Difference between Dolby Digital and DTS - AVS Forum

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Rixxell Stryfe's Avatar Rixxell Stryfe
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post #1 of 15
02-17-2010 | Posts: 3
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Hi I have a Logitech Z5500 Digital system that I've had for almost a year and a half. I was wondering what is the difference between the two.
rdgrimes's Avatar rdgrimes
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02-17-2010 | Posts: 16,462
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"difference" in what sense?
Rixxell Stryfe's Avatar Rixxell Stryfe
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post #3 of 15
02-17-2010 | Posts: 3
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Difference as in they both output 5.1, but is there anything as in sound quality that would make me want DTS over DD for movies. I mean some DVDs have DTS tracks but what makes it special. I just don't understand why some movies have it but not all come with them.
rdgrimes's Avatar rdgrimes
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02-17-2010 | Posts: 16,462
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At one time, DTS decoders in AVRs were not as common as DD, and DTS licensing cost more per disc. So it was seen less and still is for DVD.

They are very different codecs, DD uses more compression but is also a more efficient compressor. DD on DVD tends to be 448Kb, DTS on DVD can be 784Kb or 1.5Mb. It's long been a hot topic of debate which one "sounds better", but DTS seems to have the edge in popularity for quality. Unless you are comparing the same title with both codecs, it's not much of a comparison and winds up being a popularity contest more than a true comparison. DTS tends to have higher volume levels than DD, which also greatly impacts perception of quality. When DTS first came out for movies, DD was still a matrixed multichannel codec where DTS was discrete. those differences are no longer relevant.

Let your ears be the judge.

Dolby TruHD and DTS-MA produce identical results on BD movies.
Rixxell Stryfe's Avatar Rixxell Stryfe
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02-17-2010 | Posts: 3
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Thank You for your reply, I've noticed the volume difference in the separate tracks and I was just wondering why that was so.
sdurani's Avatar sdurani
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02-17-2010 | Posts: 19,880
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Quote:
Originally Posted by rdgrimes View Post

When DTS first came out for movies, DD was still a matrixed multichannel codec where DTS was discrete.

By "movies", do you mean commercial cinema or home video? In either case:

DTS first came out theatrically in 1993 (Jurassic Park). DD had already come out a year earlier (Batman Returns) as discrete 5.1, not matrixed multi-channel.

DTS first came out on laserdisc in 1997 (again, Jurassic Park). DD had already come out two years earlier (Clear & Present Danger and True Lies) as discrete 5.1, not matrixed multi-channel.
SiriuslyCold's Avatar SiriuslyCold
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post #7 of 15
02-17-2010 | Posts: 2,745
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this is an age old question. Someone on HTF did a scientific comparison years ago you can read about it there - Roogs Benoit's DD/DTS test


jpjibberjabber's Avatar jpjibberjabber
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02-25-2010 | Posts: 803
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welcome to 1997
thehun's Avatar thehun
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post #9 of 15
02-26-2010 | Posts: 7,338
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Quote:
Originally Posted by Rixxell Stryfe View Post

I mean some DVDs have DTS tracks but what makes it special. I just don't understand why some movies have it but not all come with them.

Marketing. Some studios used DTS as an "added value content" to boost sales on certain titles.
Feirstein's Avatar Feirstein
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03-24-2010 | Posts: 387
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When the HDTV standard was being set in mandated that the audio standard meet certain standards such as speech normalization. Only Dolby Digital submitted a proposed audio system that met that mandate.

When audio was being selected for analog stereo TV, Dolby Labs submitted a proposed standard with the industry desired speech normaliztion.

When multi-channel was proposed for DVD's Dolby Labs provided speech normalization, as requested by the standard, and a standard for bass levels; DTS submitted a proposed system without speech normalization and with a different spec (louder) for the bass level in the sub channel.

Thus when playing back a DVD's or Blue Rays Dolby audio track, unless the receiver was/is properly calibrated for both systems (not always the case) the DTS tracks provided louder (improperly calibrated) bass. And the DTS tracks lacked speech normalization. This was the major reason why one sounded significantly different than the other. Typicall the Dolby tracks were more accurate, but not always favored by the listner or reviewer often ignorant of these technical differences.

