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

[Mark Spieth]

> 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