[libdts-devel] Re: DTS decoder

[Gildas Bazin]

On Wednesday 18 February 2004 05:42, Benjamin Larsson wrote:
> I've been playing around with the DTS decoder and to my ears it sounds 
> good. I can clearly hear hard to code sounds like rain and sea waves. 
>

Good :)

The development version also includes support for high frequencies vector 
quantization (usually not used in DTS audio CD's but seems to be used in 
DVD's which are using lower bitrates) so it should sound even better now 
( although I personnaly can't hear a difference... but my hardware is 
crappy anyway ;).

That means that as long as you don't use any downmixing, the sound quality 
should now be as good as it can be.

> Only one time of 30-40 a pop/click appeared in the music, could be a 
> mastering issue as well.

This could also very well be a problem with the downmixing routines (they 
need some more work) as they can easily overflow (right now all channels 
are assigned a 1 coefficient). I found the official downmixing coefficients 
table so I'll implement that when I've got time.

> Though I've just used a set of headphones the 
> extra dimension of space seams to be there. And the support for 
> different streamtypes seams to cover the usual ones because every file I 
> have can be played, even a 6.1 DTS sample found here:
> 
> http://www.sr.se/laddahem/multikanal/dts/norgeES.zip
> 

Yep, that's an interesting feature of DTS. The extensions can just be 
ignored by the decoders if they want to (and which we do right now).

By the way, if anybody has a DTS sample using the 96/192kHz extension, I'd 
be glad to have a look at it. Not that I'm planning to add support for it 
just now (mainly because the spec doesn't cover the extensions) but I'd 
like to have one to add to my test samples collection ;).

> The only issue I could find was when vlc-0.7.1-test1 stopped the 
> downmixing to stereo and only gave me the backchannels. Maybe I just 
> messed up my configuration but I couldn't easily find an option to fix 
> it. But before I messed it up the Basic DVD played just fine with DTS 
audio.
> 

Strange. I'd advise you to go into the preferences and "Reset All", just in 
case you changed something by mistake.

Thanks for the report :)

--
Gildas

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