PCM5.1 to 5.1 MP4 vs 640/448kbit Dolby

[jonathonsunshine]

Howdy yall, i have been messin around with a few blu-ray discs, and I was looking at standalone players, the PopCorn (a?)100 NMT and TViX a6500 (? I think that is the names ?) any how, I have come to the conclusion that NO standalone media player will have the flexibility or be as future proof as a computer so I'm not worried about doing anything to comply with standards.

Also, I have a fairly decent amplifier, 125w by 5 channels, it decodes dts and dolby digital but won't do any of the new formats on BluRay, ie, Uncompressed PCM or lossless DTS or Dolby True HD.

It does however have support for analogue passthrough.

So now I am thinking to convert the uncompressed PCM 5.1 to 5.1 mp4. So I encoded it with Nero AAC through MeGUI as VBR with .65 quality, the file ended up about 806kbits. My question is, do you think this would actually be of any benefit ? Is this actually worth while? Will it sound better than the 448 Dolby track? I'v heard that the rear channells in AAC don't come out that well, would I be better off using OGG ?

I guess I don't really have any question here,I am more interested in peoples general opinions / suggestions.

[EPiPH0NE]

IMHO for best results:

1) LPCM 5.1 -> 1536k DTS 5.1
2) LPCM 5.1 -> 768k DTS 5.1
3) LPCM 5.1 -> 640k AC3 5.1
4) LPCM 5.1 -> 448k AC3 5.1

I don't use AAC and wouldn't recommend it. You will get perfect quality/size ratio from the above with 1) sounding the best and 4) the worst for your AVR. But if the source is BluRay LPCM then even the 448k ac3 track will sound pretty nice. My 2 cents :)

[act.anon]

AAC is much more efficient than DTS or AC3; it 'achieves indistinguishable audio quality at data rates of 320 kbit/s (64kbit/s/channel) for five channels' versus transparency at 640kbit/s for AC3. DTS is even less efficient. AAC is also more flexible with regards to sample frequencies and channels. If I was reencoding to a lossy format, it would be AAC. But if you have a lossless stream to begin with, why not just compress it losslessly to FLAC @ ~1.5Mbit/s for 16-bit?

Vorbis is great too if you want to stick with FOSS.


See http://www.ebu.ch/CMSimages/en/tec_doc_t3324-2007_tcm6-53801.pdf