Is Your S/PDIF Bit Perfect? Here's a Test!
Dec 27, 2009 at 12:25 PM Thread Starter Post #1 of 33

UncleFestive

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Hello all, I am a chronic lurker around here, usually don't have much to add, but I had to pass this on, maybe some of you who I have learned from over the years will find value in it!

I have a Gateway Laptop with an Audigy 2 ZS PCMCIA sound card. I've always used the analog out to my Heed Canamp for music listening. I recently started using the optical out to an old JVC receiver, with MediaMonkey using Kernel Streaming Output V 3.63, and listening to my HD650's thru the receiver's headphone jack in preparation for adding my Audio GD Compass when it arrives.

I really want Bit Perfect playback but I've always read that no matter what, a Creative sound card up-samples to 48khz. I'm going to debunk that myth, and declare my Audigy is passing Bit Perfect to my receiver. You can too by reading and following the steps on this page:

FAQ: Kernel Streaming and the REVO - AVS Forum Archive

The concept is pretty simple: If you play a DTS encoded signal and it is resampled through your soundcard or your computer (kmixer or other), you'll get nothing but white noise. If it passes through bit perfect it will play as intended. Be aware the digital signal must be input into a receiver capable of decoding DTS. Most home theater receivers are capable of this. A more in-depth explanation of ASIO and Kernel Streaming, along with links to download DTS encoded media are provided on this page.

I downloaded one of the songs and ran the test. Digital out to the receiver yielded perfect reproduction of the source! Bye Bye Creative resampling myth! Bit Perfect Rules!
beyersmile.png


Now if I only had my Compass....
tongue_smile.gif
 
Dec 27, 2009 at 4:57 PM Post #2 of 33
I am using an Onkyo HTX-22HD with my computer and used AC3Filter in order to get DTS straight through to the Onkyo for it to decode the 5.1 sound, no problems with it.
 
Dec 29, 2009 at 5:15 AM Post #3 of 33
thanks OP....trying to figure out if/what I need to better my CD players sound quality (Arcam CD73), by streaming files from computer to PS3 -->Dac--->integrated using PS3 Media Server.

I can confirm that I am getting no upsampling of the digital source in the PS3 and it is delivering bit-perfect into the reciever.

Now I just need to add a dac to the mix so I can compare to my CDP.

The PS3 is a bit too noisy...wonder what I can do about that.

Thanks again.
 
Dec 29, 2009 at 5:36 AM Post #4 of 33
hooked up to either my old sony or either my old or new Onkyo HT receivers, i just press the 'display' button on the receiver remote, and it tells me what it's receiving.

'course, it usually displays it for a second or two when the stream first starts, too.

The article is misleading because the old dolby 5.1 signals use the same clock as 48khz stereo pcm, so an SPDIF pathway that only supports that clock will do either 48khz s16le or dolby digital, no problem.

The 1.5mbit DTS signals use the same clock as 96khz s16le, iirc.

If your receiver tells you that it's receiving 44.1khz pcm, it's probably receiving 44.1khz pcm.

(I lurve my TX-SR707)
 
Dec 31, 2009 at 8:04 PM Post #6 of 33
Quote:

Originally Posted by krmathis /img/forum/go_quote.gif
Perfect reproduction here, using the MacBook Pro and Isabellina.
Playing back the "The Other Side - DTS (WAV @ 44.1kHz/16-bit Stereo)" file from Free DTS and AC-3 (Dolby Digital) Downloads - Kelly Industries



I'm becoming convinced that computer-based music servers are much simpler to implement on a Mac. Must be why most pro recording studios use them
very_evil_smiley.gif


What I've always understood is that Redbook stereo CDs are 44.1kHz/16-bit/2-channel (stereo) audio files, and with the extra space available on DVDs they went to 48kHz/16-bit multichannel audio files for surround sound. That's why the adaptive USB audio standard supports both 44.1kHz/16-bit and 48kHz/16-bit files.

So I am probably over-simplifying but that's my 2¢
wink_face.gif
 
Dec 31, 2009 at 8:11 PM Post #7 of 33
My DacMagic upsamples so there's no way to get bit perfect output. But I don't really care, the sound is great
 
Dec 31, 2009 at 8:35 PM Post #8 of 33
My X-Fi Titanium is bitperfect via ASIO and automatically switches the samplerate to match the source. That is, of course, when the abysmally terrible drivers aren't trying to screw me over.
 
