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

[Paul Catchpole]

Mark Spieth wrote:
>> I've one problem with it, now we've been using it for a few hours - I'm
>> getting a crackle from the centre speaker which is intermittent although
>> not random. It varies from a sharp click, to a buzz and is in sync with
>> the sound on the channel. It has the following characteristics:
>>
>> * Master output volume level changes the volume of the click, but
>> doesn't alter its proportion to the other sounds.
>> * Changing the centre channel mixer level makes the clicking quieter,
>> but doesn't alter its proportion to the other sounds on the centre 
>> channel.
>>
>> I'm getting the feeling that it is directly proportional to the quantity
>> of very low frequency sounds in the source. It was particularly bad
>> earlier on 'Creature Comforts' and is extremely bad, now and again,
>> watching [well, my better half is] the X-Factor. Commercials almost
>> always don't cause it. It does happen on the news channels.
>>
>> I know that's perhaps not a lot to go on, but if you've any ideas I'd
>> appreciate it.
>>     
>
> in el_surround.cpp line 74 (setting wnd in loop with sqrt) there is a 0.5 
> commented out. uncomment it so that the 0.5 factor is included. I suspect 
> the clicking is float to short conversion issues. this will decrease the 
> overall gain of the upmixer. let me know if it works for you. everything Ive 
> tested with shows the current value ok but more testing will prove/disprove 
> this.
>
> mark
>
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>   
I've made the change - in el_processor.cpp, you meant?

Recompiling now - I'll let you know how I get on.

The clicking is an odd one. Jurassic Park went by with no clicking 
whatsoever, but Red Dwarf on BBC2 was awful. Odd!

PC