Hi there Roman and others,
Yes sometimes the commercials are funny, but i've seen some commercials come on SO MANY TIMES the same exact, dumb, dumb, dumb commercial that it almost gets sickening after a while. In fact it is just plain SICK that the company thinks that people want to see this kind of thing, over and over and over and over. The smartest companies have DIFFERENT commercials come on for the same product, especially when it is the same program (show) it is being used in.
Does it really need to be that hard? If you monitor the average sound level over X time, then turn the gain up or down to give the same average sound level it should work pretty well.
Obviously it needs a limit to how much it will crank up the gain during the quiet program content, but that's not hard really.
The main issue is that the normal program content averaging 0.7v needs to be cranked up to match the advertising sound at average 1.0v.
So it only needs a max gain of maybe 2:1, which should take care of the other issue?
Yes perhaps it isnt that difficult. I was just thinking that when it is quiet for a while and then suddenly the commercial blares we have to have a time constant that is fast enough to catch that and mute that peak but slow enough not to make the regular programming sound unnatural. We could do that i guess.
The unit i am thinking of however would not go between the amplifier and the speaker. It would have to go between the output of the TV and the amplifier input. That's the low level signal that we would modify to get the effect. For a unit to go between the output and speaker we'd have to design a decent audio amplifier too and that's a different project really.
The way i would do it is take the output from the headphone jack and modify that, then run the result into a ready made set of amplified computer speakers. I already have the amplified speakers so all i would have to build would be the compressor itself.
This is one of those things that i have designed several circuits and never built any of them, yet
For the pass/limiting element i propose a home made opto coupler made from a white LED and light dependent resistor in a small light proof package.
Anyone up for trying this?