Uncompressed PCM vs DTS MA vs DD HD vs ?? - AVS Forum
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post #1 of 20 Old 06-21-2007, 02:42 PM - Thread Starter
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Currently I have a PS3 sending audio (forget video for this discussion) to my Onkyo 805 receiver. The PS3 sends PCM (not bitstream). For Blu-Ray videos, I choose uncompressed PCM.

I believe this is the best sound quality available. However, most definitely worthy of a discussion.

Which format would you choose? And why is one better than another? (the DD vs DTS debate is an old one, so lets not get into that. probably should have titled it uncompressed pcm vs. DD/DTS).

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post #2 of 20 Old 06-21-2007, 03:12 PM
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I don't know the bit rates of all the formats, but would assume that would be the deciding factor.

One other thought would be which machine does the better job at decoding the audio file on the disk. By sending Linear PCM to your processor, the PS3 is doing the decoding. If you send your processor DD/HD or DTS-M, then the processor will do the decoding.

Is it 6 or half a dozen?? Hard to tell without listening.
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post #3 of 20 Old 06-21-2007, 04:17 PM
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Numerous discussions in the HD optical section discuss this very topic. Basically, all of the lossless formats (DTS HD MA, DTHD and LPCM) should be identical if the same master is used. The DTS and Dolby versions just use a smaller bit rate to achieve the final result.

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post #4 of 20 Old 10-21-2010, 12:28 AM
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Originally Posted by AV Doogie View Post

Numerous discussions in the HD optical section discuss this very topic. Basically, all of the lossless formats (DTS HD MA, DTHD and LPCM) should be identical if the same master is used. The DTS and Dolby versions just use a smaller bit rate to achieve the final result.

Wrong. Uncompress PCM is the original soundtrack. Anything else is compression. In the old days of Dolby Digital, I went through several center channel speakers, never happy with the boxed-in vocals. Well, after trying out my current center with a U-PCM, and then Dolby HD on the same movie, the U-PCM was natural, lifelike, and very CLEAR from the center. As for DTS variants, I havent tested but would expect the same. When in doubt, just buy the BD with Uncompressed PCM written on the back.
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post #5 of 20 Old 10-21-2010, 06:01 AM
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Originally Posted by pgdesigns View Post

Wrong. Uncompress PCM is the original soundtrack. Anything else is compression. In the old days of Dolby Digital, I went through several center channel speakers, never happy with the boxed-in vocals. Well, after trying out my current center with a U-PCM, and then Dolby HD on the same movie, the U-PCM was natural, lifelike, and very CLEAR from the center. As for DTS variants, I havent tested but would expect the same. When in doubt, just buy the BD with Uncompressed PCM written on the back.

It seems to be a mastering error when creating this disk. You do not believe how many disks are bad. I saw some even with channel assignment done wrong. TruHD and DTS MA should be as good as PCM - this type of compression is lossless, just like FLAC.
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post #6 of 20 Old 10-21-2010, 07:02 AM
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Originally Posted by pgdesigns View Post

Uncompress PCM is the original soundtrack. Anything else is compression.

Do you understand what lossless compression is (e.g., zipping a file)?

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post #7 of 20 Old 10-21-2010, 10:25 AM
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This has been gone over a few times. It comes down to this:

- Decoding from any format to LPCM must be done somewhere, the algorithm to decode is known, licensed, and should be identical between machines doing the decode. As such, it should not matter who does the decoding to LPCM with regards to sound quality.

- However, only the player has additional information to assist its mixing in extra content as it decodes to LPCM. So, if you want that content, you must decode in the player, since that meta-info isn't sent to the receiver and, therefore, is lost if you decode there.

- There is a set of people that insist the jitter on the HDMI line is sufficent to cause LPCM to sound worse than the encoded data. The claim is that when the data is decoded in the reciever there is less possibily for jitter to muck things up, as the receiver gets the encoded packets and must decode there. I suppose in theory this is possible, I don't entirely buy into it. I figure that if there were enough jitter to mess up the LPCM, it would mess up the encoded stream too and rather than get worse sound, you'd just get drop outs as the checksums on the encoded data (assuming there are checksums) wouldn't match and the receiver would throw them away. But, I haven't studied how the lossless codecs are transmitted through HDMI enough to know for sure...it'd be interesting to hear from someone who does.

Summary - your PS3 can decode just fine, why not let it. Further, you can get mixed in content by letting it decode that you can't if you decode in the receiver, so why decode there? It only has the possibility to have less information, and "no" possibility to have better sound or more information; so unless you just like to see the DD-HD or DTS-MA lights on your receiver, or your player can't decode one or the other to LPCM, I don't see a reason to send them to the receiver.
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post #8 of 20 Old 10-21-2010, 11:00 AM
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Quote:
Originally Posted by pgdesigns View Post

Wrong. Uncompress PCM is the original soundtrack. Anything else is compression. In the old days of Dolby Digital, I went through several center channel speakers, never happy with the boxed-in vocals. Well, after trying out my current center with a U-PCM, and then Dolby HD on the same movie, the U-PCM was natural, lifelike, and very CLEAR from the center. As for DTS variants, I havent tested but would expect the same. When in doubt, just buy the BD with Uncompressed PCM written on the back.


