stereo vs surround downmix with azid?

[Synth]

Whats the difference and which should I use for a 2\0 AC3 source?

[Slogra]

I would choose stereo.

When you use stereo the sound is directly converted to a stereo wav. So when the sound is stereo it will come out stereo. And when it's dolby surround it will be dolby surround.

But i'm not sure :rolleyes:

[MaTTeR]

2/0 is Dolby Pro Logic. If you have a 4, 5 or 6 speaker setup then downmixing to surround would be best, this keeps the DPL info. If you have 2 speakers then...well obviously stereo will work better for you:)

[DarkAvenger]

For a 2/0 source no downmix is needed...

[MaTTeR]

Originally posted by DarkAvenger
For a 2/0 source no downmix is needed...

Wouldn't you still set HeadAC3he to "Surround" mode though?

[DarkAvenger]

The setting shouldn't have any effect. It only has effect, when you donwmix x/y with y>0 to x/0.

[Northpack]

Is this for sure?

What about dynamic range compression on 2/0 Tracks? Isn't there already less DR than on a 5.1 track? So should DRC still be used for output channels?

[ChristianHJW]

DRC should be used in any case, at least a 'light' DRC .. even for 2 ch AC2 tracks ..

[DarkAvenger]

Sorry, but I think this is BS. Since no downmix is done, it is not really advised to use DRC for 2ch tracks. I guess these tracks are composed for DPL or stereo, so why would you degrade it furthermore? Of course, if you feel like needing more compression, go for it...

[ChristianHJW]

Sorry DA, i probably was missing something in the AC3 specs, but what has DRC to do with downmixing ?? :confused:

Performing DRC on an AC3 track AFAIK is done by reading the DRC tags attached to every block of data and process data accordingly .. i was not aware this process is bound to a 5.1 to stereo downmix in any respect ? Are you sure here ? Midas could best clarify i guess ...

[DarkAvenger]

Yes you are correct, but think over *why* DRC is used, then you'll understand my statement. Not everything which is possible is smart to be done...

[LigH]

This brings me to a possibly interesting idea: Is there any tool to display the DRC factor distribution over an AC3 file? I'd just like to know if e.g. all DRC factors for 2/0 AC3 files are tighter and for 3/2 instead wider spread. Then we can decide if it is useful to apply DRC on 2/0 audio by comparing the alternate 2/0 and 3/2 sounds of several movies.

In my opinion, DRC can be useful regardless of the audio channel format, e.g. to raise the overall loudness over the ambient noise floor (just one of the possible uses, as it is written in the audio driver setup of some DVD software players); in an ambience-isolated cinematic room with high average volume, DRC doesn't need to be applied - in your home's living room, near the street traffic, with just a HiFi set and limited maximum volume (you wouldn't want to disturb your neighbors), it is instead useful to use DRC.

Just because of this reason, I doubt that DRC is only related to the downmix type...

[ChristianHJW]

Well, in fact i was not aware there are any differences in DRC levels between 2/0 and 3/2 channel AC3s .... why should there be any ?

[pei]

I disturb my neighbors either way when I play a movie. :LOL:

I've been using a boost of 1.40 in HeadAC3he to get the quiet sounds where I want them, then the loud sounds are *too* loud. Where is this DRC option in HeadAC3he? Somewhere I overlooked I suppose...

Edit: OK I found the DRC options (I'm an idiot!!) I do agree that at least a light DRC should be used on 2/0.

[user]

You should differentiate between ordinary movies and concerts, music-movies eg. video-collections of musicians.

For movies DRC is necessary. Even "normal" (in azid/Headac3he/Besweet) DRC is often still too dynamically. The difference between talking scenes and action scenes, a lot exploding eg., is still very high, your neighbours will like it or not...

For music movies I do not recommend to use any DRC.
Not light, inverse, normal or heavy.....


I have had several examples with music. As 5.1 ac3, 2.0 ac3, or 48 kHz waves...

In each case the dynamics was well, no DRC needed.