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More => Old Versions => Media Center 17 => Topic started by: batman87654 on November 14, 2012, 03:08:23 am

Title: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: batman87654 on November 14, 2012, 03:08:23 am

Hi,

can anyone please shed some light on why when playing a DVD the source sample rate is only 48kHz (should be higher) and why the source bit depth is 32bit (should be 24bit) ?? Completely confused.

When I play CDs it comes up as 16bit and 44.1kHZ, now that is to be expected so that is great. But can't understand the figures for DVD.

Thanks

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: Hendrik on November 14, 2012, 03:47:13 am

DVDs typically have 48kHz Audio. What did you think they have?
For bit depth, if its a lossy compression, it'll be decoded to 32-bit floating point. See this on the Wiki: http://wiki.jriver.com/index.php/Audio_Bitdepth#Bitdepth_of_Lossy_Formats

PS:
Lossy compressions include the common DolbyDigital/AC3 format used on DVDs, as well as DTS, and many others. The only lossless format on DVDs that i know of is PCM.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: InflatableMouse on November 14, 2012, 11:27:12 am

To complement, DVD-Audio can contain up to 192Khz/24-bits in stereo or up to 96Khz/24-bits for multichannel in L-PCM (either lossless compressed or uncompressed).

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: batman87654 on November 14, 2012, 02:06:29 pm

Thanks very much for the answers. Much clearer now. There's just one thing I still don't get. For a DVD Im playing that is 192Khz, still the source says 48kHZ. I have a capable sound card for this so not sure why? And how about for 96kHZ DTS, does MC17 not support this?

Thanks again

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: InflatableMouse on November 15, 2012, 01:33:27 am

Which DVD is it and how do you know its 192khz?

A DVD-Video can have 48 or 96Khz for PCM audio channels, anything else (AC3, DTS, etc) is (or I thought was) 48khz. I had not heard of 96khz DTS before but appearently that is supported on DVD in 2-channels only. I've never seen that being used though and I don't know whether its supported by MC.

Also consider what nevcairiel said about decoding lossy formats. Only (L-)PCM on DVD's is lossless as far as I am aware.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: Micromecca on November 15, 2012, 02:55:20 am

DTS 96/24 (http://en.wikipedia.org/wiki/DTS_(sound_system)#DTS_96.2F24) Supports upto 6 channels of 96/24 Audio on DVD format but requires a compatible decoder. I know that MC can bitstream it just fine but I can't remember whether it will decode it and pass it on as PCM, perhaps Nev could comment as my system is currently tucked away whilst decorating.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: InflatableMouse on November 15, 2012, 03:07:41 am

Thanks for correcting that. I was actually reading that wiki page on DTS 24/96, but missed the part where it says "prior to ...", interpreting it as only 2 channels were supported.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: Hendrik on November 15, 2012, 06:41:32 am

If it uses LAV Audio for DVD-Audio decoding, you will need the ArcSoft DTS decoder for 96/24, otherwise you'll just get 48kHz.
96/24 is one of the last DVD profiles thats not supported. That one, and the lossless extension in HD MA.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: batman87654 on November 16, 2012, 01:55:53 am

Thanks all.

Yes indeed it was a 96kHz DVD, got a bit over excited. Well done for still giving a good answer.

And thanks very much nevcairiel, I will have a look at ArcSoft DTS, or maybe MC 18 will support this.

Title: Re: DSP - Source sample rate and bit depth for DVDs not showing as expected
Post by: Hendrik on November 16, 2012, 02:27:03 am

Quote from: batman87654 on November 16, 2012, 01:55:53 am

And thanks very much nevcairiel, I will have a look at ArcSoft DTS, or maybe MC 18 will support this.

MC18 does not improve on this to my knowledge.

Here is info regarding the DTS decoder from ArcSoft:
http://wiki.jriver.com/index.php/Blu-ray#Decoding_for_DTS-HD

It talks about Blu-ray and DTS-HD, but the same concept applies to DTS 96/24.