IPB

Welcome Guest ( Log In | Register )

PNS and M/S coding
sana.iitkgp
post Oct 5 2012, 07:09
Post #1





Group: Banned
Posts: 10
Joined: 5-October 12
Member No.: 103640



From the specifications of AAC

In M/S coding section

Please note that ms_used[][] is also used in the context of intensity stereo coding and perceptual noise substitution. If intensity
stereo coding or noise substitution is on for a particular scalefactor band, no M/S stereo decoding is carried out.


In PNS section

If the same scalefactor band and group is coded by perceptual noise substitution in both channels of a channel pair, the correlation of the noise signal can be controlled by means of the ms_used field: While the default noise generation process works independently for each channel (separate generation of random vectors), the same random vector is used for both channels if ms_used[] is set for a particular scalefactor band and group. In this case, no M/S stereo coding is carried out (because M/S stereo coding and noise substitution coding are mutually exclusive). If the same scalefactor band and group is coded by perceptual noise substitution in only one channel of a channel pair the setting of ms_used[] is not evaluated.


I'm confused after reading both these. If only one channel has PNS data and if MS coding is on for that particular scalefactor band. Do we need to proceed with M/S coding or skip M/S coding for that scalefactor band?
Go to the top of the page
+Quote Post
 
Start new topic
Replies
C.R.Helmrich
post Oct 8 2012, 10:37
Post #2





Group: Developer
Posts: 690
Joined: 6-December 08
From: Erlangen Germany
Member No.: 64012



QUOTE (sana.iitkgp @ Oct 5 2012, 08:09) *
I'm confused after reading both these. If only one channel has PNS data and if MS coding is on for that particular scalefactor band. Do we need to proceed with M/S coding or skip M/S coding for that scalefactor band?

I'm confused, too. If you're building an encoder, I think you should avoid having PNS in only one channel-SFB of a channel pair element. Either in the same SFB in both channels, or in none. My guess is that you should assume that M/S decoding is skipped, but I'll double-check.

Chris

This post has been edited by C.R.Helmrich: Oct 8 2012, 10:39


--------------------
If I don't reply to your reply, it means I agree with you.
Go to the top of the page
+Quote Post

Posts in this topic


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 25th November 2014 - 23:30