Do I need to back up both 2ch and 6ch AC3?

[Heff]

Some movies have both a 2 channel and 6 channel AC3 tracks. Do I need to back up both? Does 6ch AC3 do everything 2ch AC3 does in a 2channel playback enviroment, or do I need the 2ch track for that? TIA

[jimmalenko]

I'm pretty sure that the 6 channel AC3 is downmixed to stereo (2 channel) if you just have a stereo output (be it the TV speakers, or any other non-5.1-capable sound system).

[Heff]

So I guess the smart move is to just included the AC3 6ch track and nothing else.

[redwudz]

So I guess the smart move is to just included the AC3 6ch track and nothing else.

That's what I do. Especially if you need the space.

[Bodyslide]

Yes, just take the AC3 6 ch track and your system will down sample to 2 ch.

[wulf109]

The average movie uses 400MB's for a 6 channel audio,the 2 channel will be about 180MB's. Using the 2 channel allows you to put another 220MB's into the all important video stream. I would opt for the 2 channel audio.

[johns0]

2 channel ac3 might be directors comments so if you select that play it first before you burn.

[Gurm]

IF the movie has both, you can pick whichever you like. The 6-channel will almost always be the default, and I'd stick with that especially if you want the option of having surround-sound at some later date.

Plus, as johns0 said, many movies don't have an actual 2-channel mix of the main movie ANYWAY - just director's comments and such.

[ghoster]

The average movie uses 400MB's for a 6 channel audio,the 2 channel will be about 180MB's. Using the 2 channel allows you to put another 220MB's into the all important video stream. I would opt for the 2 channel audio.

yep if there is a 2 channel audio track availble i always go with that if the movie requires compression.....

[mattyboy]

The 2 channel is often only like 8MB or so anyway though.

[iooi]

2 channel ac3 might be directors comments so if you select that play it first before you burn.

Wise move there, have been a couple of moives i have backed up lately (wrong turn, hellboy) where the 6 channel audio is the main film soundtrack.....
Removed then at great cost...

[guns1inger]

The difference between 2 channel and 5.1 channel doesn't make enough difference to the video quality to justify throwing away all that lovely surround goodness. Sometimes I even keep the commentary as well - although I often use DVD-RB instead of shrink.

[Gurm]

The 2 channel is often only like 8MB or so anyway though.

You meant to add about 172MB to that, right?

[mattyboy]

No

[Gurm]

You wrote:

"The 2 channel is often only like 8MB or so..."

Since it's usually around 180MB, your number is a LITTLE off, don'tcha think? Hmm?

[jimmalenko]

I'm with Gurm on this one

If we're talking for the main movie (which I assumed we are), then 192kbps (normal AC3 2-channel bitrate) for say, a 120 minute movie is about 169MB by my calculations

[stiltman]

I always wondered the same thing. So if I remove 2 channel stereo and only have 5.1, most/all DVD players will automatically down sample to 2 channel stereo if 5.1 is not supported?

I know it doesn't work like this with DTS. I have a few DVDs that only have DTS on them and I can't hear the sound (I have to redo them when I get a chance) as my new apex doesn't support DTS and my old Panny did

[canadateck]

I always wondered the same thing. So if I remove 2 channel stereo and only have 5.1, most/all DVD players will automatically down sample to 2 channel stereo if 5.1 is not supported?

Yes.

[mattyboy]

I'm with Gurm on this one

If we're talking for the main movie (which I assumed we are), then 192kbps (normal AC3 2-channel bitrate) for say, a 120 minute movie is about 169MB by my calculations

You're right. I was thinking of the sub picture size. My bad! Its late thats all.

[MOVIEGEEK]

If you don't have a 5.1ch HT system why use 5.1ch audio?If you listen through tv or stereo use 2ch.

[lordsmurf]

If you don't have a 5.1ch HT system why use 5.1ch audio?If you listen through tv or stereo use 2ch.

I keep it because I keep telling myself "someday I'll buy myself a nice big surround sound system".

[jimmalenko]

If you don't have a 5.1ch HT system why use 5.1ch audio?If you listen through tv or stereo use 2ch.

I keep it because I keep telling myself "someday I'll buy myself a nice big surround sound system".

I was the same ... until my future father-in-law bought us a Yamaha 6.1 channel surround sound system as an engagement present

Now I'm quite happy I kept the 5.1 channel for the backups, although it shouldn't really be that much of a hassle for those who have made 2 channel backups to just make another backup, this time with the 6 channel

[mats.hogberg]

Of course, keep the 5.1 audio. Like everyone else, while you've only got a stereo system today, it's only a matter of "when", not "if" you're going to buy that surround system.
Only real argument for not selecting the 5.1 audio, is that you get less space for video, But: Try ripping 2 versions - one with only 2 channel audio, one with 5.1 audio. Rest of the disk goes to video. Do you really think you can spot which is which (without listening to it!)?

/Mats

[adam]

As for why DVDs even have both 6 and 2 channel sources for the same audio track, its because the quality of the downmix will vary drastically from one playback device to another. For example, if your player/receiver doesn't have a dialog normalization option then the 6 channel track played in stereo will be overall very quiet, but the voices will be too quiet and the sound effects will be too loud. You'll find yourself adjusting the volume from scene to scene, and definitely if you jump between the movie and the other features on the disk.

A studio downmixed 2.0 track won't have these problems.

[ghoster]

normally i select the 5.1 channel, but if by choosing the 2 channel audio track the video stays at 100% i will go with that all the time instead of compressing the video to keep the 5.1 audio track........

[Gurm]

ghoster,

You're pretty much alone, pal. Half the movie experience for me is the surround sound - and for many others as well. If I didn't want surround sound, I'd still be watching VHS.