Originally Posted by PlayNice
I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?
PCM 21.5Mbps VBR does not occur in real because:
1. PCM is CBR.
2. PCM 7.1 24/96 is 18.43Mbps (8*24000*96)
3. PCM 5.1 24/192 is 27.64Mbps (6*24000*192)
Take two real examples both with all three PCM, dts-HD MA and Dolby TH tracks and you see typically dts and Dolby achieve nearly 50% compression or more:
Red Cliff BD (HK):
dts-HD MA 2587kbps
Dolby TH 1996kbps
Divertimento audio BD (no BD info but player info display):
PCM 5.1 24/192 CBR: 27.64Mbps
dts-HD MA 13-15Mbps VBR
Dolby TH: 12-14Mbps VBR
You're very unlikely to see dts-HD MA or Dolby TH at higher bit-rates than this for BD. For movie BDs at 48kHz sample rate the typical bitrates for dts and Dolby are much lower. Plenty of examples in the Audio and Video Spec thread in the BD Software forum. The info has been there for a long time if only you look for it.