Also, most Dolby Digital DVD tracks were mastered at its maximum sampling rate, while few if any DTS tracks were mastered at that systems maximum sampling rate due to storage room constraints on DVD's. Confused yet?
BIslander's Avatar BIslander
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03-24-2010 | Posts: 8,593
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Quote:
Originally Posted by Feirstein View Post

When the HDTV standard was being set in mandated that the audio standard meet certain standards such as speech normalization. Only Dolby Digital submitted a proposed audio system that met that mandate.

When audio was being selected for analog stereo TV, Dolby Labs submitted a proposed standard with the industry desired speech normaliztion.

When multi-channel was proposed for DVD's Dolby Labs provided speech normalization, as requested by the standard, and a standard for bass levels; DTS submitted a proposed system without speech normalization and with a different spec (louder) for the bass level in the sub channel.

Thus when playing back a DVD's or Blue Rays Dolby audio track, unless the receiver was/is properly calibrated for both systems (not always the case) the DTS tracks provided louder (improperly calibrated) bass. And the DTS tracks lacked speech normalization. This was the major reason why one sounded significantly different than the other. Typicall the Dolby tracks were more accurate, but not always favored by the listner or reviewer often ignorant of these technical differences.

Also, most Dolby Digital DVD tracks were mastered at its maximum sampling rate, while few if any DTS tracks were mastered at that systems maximum sampling rate due to storage room constraints on DVD's. Confused yet?

A lot of history there. I believe DTS fell into line on the LFE issue quite early on. So, there's no current difference between the two on that front. The use of dialog normalization remains a point of differentiation. DD 5.1 uses dialnorm, DTS Surround does not. And the Dolby implementation means most DTS tracks are a bit louder. But, DTS included dialnorm with its lossless Master Audio codec.

As for sampling rates, DD 5.1 is never encoded at the maximum 640 kbps rate on DVD since the DVD standard limits it to 448 and it is often less than that in practice. DTS is generally encoded at 754, half the maximum rate of 1509.
Sitting Bull's Avatar Sitting Bull
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03-24-2010 | Posts: 449
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Quote:
Originally Posted by BIslander View Post

As for sampling rates, DD 5.1 is never encoded at the maximum 640 kbps rate on DVD since the DVD standard limits it to 448 and it is often less than that in practice. DTS is generally encoded at 754, half the maximum rate of 1509.

Actually, Pink Floyd's "Pulse" concert DVD uses DD 5.1 in both 448 and 640 kbs. There are likely other DVDs that do the same, though I am unaware of them.
BIslander's Avatar BIslander
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Quote:
Originally Posted by Sitting Bull View Post

Actually, Pink Floyd's "Pulse" concert DVD uses DD 5.1 in both 448 and 640 kbs. There are likely other DVDs that do the same, though I am unaware of them.

That's the only one that I've ever seen. And, I think it was only the initial release.
sdurani's Avatar sdurani
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03-25-2010 | Posts: 19,880
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Quote:
Originally Posted by Feirstein View Post

DTS submitted a proposed system without speech normalization and with a different spec (louder) for the bass level in the sub channel.

Not sure what you mean by "speech normalization", but DialNorm is an overall volume offset intended to keep average dialogue levels roughly the same from program to program. Also, I have trouble believing that DTS would submit a spec that admitted to deliberately changing the bass level during encoding. Compression codecs attempt to stay as faithful to the original as possible, not re-mix the sound for louder bass.
Quote:


Thus when playing back a DVD's or Blue Rays Dolby audio track, unless the receiver was/is properly calibrated for both systems (not always the case) the DTS tracks provided louder (improperly calibrated) bass.

IF the Dolby track has DialNorm, it will play back softer (typically 4dB lower) than the DTS track. But that doesn't mean the DTS track will provide "louder (improperly calibrated) bass". The low frequencies will remain proportional to the rest of the soundtrack, irrespective of volume level.
thehun's Avatar thehun
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post #15 of 15
03-29-2010 | Posts: 7,338
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Quote:
Originally Posted by BIslander View Post

That's the only one that I've ever seen. And, I think it was only the initial release.


"DVD Spectacular" was released in 1997 by Delos and Dolby had the first 640kbps "hidden" DD track of the "1812 Overture"
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