(AC32.0)-[VS]-(AC35.1)

[XGeo]

hello !
I want to know if a 192Kbps AC3 2.0 has better quality then a 192kbps AC3 5.1

thanx for your answer

[yoda313]

Hello,

Not quality, QUANTITY!

The only difference is MULTICHANNEL sound. That's the main reason for digital audio. Front left, center, Front Right, Rear Right, Rear Left, LFE (sub channel).

Kevin

[BJ_M]

yes it would because a 5.1 192kbps bit rate file would be horribly low bit rate per channel

[yoda313]

Hello,

would be horribly low bit rate per channel

Well I don't know how horrible it would be. If you take the lowest main bit rate of 384 for dolby 192 is half of 384. Where you'd get that low of a 5.1 bitrate I don't know (trailer maybe???). I wouldn't think it would sound THAT bad.

Kevin

[Heywould3]

that is a low BR for ac3.. but as stated the quality of either would be the same just one would use more channels. it would also have a much larger file size
As yoda said.. multi channels are the difference.. AC3 2.0 is front left and front right only. where AC3 5.1 is front right front left center LFE and rear left and right.. all the sound at your mentioned bitrate would be teh same for each speaker just more speakers.

Clear ?

[BJ_M]

Hello,

would be horribly low bit rate per channel

Well I don't know how horrible it would be. If you take the lowest main bit rate of 384 for dolby 192 is half of 384. Where you'd get that low of a 5.1 bitrate I don't know (trailer maybe???). I wouldn't think it would sound THAT bad.

Kevin

192 / 5 = 38.4 per channel

[XGeo]

So a 2.0 Ac3 @ 192k will have a left 96kbps channel and a right 96kbps channel ?

conclusion: when lowering the audio channel of a 448 Ac3 5.1 audiotrack...the best choice is AC3 2.0.

thanx ppl

[Gurm]

So a 2.0 Ac3 @ 192k will have a left 96kbps channel and a right 96kbps channel ?

It's not quite that simple but sort of, yes. (There's interpolation, etc.)

conclusion: when lowering the audio channel of a 448 Ac3 5.1 audiotrack...the best choice is AC3 2.0.

No no, not necessarily. Given the constraints that you placed forth at the beginning of this thread, you are correct - 192KBps AC3 5.1 would be roughly 2/5 the bitrate per channel of 192KBps AC3 2.0, however in general they would sound the same because nobody would actually author AC3 5.1 at 192KBps.

What are you using to alter the AC3 structure in this manner anyway?

[soloredd]

Sorry to thread hi-jack but this might come into question for some other readers as well...

Is there a negative impact on using only 5.1 AC3 when watching a DVD on a TV with only 2 speakers? Will the sound be affected? Or are all of the channels just be combined to be fed through the 2 speakers in the TV?

[BJ_M]

they can be -- sometimes the combining of channels electrically can cause phase cancellation and combing effects ... if you only have 2ch , use 2ch ac3 if you can ..

this is not always the case - but can happen ..

i have seen commercial dvd's with a channel out of phase even ..

[Martyn1980]

Just done some tests and a 192 5.1 AC3 does sound very rough, though it depends on how fussy you are, encode an mp3 to 64kbps stereo and if that sounds OK for you then this probabaly would too.

If you wanted a low bitrate surround track, a 192 2.0 AC3 encoded to DPL2 sounds much better.

[yoda313]

Just done some tests and a 192 5.1 AC3 does sound very rough, though it depends on how fussy you are, encode an mp3 to 64kbps stereo and if that sounds OK for you then this probabaly would too.

If you wanted a low bitrate surround track, a 192 2.0 AC3 encoded to DPL2 sounds much better.

Hello,

Just to translate I believe Martyn1980 is saying DPL2 is Dolby Pro Logic 2 (the format that creates virtual 5.1 from any stereo source) FYI.

Kevin

[Martyn1980]

LOL, yes i was meaning DolbyProLogic2, im just a lazy typer at times.

[XGeo]

Ok thanx ppl my conclusions are done !