Someone please explain "DRC"

[Bodymechanic]

OK, Dynamic range compression. I can't really seam to find an explanation that I completely understand. My DVD player has it. My receiver has it.

Here's a little history: I have a yamaha rx-v2500, an oppo dvd player and all axioms. VP150, M22Ti' mains, QS8 surrounds and an EP350. I like to let the yamaha handle all adjustments possible so the sub is on bypass and the Yamaha sets crossover to 90, all LFE to the sub and all other speakers set to "small". I let the YPAO do a complete auto set-up and then made some fairly minor adjustments from there. The Oppo has a DRC function which I have set to zero or none. I have run my YPAO in all possible auto set-up configurations and each time it sets the DRC to Max (possibilities are MAX, STD and MIN).

While watching movies at a loud playback level between -12 and -5 things sound great. Tonight, however, we were watching Star Wars 3 and although it sounded good there seamed to be something lacking. The sound was very wide with lots of music always playing in the background. The effects were right on cue, no delay issues. But sometimes a spaceship would fly by or blaster fire would errupt and you expected things to sound one way and instead they seamed just slightly muted. I couldn't be sure if it was intended that way or if something were amiss. I experimented a little during playback switching from THX to Movie: Sci-fi and a few others. The phenomenon, if you will, persisted at all times.

Later I thought I'd experiment a bit more with some familiar material. I chose "the Incredibles". In particular, chapter 9. In the middle of this chapter, Mr Incredible is fighting a large robot in the jungle. As he leaps over it the robot bats him into a tree and the tree topples over. With "MIN" DRC most of the effects sound accurate but you don't really notice the sound of the robot when it hits Mr Incredible and the sound of the tree hitting the ground is almost completely lost. This issue improves somewhat whith DRC set to "STD" and then improves to an excellent (amazing really ) and accurate reproduction when I return DRC to "MAX".

So, whats the deal? From what I gather the DRC at max is only supposed to be good for low volume night viewing, etc.. After hearing material at high volumes with max DRC I don't think I would enjoy it as much with less compression. Is compression a good thing? Am I missing the sonic holy grail of home theater by using it? If it is soooo great should I double up and experiment with adding more compression from the Oppo DVD player? Should I just use the Oppo DRC and not the Yamaha's DRC? The instruction manuals make no attempt at explaining any of this. The authors of such manuals must assume that this is basic information covered in grade school!

If anyone can make sense of this madness it's you resident experts. I thank you, in advance, for your time in helping me find my 'happy place' again

Kind regards,

BM

 

[mulester7]

Dynamic Range

Difference between the highest and lowest sound levels a sound system reproduces; also the difference between the overload level (the highest possible output) and the noise floor (point where output is at a minimum – if output goes lower it is obscured by distortions or noise making it unusable).

Dynamic range is measured in decibels (dB) with a higher number being better. The higher the dynamic range the more a particular audio component can output undistorted sound from a low level to a high level.

Think of dynamic range as the speed of a car, the more power the engine has (a better system) the faster the car can go (to a certain level). A car with a small engine would have low dynamic range – it could not move very quickly or powerfully. A car with a large engine (a superior system), however, could move quickly and powerfully having a high dynamic range. To reproduce loud, sudden sounds a system must have a good dynamic range.


Compression

Method for shrinking down data to fit in a smaller space than it would normally occupy. Compression takes data and makes it smaller using various methods. The benefit of compression is that more information can be held in a smaller space.

Compression is common in both video and audio. The most common form of video compression is MPEG-2 compression used with digital television, DVD and direct broadcast satellite. A common form of audio compression is Dolby’s AC-3 technique used in Dolby Digital surround sound.

Some forms of compression use mathematical formulas or algorithms to shrink data and than reproduce it later exactly as it was before compression. Another form of compression used in AC-3 and other sound compression formats eliminates information that is not perceived by human hearing (people cannot hear crickets for instance when a bomb goes off so the information used for the cricket chirps is discarded). This type of compression is called lossy compression because information is lost in the compression process – the end signal when decompressed is not the same as the original signal before undergoing compression. The goal of compression is to make information smaller so that it can travel faster or take up less space when stored.

http://www.audiovideo101.com/dictionary/default.asp

 

[tbewick]

The dynamic range compression can be thought of as lowering the volume of loud parts of a soundtrack and boosting the volume of quieter parts of the soundtrack. How things sound when using DRC is decided by the producer of the soundtrack.

It's really up to you whether you want DRC on or off. I'd recommend using it if some parts of the speech in a film are hard to discern. When I saw Star Wars episode 3 in the cinema, it didn't have a very loud soundtrack, in fact it was quite quiet.

 

[RJB]

Good technical replies guys but I don't know if you really answered Bodymechanics question.

I would have to ask the same questions regarding DRC. It's not explained very well in any of the equipment manuals I have, and by default it's set to "MAX" or "ON" on both my A/V receiver and DVD player.

Is this one of those situations that's similar to the bass management issue many people have where bass management should be done by the A/V receiver alone, if possible, and not duplicated on the sub? IE. avoiding the "doubling up effect".

Any suggestions for a "rule of thumb" for DRC settings when they are available on multiple devices in the chain would be helpful...I have tried playing around with the settings myself and have had mixed results as far as my preferences go, but then again, I'm not really sure what I should or should not be hearing.

 

[MDS]

Don't worry BodyMechanic, you are not alone. It seems many Yamaha owners are confused and rightly so - the settings are confusing because Dynamic Range and Compression are two different things and the choices on the Yamaha don't make sense.

Dynamic Range is as in mulester's definition: the difference between the softest and loudest sounds.

Compression in this case refers to reducing the dynamic range so that the loud parts aren't as loud (not lossless or lossy data compression).

I think the Yamaha settings are confusing because of the choice of Min, Max, and Standard. Does Max mean Maximum Dynamic Range or Maximum Dynamic Compression? Likewise for the others.

It does in fact mean Max Dynamic Range - therefore NO compression.
Min is a minimum amount of compression.
Std is the 'standard' amount of compression - whatever that means.

[Contrast that with Onkyo - Off, Low, High - very straightforward]

You want to leave DRC off on the dvd player and use the receiver's DRC when you want to compress the range. Late at night when you don't want to disturb others or you just want to reduce the loudest parts. It is useful for movies with a large dynamic range where the dialog is very low but then there are huge explosions or loud music. Setting a little compression will bring the loud peaks down (thus raising the average level) and making it easier to hear everything.

Note that DRC only works on DD tracks. DD has cues in the bitstream that help the receiver determine how to do the compression.

 

[RJB]

Thank you, thank you, thank you MDS!

That's the explanation I was looking for. I now have a better understanding of what's taking place so I can make a more informed choice of settings...

 

[Bodymechanic]

Thank you all for your input. MDS your post was what I was hoping for. I went back and re-read my manual, yet again, and sure enough you are right. Below the dynamic range area there is a mention about headphones (I glossed over this part before) and it says "MAX" to preserve the greatest amount of dynamic range.

Tbewick pretty much nailed what I was trying to say about Star Wars 3. It just seamed oddly quiet at times when I wouldn't have expected to be.

Thanks also Muelster. WOW! Nice definition!!

I have found my 'Happy Place'

Kind regards