hy all

a few days i see 2 posts of Jell with some like this:
when i encode using dual channel,i have problems(noises?)
in my prologic player....(something like this).

then i search and read tons and some explanations
was not clear about the differences between stereo and dual channel.

my conclusion ...
and maybe this is the reason of Jell problems with dual channel...

examples using 128 bitrate:

stereo:
128 for the 2 channels of audio!
when one side of the channels need more bitrate then another,
this side will got more bitrate!
example:
if in the right channel have more sound that the left in one moment,
will be used more bitrate for the right and less for the left,
then the side that need more bitrate will got it.

dual channel:
128 for the 2 channels of audio, 64 for the right and 64 for the left!
when one side of the channels need more bitrate then another,
this side will got only 64....is his part!
the other side will use the another 64 for less sound.
if the right channel have more sound that the left in one moment,
he have 64 (his part) for the right and 64 for the left,
then the side that need more bitrate will got
the middle of the bitrate choosed,
no matter how more bitrate this side need
and the another side have to encode less sound.



STEREO have the bitrate in the center of the audio,
giving more bitrate to the channel that need more bitrate!

DUAL CHANNEL have middle bitrate for each channel,
no matter how channel need more or less bitrate.

my simple conclusion:
....STEREO is the better choice!


all opinions and hints are welcome as always!

yeah Avalon ,
i was one that wrote to you change your guide in few days.
please,don't do that!

let your guide using STEREO.

i have extreme atention with audio too.
now my choice is encode the movies in 2 cds
to got better image and with better audio too!

using 2 cds we got high resolutions and
224 bitrate or more for audio (48k)!
the general result is amazing!

No Jorel, this is the definition of Joint Stereo.

The diff between dual channel and Stereo isn't there. It is in the application of the psycho-acoustic correction.

In dual channel, the psycho-acoustic is applied on each channel separately (or perhaps even, not applied at all because normaly psycho-acoustic is related to stereo sound, and in dual chanel with have in fact two mono sounds). That's why dual chanel gives better result for surround sound (psycho accoustic correction modified the surround part of the stream).

ok Phil,
very clear about join-stereo...i have some more doubts!


like you wrote about dual channel:
"and in dual chanel with have in fact two mono sounds"

well,if dual channel have 2 mono(sound) tracks,
means 64 for each channel using 128 bitrate,
the "problem" remains like i wrote:
"have 64 (his part) for the right and 64 for the left,
then the side that need more bitrate will got
the middle of the bitrate choosed,
no matter how more bitrate this side need
and the another side have to encode less sound."

for this reason i post:
" i search and read tons and some explanations
was not clear
about the differences between stereo and dual channel."

i need more details cos in "everywhere" is not clear!

If you are encoding at 128Kbps, either stereo or dual channel, each channel has a bitrate of 64Kbps. In stereo, if one channel doesn't require much bitrate, then the other channel can raise "borrow" bitrate from the other channel. In practice, both channels are almost balanced most of the time. So there's not that much advantage of using stereo over dual channel. As a matter of fact, stereo, with it's variations, will sometimes mess up surround signals on a Prologic receiver ( I have that problem! ) so it's best to use dual channel if you are encoding surround 2 audio.

-kwag

now is very clear!

"it's best to use dual channel if you are encoding surround 2 audio."

thanks, this was great!

I'm trying to convert a Divx file to KDVD. This is what it says in AVIcodec program for the audio stream, Audio : 26 MB, 170 Kbps, 48000 Hz, 2 channels, 0x55 = MPEG Layer-3. Since it says 2 channel but not surround, do I convert it to Stereo or Dual Channel MPEG-2 audio? I have been using Stereo but not sure if I should have used Dual Channel instead.

It's ALWAYS say 2channels. You never have any mention of surround because there is no way to find is a stereo sound contains a surround channel or not. Only your hears can do that when you turn on the surround decoder of your receiver : if the sound seems correct, there is a surround channel

This time the humain brain is still better than the machines

great link with big details....thanks to onyx:


http://www.modatic.net/audio/glossary.php