compressor preset for Dolby AC3 encoding

[vudoo]

I just finish a stereo and surround mix for a client. I need to make an stereo AC3 for DVD authoring. I 've read various opinions regarding the '' Compression preset '' in compressor.
It defaults at Film standard compression. I usually have it set at NONE as i don't want ANY alteration done to my mix. Is this the right setting or do DVD desktop and software players need to see a compression setting ? Thanks

[Justas]

I don't usually do myself the AC3 encoding, but I think the right option is "no compression" so there's no level changes.

[kk@jamsync.com]

Originally Posted by vudoo

I just finish a stereo and surround mix for a client. I need to make an stereo AC3 for DVD authoring. I 've read various opinions regarding the '' Compression preset '' in compressor.
It defaults at Film standard compression. I usually have it set at NONE as i don't want ANY alteration done to my mix. Is this the right setting or do DVD desktop and software players need to see a compression setting ? Thanks

These days I use Music Light. Some decoders will slap the last compression setting used or a default setting if they see a null in the bitstream. If you're running a very hot mix, it will crunch it a bit, but nothing like one of the "Film" settings. If you're mixing at a sensible level, it shouldn't slam it too much. Dialnorm I definitely leave at -31, but for compression I have been bitten by crap decoders enough that I have finally learned my lesson and kowtowed to the Dolby suggestions of many discussions past.

[JoeMilner]

Hi KK,
So if you use "None" that will give a null in the bitstream, and automatically switch?
This is great info, I was about to tell a client to use -31 for Dialnorm and "None" for compression......

best,

Joe

[danijel]

Originally Posted by JoeMilner

Hi KK,
So if you use "None" that will give a null in the bitstream, and automatically switch?
This is great info, I was about to tell a client to use -31 for Dialnorm and "None" for compression......

best,

Joe

Joe, I've tested this on at least 3 standalone players and 1 software player - if the DRC values in the bitstream are all zero (which you get when you set the DRC profile to 'none'), they all compressed about the same or harder than with 'Music light' values encoded in. On most DVD players I've encountered (but not on each one), there is the option to turn the DRC off. It will than disregard the DRC bitstream and play full dynamics irregardless of your setting.

[kk@jamsync.com]

Originally Posted by JoeMilner

Hi KK,
So if you use "None" that will give a null in the bitstream, and automatically switch?
This is great info, I was about to tell a client to use -31 for Dialnorm and "None" for compression......

best,

Joe

It depends. On some decoders, especially the more professional ones, you'll get
"none"...no change. However, I've had some experiences, especially with cheap DVD players, where the audio would get slammed and sound horrible.

If the playback device has DRC on, the program will get slammed, so it's a playback issue. Also if the DVD player is playing back in RF mode, it will limit any peaks beyond -11 dBFS.

Since you can never tell if someone knows how to set up a DVD player (I've even had one that seemed to ignore my efforts to turn off DRC), Music Light provides control downstream...to some extent.

As I say, I used to feel differently about this issue, but I've just learned that out in the real world, you can't depend on having a professional decoder, much less someone that knows or cares to set up decode parameters.

[kk@jamsync.com]

Originally Posted by danijel

Joe, I've tested this on at least 3 standalone players and 1 software player - if the DRC values in the bitstream are all zero (which you get when you set the DRC profile to 'none'), they all compressed about the same or harder than with 'Music light' values encoded in. On most DVD players I've encountered (but not on each one), there is the option to turn the DRC off. It will than disregard the DRC bitstream and play full dynamics irregardless of your setting.

The big problem is that end users almost never turn DRC off! And setting up playback with pink noise and an SPL meter...yeah, right.

[Sonsey@mac.com]

Originally Posted by kk@jamsync.com

The big problem is that end users almost never turn DRC off! And setting up playback with pink noise and an SPL meter...yeah, right.

"But it's set up at the factory!" - Direct quote from my brother in law, during a discussion about why my el-cheapo home surround system sounded better than his "top of the line" one.