Dec 31, 2009 at 8:46 PM Post #9 of 33
Quote:

Originally Posted by .Sup /img/forum/go_quote.gif
My DacMagic upsamples so there's no way to get bit perfect output. But I don't really care, the sound is great


But, the point of the test is to find out if your source is outputting bit-perfect audio. Even if your DAC will do its own upsampling, you could use the test to make sure that it's being fed a bit-perfect signal. Otherwise you'd be resampling twice.
 
Dec 31, 2009 at 10:20 PM Post #10 of 33
I just wanted to add, that forum color layout is effing terrible! And I will be back with my tests for bit perfect when I get home from work
smily_headphones1.gif
 
Jan 1, 2010 at 12:05 AM Post #11 of 33
Quote:

Originally Posted by UncleFestive /img/forum/go_quote.gif
Hello all, I am a chronic lurker around here, usually don't have much to add, but I had to pass this on, maybe some of you who I have learned from over the years will find value in it!

I have a Gateway Laptop with an Audigy 2 ZS PCMCIA sound card. I've always used the analog out to my Heed Canamp for music listening. I recently started using the optical out to an old JVC receiver, with MediaMonkey using Kernel Streaming Output V 3.63, and listening to my HD650's thru the receiver's headphone jack in preparation for adding my Audio GD Compass when it arrives.

I really want Bit Perfect playback but I've always read that no matter what, a Creative sound card up-samples to 48khz. I'm going to debunk that myth, and declare my Audigy is passing Bit Perfect to my receiver. You can too by reading and following the steps on this page:

FAQ: Kernel Streaming and the REVO - AVS Forum Archive

The concept is pretty simple: If you play a DTS encoded signal and it is resampled through your soundcard or your computer (kmixer or other), you'll get nothing but white noise. If it passes through bit perfect it will play as intended. Be aware the digital signal must be input into a receiver capable of decoding DTS. Most home theater receivers are capable of this. A more in-depth explanation of ASIO and Kernel Streaming, along with links to download DTS encoded media are provided on this page.

I downloaded one of the songs and ran the test. Digital out to the receiver yielded perfect reproduction of the source! Bye Bye Creative resampling myth! Bit Perfect Rules!
beyersmile.png


Now if I only had my Compass....
tongue_smile.gif



Try to use files of different sample rate, not only the 48Khz which is the goal of the Audigy,

PLEASE if someone could test Wasapi for bit perfect output, so I can finally change to 7,
THANKS

BTW, happy new 2010, finally 2012 is coming..
 
Jan 1, 2010 at 1:54 AM Post #12 of 33
Yes, that's a good point. Make sure you try the 44.1khz WAV files. If a card resamples to 48khz, it will probably pass 48khz DTS with no problem.

I get bit-perfect output with WASAPI and Windows 7. That's with a Xonar D2, using the Foobar plugin, with the device set to "S/PDIF Pass-through." It doesn't work if the device is "speakers" (the default), so I think the card is doing some kind of conversion to everything using that device.
 
Jan 1, 2010 at 10:28 AM Post #13 of 33
Quote:

Originally Posted by SirDrexl /img/forum/go_quote.gif
Yes, that's a good point. Make sure you try the 44.1khz WAV files. If a card resamples to 48khz, it will probably pass 48khz DTS with no problem.

I get bit-perfect output with WASAPI and Windows 7. That's with a Xonar D2, using the Foobar plugin, with the device set to "S/PDIF Pass-through." It doesn't work if the device is "speakers" (the default), so I think the card is doing some kind of conversion to everything using that device.



Yes, I've noticed that with vista, only selecting spidf as default device got the automatic convertion rate in Creative audio creation mode,
at least wasapi is bit perfect after all..
 
Jan 1, 2010 at 11:58 AM Post #14 of 33
Not to hijack or be disrespectful, but what's the deal with bit perfect? Does upsampling increase latency that much? If you are just listening and not trying to capture live sound, does it really make a difference?

I'm asking because I cannot find the term "bit perfect" in FallenAngel's "Before asking about digital audio: READ this Digital Audio Primer"
 
Jan 1, 2010 at 3:59 PM Post #15 of 33
Quote:

Originally Posted by grokit /img/forum/go_quote.gif
Not to hijack or be disrespectful, but what's the deal with bit perfect? Does upsampling increase latency that much? If you are just listening and not trying to capture live sound, does it really make a difference?

I'm asking because I cannot find the term "bit perfect" in FallenAngel's "Before asking about digital audio: READ this Digital Audio Primer"



Well, this is Head-Fi!
wink.gif

Where the sake of mind is important. Knowing that the audio stream is bit-perfect without loss.

Some are pleased with lossy encoded audio files and probably do not care about bit-perfect playback. While others use lossless encoded files and go for bit-perfect playback to match it.
Each to their own I guess!
 

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