Is Circle Surround II compatible with Dolby Prologic II?

[adoniscik]

Can a DPLII-encoded stream be decoded using CSII?

[scharfis_brain]

yes .

[adoniscik]

I love brevity :)

Now for a more interesting question: what conditions must be met when encoding to (HE-)AAC with DPLII to preserve the multichannel information? Has anyone studied the relationship between the bit rate and multichannel fidelity?

[scharfis_brain]

don't use PS

[Rockaria]

The high-frequency signal components regenerated by SBR will also destroy the rear shifted phase info.
So we can say it depends on the fidelity we focus on : the overall quality(HE) or the channel seperation(LC) from 48kbps ~ . From 64kbps, I'd prefer HE-AAC for both fidelity. And from 128kbps, I'd prefer 5.1ch discrete HE-AAC.

Overall, HE-AAC will be better for overall fidelity and the seperation quality will increase as the bitrate goes higher(thus the SBR band freq. gets higher). Unfortunately, I don't have the 'SBR band frequency' table by bitrate allocation.;)

[shon3i]

don't use PS
Why when work so good


http://www.codingtechnologies.com/products/assets/PS_level1.gif

[scharfis_brain]

HE-AAC with 48 or 64 kbps leaves a pretty good amount of phase information intact.
PS doesn't leave enough phase information intact to rebuild a proper surround sound.

and please don't use marketing images to jugde audio quality. Use your ears.

[Rockaria]

I guess it's a good diagram for PS explanation;) but with DPL II encoding, it's another story.
As, iirc, the PS is based on the HE-AAC in another diagram(sorry I am lazy), thus taking the behavior I described above(even @ less than 48k), it also unrecoverabley merges the rear shifted phases, reproducing the broken monaural rears. I concluded it's completely NOT proper for DPL II encoding with some tests before.