio or upmixing! I noticed the 'Needs upmix' 
message, despite the device having 6 ch and the source the same. Must 
try and find a DVD with better channel separation to try!

Thanks for working on this patch, Mark, it's definitely something that 
Myth's been waiting for...

PC

PS: Softvol2 is just a softvolume copy of surround51.