You need to review your understanding of the differences between lossless compression and PCM.

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post #9 of 20 Old 10-28-2010, 11:22 AM
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quick question folks. I have Dave Matthews/Tim Reynolds Live at Radio City bluray. I have 3 choices for the audio, 2 channel PCM, forgot the other one, and 5.1 96/48 khz. They all sound really good. However, why is 2 channel PCM louder?

Any help would be greatly appreciated.
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post #10 of 20 Old 10-28-2010, 11:47 AM
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^^^

likely because it's hotter than the other tracks...

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post #11 of 20 Old 10-28-2010, 05:46 PM
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Originally Posted by ccotenj View Post

^^^

likely because it's hotter than the other tracks...

Yes by hotter it has a higher bitrate. DTS blows away Dolby digital. The 2Channel is probably 96/24 KhZ. That's why it probably seems louder.
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post #12 of 20 Old 10-28-2010, 05:53 PM
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^^^

no. bitrate has zero to do with it.

dts doesn't "blow away" dolby digital... but many people think it does, again, because many dts tracks were hotter than dd tracks... besides the fact that it's not germane to the discussion in any way...

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post #13 of 20 Old 10-29-2010, 01:44 PM
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Not to mention that they're different codecs too. Comparison solely by bitrate is crude at best.
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post #14 of 20 Old 10-29-2010, 03:24 PM
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Originally Posted by krabapple View Post

Not to mention that they're different codecs too. Comparison solely by bitrate is crude at best.

You are saying comparison at bit rate is crude at best? The bit rate most defiantly will have say in the quality of the decoding. Hence "Hotter"
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post #15 of 20 Old 10-29-2010, 03:25 PM
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^^^

you have NO idea what you are talking about...

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post #16 of 20 Old 10-29-2010, 03:28 PM
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Originally Posted by krabapple View Post

Not to mention that they're different codecs too. Comparison solely by bitrate is crude at best.

As far ad DTS It's a shame back when DVDs had DTS encoded that people didn't even know what DTS let alone the fact that the DVD they were watching even had DTS on it. I can't find DTS encoded DVD's anymore. I would take DTS over Dolby. Just my opinion.
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post #17 of 20 Old 10-29-2010, 05:15 PM
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Originally Posted by godfromthesnake View Post

I would take DTS over Dolby. Just my opinion.

From the intial post:
(the DD vs DTS debate is an old one, so lets not get into that.)
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post #18 of 20 Old 10-29-2010, 05:24 PM
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Quote:
Originally Posted by godfromthesnake View Post

You are saying comparison at bit rate is crude at best? The bit rate most defiantly will have say in the quality of the decoding. Hence "Hotter"

HOtter is louder. Bitrate has zip to do with how loud the sound is encoded. You can say with some degree of certainty that DD encoded at a higher bitrate than another DD encode of the same material will sound better, but it won't be louder. Because DTS and DD do the "losing" part differently, you cannot directly compare the bitrate of a lossy DTS with the bitrate of a lossy DD track and say which will be better fidelity. The argument is often made, in effect, that DD can capture exactly the same amount of sonic information using fewer bits than DTS. IIRC, controlled testing has in general confirmed this.

Moreover, because DTS does not utilize its dialnorm function, almost always a movie will sound louder in DTS than in DD, unless you adjust volume to account for the dialnorm offset of the DD. There's also at least speculation that some DTS tracks are actually encoded with a higher average loudness to begin with than DD. IDK if that's proven, and its sure to vary from movie to movie anyway. If you have a choice, choose what you want. If you don't have a choice, in my view, don't let fretting over which codec was used, or what bitrate was used for the particular codec, overwhelm your ability to enjoy the movie. Even the lower bitrate DD and DTS on DVDs sounds quite decent, especially considering how much data they toss out.
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post #19 of 20 Old 10-30-2010, 01:56 PM
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Originally Posted by godfromthesnake View Post

... DTS blows away Dolby digital. The 2Channel is probably 96/24 KhZ. That's why it probably seems louder.

It's common for neophytes to mistake loudness for better sq. It's what drives the CD market.

In a level matched comparrison with standard DVD's, you couldn't tell the difference and to make that claim about lossless shows no knowledge of what lossless actually is.

J Dunlavy:.. if you stop to think about it, no loudspeaker can sound more accurate than it measures ...
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post #20 of 20 Old 10-30-2010, 07:25 PM
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Originally Posted by htcritic View Post


It's common for neophytes to mistake loudness for better sq. It's what drives the CD market.

In a level matched comparrison with standard DVD's, you couldn't tell the difference and to make that claim about lossless shows no knowledge of what lossless actually is.

Question... Wouldn't a higher bit rate mean instruments/movies ( if recorded properly) have a more bold sound thus feeling fuller which some might confuse with louder?

I would think it's like low bit rate mp3. It just doesn't have the sound thickness therefore sounding "quitter"
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