Are DTS & Dolby Digital "lossy" formats?

[kexodusc]

Obviously I'm looking for a quick answer or I would have spent more time looking this up...gonna be on the road the next few days with limited web-browsing time...

So:
Are these "lossy" formats in the same way MP3 and WMA files are lossy, or is there some other form of compression or something going on...
Thanks.

[N. Abstentia]

I'm pretty sure they are, but not in the same way as MP3 and WMA. DTS is far less lossy than DD, as it can have over twice the bitrate which is why it can sound much better than DD (if it's done right).

In fact now that I think about it, they have to be lossy formats, otherwise there would be no need to move from DTS CD's to lossless formats like MLP and DSD that are used for DVD-A and SACD.

[kexodusc]

I guess it probably depends on how you define "lossy"...
Encoding doesn't necessarily mean loss...and compression could allow for smaller files without loss of information, though I agree with you, a properly done DTS track is usually better sounding than a DD track.

I seem to recall this coming up before here, and I thought they said that DTS and DD were NOT lossy formats, could be wrong though.

Man, this jerk beside me on the plane keeps reading my posts...maybe typing this will give him a hint!!!

[sy_lu]

They are lossy foramts but just like the video part of the DVD, the media creator can decide how much lossy compression to use. DTS in general has lower lossy compression than DD and therfore sound better. DTS claim they have better algorithm but they in general also end up with bigger files. In the early days before the dual layer's cost went down, many DVD were done with heavy compression to keep them in one layer. That was also why in the early days movies with DTS cost mmore because DD is part of DVD standard and DTS is not. To put DTS on DVD means additional space is required that often means dual layers. Even today, most of the movies makers rather put those useless "extra" in the disc than putting DTS sound track.

As a side note, DVD-Audio with DTS coding is a lossless format.

[N. Abstentia]

I guess there is kind of a grey area there somehwere, when I think lossy format I also think MP3 and WMA mainly because you're taking something huge (a CD) and compressing it down to something minimal (MP3, WMA) so of course there is going to be something lost.

But with DTS/DD, I'm assuming that they are encoded that way from the beginning so they are not really lossy because you're not taking it from something huge and making it much smaller. I'm just not that familiar with the encoding process I guess.

As far as the plane guy goes, start typing up a paper titled 'How To Make an Airplane Bomb' and maybe he'll leave you alone. Well on second thought...that might not be a good idea. In fact just reading the phrase 'Airplane Bomb' on an airplane is probably not good either. Oh well, too late now!

[Sir Terrence the Terrible]

As a side note, DVD-Audio with DTS coding is a lossless format.

This is not correct. Dts in general is a lossy format. However, in the absence of signal complexity, Dts goes into a lossless routine. For instance, a instrumental solo with no other instruments playing. Dts would operated in a lossless fashion. However, once other instruments enter into the mix, it goes back into lossy mode. On the other hand, DD has no lossless routine. It's goal is to always discard information regardless if there is a solo instrument or not.

Dts does have a lossless codec, but the data rates of the DVD platform will not allow it to ever be operated in that fashion on DVD.

[quote}But with DTS/DD, I'm assuming that they are encoded that way from the beginning so they are not really lossy because you're not taking it from something huge and making it much smaller. I'm just not that familiar with the encoding process I guess.[/quote]

No. All soundtracks destined for Dts or DD encoding begin as uncompressed PCM audio. During the encoding process they discard information that would be masked(or unheard by the ears) by louder sounds. The remaining signal(in the case of Dts) are encoded at 20bit resolution. With DD it is more in the neighborhood of 18bits. The goal of Dts's encoder is to code as much of the PCM signal as it can without discarding data. Dolby digital's goal is to discard as much information as possible without noticeable sonic degradation. IMO, they are a failure in this goal.

[sy_lu]

This is not correct. Dts in general is a lossy format.

I stand corrected. One would think since DTS does have a lossless codec; the larger storage space and MLP for the DVD-Audio, the 96/24 DTS would be lossless for DVD-A. But, apprently that is not the case. Too bad. But that brings on an interesting question. Is lossless MLP coded 48/24 DVD-A sound better or the lossy 96/24 DTS coded DVD-A?

[Sir Terrence the Terrible]

I stand corrected. One would think since DTS does have a lossless codec; the larger storage space and MLP for the DVD-Audio, the 96/24 DTS would be lossless for DVD-A. But, apprently that is not the case. Too bad. But that brings on an interesting question. Is lossless MLP coded 48/24 DVD-A sound better or the lossy 96/24 DTS coded DVD-A?

Man!!, this is a tough question. 96/24 works in the lossless mode quite a bit depending on the complexity of the signal. I am going to have to do a DBT on this one and see what I hear. Thanks for peaking my curiosity!

[eisforelectronic]

DD=10:1 compression DTS=5:1 compression

[Sir Terrence the Terrible]

DD=10:1 compression DTS=5:1 compression

Actually its DD 10:1 compression at 448kbps, and 14:1 at 384kbps. Dts is 5:1 at 754kbps, and 3:1 at 1509kbps. At any rate, when dealing with lossy coders, the amount of compression applied does not always mean lesser or better quality. IMO, the amount of bits used to encode each channel is probably more important.

In the case of DD, the combination of not enough bits, and a high compression level DOES effect sound quality.