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Originally Posted by Shadowman82
With people having had some time now to experience the different Audio formats commonly found on Blu-ray discs ( PCM , Dolby DigitalTrue HD, dts-hdma) did any of these turn out to sound better than the others or are they all equally good ?
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Remeber with PCM, Dolby TrueHD, and DTS-HDMA we are comparing the mastering/mixing and not the codecs themselves. For the actual codecs all three have exactly the same mathematical output; however it is possible that a soundtrack may be "sweetened" for prior to encoding for one codec and not another.
I believe DTS still does a lot of encoding in-house and I believe they feel that "sweetening" is part of getting the home experience right. IIRC their encoders have different presets based on the type of movie being encoded and I believe the master is EQ'd differently prior to encoding in order to give the best home experience. Also since DTS does a lot in-house you have talented people very familiar and experienced with encoding/mixing/mastering for the home. DTS also has the alternate surround speaker configurations for 7.1 (again often used for straying from the theatrical masters to enhance the home experience), and less support for lossless decoding in hardware due to needing large amounts of DSP processing power. Finally when contracted for an encode DTS will often go above and beyond the typical studio effort to ensure they have the best master that exists for a given title, which is something to be considered. Not all DTS encodings are done in-house anymore, though, so these statements don't always apply.
Dolby TrueHD is primarily encoded by the authoring house or studio, so in these cases you may have less experienced people or people whose job it is to just encode the master attenuated for home levels - so you might have soundtracks with less "pop" when mastered in TrueHD simply because you don't have top-notch experienced DTS-employed mixers doing the mastering prior to encoding. Also, some complain that the Dialog Normalization feature of Dolby TrueHD theoretically harms the signal; personally I think that is a bunch of baloney because any cheap crappy PC software can do the manips that DialNorm does without any significant quality loss. But if you are over-analyzing you could consider that, I guess. This has a ton of support in hardware.
PCM is similar to TrueHD, except it requires even less skill so you could probably get away with doing a simple home attenuation EQ - no real encoding required here. One disadvantage to PCM is that it is not packeted and if it is stored on a hard drive that has some bad sectors somewhere on the way to getting on the Blu-ray Disc you will hear snap/crackle/pop on the soundtrack (like Unbreakable). On TrueHD/DTS-HDMA bad sectors are much less of a problem because they would either be able to be corrected w/ error correction or you would get a dropout. A dropout is a lot easier to detect in QA than a few snap/crackle/pops as would be the case with PCM. Again, PCM is widely supported in hardware.
"Which sounds best" really depends on your definition of "best," and you must remember you are only comparing the typical mastering/mixing process prior to encoding in each codec, not the actual codec itself since all the codecs output the same thing. Some people feel they should get the theatrical master, period - attenuated for home levels and no other changes. That is not a bad viewpoint but one must consider that the acoustics of the home environment are far different than a theater.
A better question for what you are trying to ask would be, "whose typical pre-encoding mixing/mastering process do you prefer?"
But, if you were to ask me in terms of codeec which I think is the best, I would go with Dolby TrueHD. All three codecs sound exactly the same (mathematically identical output), so asking which sounds best is not useful. However, Dolby TrueHD takes much less processing power than DTS-HDMA and as a result has far superior support in hardware. And, it is much more efficient than PCM while retaining mathematically identical sound input.
So, given an identical mastering & mixing job with no pre-encoding EQ applied, TrueHD would be my choice since it offers mathematically identical sound quality (exact same output bits) to the other two options while using much less processing power than DTS-HDMA and much less space/bandwidth than PCM.