[kk@jamsync.com]

Originally Posted by Sonsey@mac.com

"But it's set up at the factory!" - Direct quote from my brother in law, during a discussion about why my el-cheapo home surround system sounded better than his "top of the line" one.

I love walking into a setup where the people haven't torn off the plastic scratch covers on the stuff because they think it's part of the box! "But couldn't you see it looks kind of cloudy rather than shiny and new?..."

[vudoo]

Man ! this is confusing as the Compressor manual recommend '' None '' unless your mix is going to film.

I've tried none and Light Film setting, both sounded similar when played back...anyways, so i guess the consensus around here seems to be Light Music and Dialnorm -31 dbFS.

1-What happen if you have a 5.1 mix, Compressor manual recommend '' Standard Film '' setting for surround.

2- What's the difference between -27 dbFs and -31 dbFS setting for dialnorm

Thanks

[vudoo]

OK i guess i found the answer for question # 2, -27 dbfs dialnorm attenuates the signal ( dialog ) by 4 db and -31 dbfs leaves it intact, correct ??

[kk@jamsync.com]

Originally Posted by vudoo

OK i guess i found the answer for question # 2, -27 dbfs dialnorm attenuates the signal ( dialog ) by 4 db and -31 dbfs leaves it intact, correct ??

Correct.

As far as the Compressor manual, I haven't really looked at it because I've been encoding since the 569 and 562 came out (I had the first set in Nashville and wrote a review of them for Mix or AudioMedia...I forget). I *do* know that Apple's manual for Logic calls the divergence control "diversity", so I don't have a lot of respect for their manual writers these days.

As far as setting Dialnorm, if you're on your own, you're correct for the -31 dBFS setting, BUT if you have delivery specs for TV that mandate you set Dialnorm per the reading on the LM100 or Dolby Meter, then that's what you have to do. You don't really have a choice if you want to get paid!

[vudoo]

This is for DVD release and I'm also the one doing the DVD authoring.

I find that, in general, if the mix is well done, the difference between the various Compression settings is hardly noticeable.

As for having to mix to certain Dialnorm setting required by TV, i guess, it means one must use the LM100 or DMM. Is there an advantage in getting the LM100 hardware vs DMM, wich is quite a bit cheaper. Thanks

[kk@jamsync.com]

Originally Posted by vudoo

This is for DVD release and I'm also the one doing the DVD authoring.

I find that, in general, if the mix is well done, the difference between the various Compression settings is hardly noticeable.

As for having to mix to certain Dialnorm setting required by TV, i guess, it means one must use the LM100 or DMM. Is there an advantage in getting the LM100 hardware vs DMM, wich is quite a bit cheaper. Thanks

I bought the DMM. Also the older LM100s need to be upgraded to match current specs (ITU-R BS.1770-1).

[axisrecording]

Originally Posted by kk@jamsync.com

It depends. On some decoders, especially the more professional ones, you'll get
"none"...no change. However, I've had some experiences, especially with cheap DVD players, where the audio would get slammed and sound horrible.

So we are playing the odds here that it'll sound really bad if some cheap decks don't understand "none" or just a little bad on everything if I set it to "music light" I have a really hot mix to put to DVD. I'm guessing any compression at all won't be helpful. Anyone know what the ratio might be between players that understand "none" and those that don't? I can't decide if I should take the risk, and go with "none" or play it safe. hmmmm

[huub]

Originally Posted by axisrecording

So we are playing the odds here that it'll sound really bad if some cheap decks don't understand "none" or just a little bad on everything if I set it to "music light" I have a really hot mix to put to DVD. I'm guessing any compression at all won't be helpful. Anyone know what the ratio might be between players that understand "none" and those that don't? I can't decide if I should take the risk, and go with "none" or play it safe. hmmmm

Generally, for AC3 it's safer to not mix so hot, to make sure the dynamic range reduction doesn't kick in too bad.