Automatic Television Commercial Volume Limiter/Regulator

[ccurtis]

A compressor will boost lower levels as well as limit peak levels. That is not a bad thing for the problem at hand. The average level will be relatively constant and can be adjusted to a comfortable level. Soft sounds and loud sounds more closely approach the same loudness. As long as the loudness is adjusted to a comfortable level, soft and loud sounds will be rendered at a fairly comfortable level.

I have two modern TV sets (not HDTV) with a selectable dynamic range compression feature built in. I have it selected on both TVs continuously. It's a very welcome feature. It is not just the commercials that are annoying, but the average level when changing from one channel to the next can be quite different. It's also nice that I don't have to turn the volume up to hear quite voices in a movie scene when someone in the house is sleeping, only to find that the next scene blasts through the walls. I do not notice any adjustments made by the feature as the level varies. If you are interested in high fidelity, however, you will want to turn the feature off, but even so, the fidelity is pretty good.

 

[arizonaguide]

I have two modern TV sets (not HDTV) with a selectable dynamic range compression feature built in. I have it selected on both TVs continuously. It's a very welcome feature. It is not just the commercials that are annoying, but the average level when changing from one channel to the next can be quite different. It's also nice that I don't have to turn the volume up to hear quite voices in a movie scene when someone in the house is sleeping, only to find that the next scene blasts through the walls. I do not notice any adjustments made by the feature as the level varies.

EXACTLY!!!
Anyone have any schematics on this type of circuitry? That is exactly what I would like to have on my Cablebox Audio Outputs, before it enters my Bose sound system. With Stereo Inputs on one side (from the Cablebox), and stereo out (to the soundsystem) on the other.

PS: CCURTIS, what TV make and models do you have that have this feature and you are happy with?
That may be my next investment if I can't find the circuitry on my own. I'm on a mission! (to save my hearing and sanity).

You are right on the money...it's not just the loud commercials (REALLY LOUD!), but the lack of an intelligable voice track.

In order for me to follow the dialog of the TV show, I have to have it louder than the wife likes. Not because of lack of volume, but because the surround sound DROWNS out the voice tract. I cant hear the freakin talking because the damn city bus (or whatever) in the background is so loud in relation to the voice tract. If I can amlify just the voice track, it would help watch the TV show a lot! I already have the volume up pretty loud...and STILL can't make out WTF they are saying!

Then if the characters have a thick Bronx or Boston accent, it's almost hopeless (I'm from out West)...and the subtitles for the hearing impaired has to get turned on (and I may just go to this full time, and mute the program entirely, if I can't find a solution!).

 

[HarveyH42]

Maybe out dated or completely wrong... But, isn't there a few milliseconds of dead air time between the programming and commercials, which was once used to cut the commercials when recording shows on tape (Beta-max) .

 

[ccurtis]

On is an RCA set. RCA calls it "Sound Logic™": "Provides consistent volume levels throughout programming & channel changes. Eliminates annoying "blast" of sound during some commercial breaks." This is a similar model so maybe you can look up the schematic. **broken link removed**

The other is a Toshiba which calls the feature "StableSound". It is similar to this set **broken link removed**

 

[arizonaguide]

CCurtis,

Bless you, my friend!

 

[arizonaguide]

It looks like the circuitry is called an "Audio Leveler" or "Electro-Optical Leveling Amplifier" in the music industry...and the google search resulted in the Universal Audio LA-3A Classic Audio Leveler @ $1,699.00 retail. It seems the "heart" of the unit is the Electro Optical attenuator.

The two adjustable variables on the front of the unit are PEAK REDUCTION and GAIN.

It sounds like to even build one would require some SPENDY parts.
So, probably the easiest solution is to go with your RCA or Toshiba.

I still agree with Gary350 (above) that there is an aftermarket business opportunity for this circuitry/component...to add to people's existing systems.

 

[killivolt]

Maybe out dated or completely wrong... But, isn't there a few milliseconds of dead air time between the programming and commercials, which was once used to cut the commercials when recording shows on tape (Beta-max) .

Right I was thinking of the same thing during the vertical Blanking period.

I looked up something and found there is a Blank period and is in the Black level.

Improved television commercial monitor device. - Patent EP0158293


This is way over my head. But, I was thinking if you could anticipate the blanking then you could be ahead of the audio signal and could apply the circuit at that moment ?

