Thread: Question about Downmix

Posts: 4

Post by dead_man_surfing January 29, 2006 (1 of 4)
When people talk about the Downmix, do they talk about the CD - layer ? And why do many think that those Dowmixes arent good ?

D.

Post by raffells January 29, 2006 (2 of 4)
dead_man_surfing said:

When people talk about the Downmix, do they talk about the CD - layer ? And why do many think that those Dowmixes arent good ?

D.

Generally when people refer to Downmix ,it is the 5.1 channels down to 2 channel stereo.done usually by playback unit.This by its very nature has to be a compromise.You can work out several reasons why...phase is a major factor..
I have also read people refer to the CD mix being created from a higher rez original source as Downmix incorrectly..
This is problamatical due to the various ways (alogrithms) that convert 48hz (96hz) sampling down to 44.1 and which of the extra bits get truncated...
Dave

Post by dvda-sacd February 1, 2006 (3 of 4)
raffells said:

This is problematical due to the various ways (alogrithms) that convert 48hz (96hz) sampling down to 44.1 and which of the extra bits get truncated...

That is to say: DOWNSAMPLING.

Post by mdt February 1, 2006 (4 of 4)
dead_man_surfing said:

When people talk about the Downmix, do they talk about the CD - layer ? And why do many think that those Dowmixes arent good ?

D.

It can mean different things. During production of the record, downmix means the process of mixing the microphone signals captured seperately on the orignal multitrack to the channels of the target format, be this stereo, 5.1 or anything in between, depending on what the mic-set up was intended for.
With a mch DVD-A, downmix can mean the player automatically down-mixing the multichannel track to stereo during playback, if the disc doesn't have a dedicated stereo track. Its probably this form of downmix of which you heard it was no good, it does not exist with SA-CD.
In any case downmix has nothing to do with the CD layer (except for the downmix on the recording side, see above)Deriving the CD layer from the high-res layer is called down-conversion or down-sampling. By the way, the CD layer exists only on SA-CD which doesnt ever use downmix on playback.

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