With a circuit already developed post tense not applicable.

kv

 

[ccurtis]

This is what RCA has to say about their Sound Logic circuit in a Technical Training manual I found. One wonders what the algorithm is they mention. [Sorry about the quality of the file.]

 

[arizonaguide]

Thanks CCurtis!

I also have been poking around the computer software.
I wonder if something like this would work?
**broken link removed**
**broken link removed**

 

[ccurtis]

That seems like overkill to me.

 

[Mr RB]

You do not want a compressor. The "too loud" problem is caused by a compressor that limits the peak volume then boosts the average volume.
...

A compressor is the best solution. A dynamic compressor will have almost NO effect on the loud commercials (is they remain the same volume) BUT it will raise the volume of the program to be the same as the commercials.

This problem is running rampant now most of the networks transmit the program using Dolbyxxx which has a huge dynamic range (so speech is very quiet and explosions are loud).

If you set the compression too high you get an effect called "ducking" where the loud stuff like commercials is actually made quieter and the quiet program stuff (like speech) gets louder. It will affect the sound though as each sound peak will come through before the compression fully hits so it makes it "quacK' a bit hence the term ducking.

I've wanted to build a stereo dynamic limiter for some time for my TV. It should be pretty simple to build one that cranks up the low speech level of the program content to the same level as the commercials.

 

[arizonaguide]

A compressor is the best solution. A dynamic compressor will have almost NO effect on the loud commercials (is they remain the same volume) BUT it will raise the volume of the program to be the same as the commercials.

This problem is running rampant now most of the networks transmit the program using Dolbyxxx which has a huge dynamic range (so speech is very quiet and explosions are loud).

I've wanted to build a stereo dynamic limiter for some time for my TV. It should be pretty simple to build one that cranks up the low speech level of the program content to the same level as the commercials.

Yes, it makes sense that if the TV show were amplified/compressed/decompressed to the same level as the commercials, then your secondary audiosystem volume could be set once, and left alone. If you get the circuit designed, let me know!

 

[killivolt]

What about Voice recognition. You could put it into a Codec like a Streaming Server if the current program were Allowed between 1-2 minutes you could process it. mod and demodulate

I have an AP on my Iphone that will listen to a sound track and then compares it to known songs in their data base then reply with the Artist and song information this all happens in a very short amount of time.

Digital TV should have encoding which could be stripped of the start and stop bits. Problem with that is you have no way of knowing where the coding exists in the program unless of course the first commercial in the program could be read. Giving a Clue.

You would have complete list of commercials recorded and if needed you could send that to a data base file with a complete log of commercials that have been edited out of the programming your comparison software would have ready available samples to compare and edit to be sent on for viewing.

kv

 

[Nigel Goodwin]

It looks like the circuitry is called an "Audio Leveler" or "Electro-Optical Leveling Amplifier" in the music industry...and the google search resulted in the Universal Audio LA-3A Classic Audio Leveler @ $1,699.00 retail. It seems the "heart" of the unit is the Electro Optical attenuator.

Rather a rip-off price - the 'electro optical attenuator' is just a small incandescent bulb heatshrunk to an LDR.

It's a common cheap and easy way of doing it, and the incandescent bulb automatically performs a fairly reasonable attack and decay.

For a simple limiter you might look at:

**broken link removed**

or this compressor/limter:

**broken link removed**

 

[arizonaguide]

Sweet!

THANK you Nigel!
Much appreciated.

And great links to other projects there also. Looks like I have more projects than time again (finally)
It's FUN to get back into this stuff, and GREAT SITE (Electro Tech)!

 

[ccurtis]

Here's is another audio ALC to look at, AZ. Figure 17. It's a 2 channel device so it can be used for stereo.

ftp://trf.education.gouv.fr/pub/edutel/siac/siac2/jury/2004/agreg_ext/get/EN%20documents/106-noteappline570.pdf

 

[arizonaguide]

Thanks folks! GREATLY appreciated.

 

[flat5]

Thanks Nigel. I was thinking of posting about that method.
I built one in the 1970s from an article in Popular Electronics I think. It worked. You could switch it to compress or expand by flipping the bulb/resistor series connected to signal and ground. My memory is very fuzzy on this circuit.

I think it will work because this problem is more about average power than peak voltage.