"Hello" and some questions (24-bit source)

[HexiBase]

Hi everyone. My name is Pete and I'm new here (this being my first post and all...) I'm the owner of HexiBase.com which, if you visit, you'll notice that I have a firmly established car audio background. At any rate, the reason I'm here is because of my fascination with high quality sound. I suppose I am an audiophile in the making. I've made some strides in expanding on my understanding of infinite environment acoustics and, with that, I have a lot of questions which I'm sure I've come to the right place to have answered.

Anyway, here's my scenario: On account of convenience, I use a PC as my audio / video source. I'm already aware that because of the CD/DVD-ROM timing issues, it is next to impossible to achieve perfect bit-for-bit music reproduction, even from a standard RedBook format CDs (you can certainly tell an obvious difference between a high quality CD transport / pre-amp setup and a regular CD-ROM). I did, however, find a way to retain a lot of the detail that's lost somewhere between the CD-ROM and the line-level out jacks - I rip my CDs onto the hard drive into a lossless format (FLAC is my personal format of choice). There does seem to be a lot of audible difference between a track on a CD and a FLAC file. I particularly enjoy the sound of the 24-bit / 96Khz FLAC files that I've gotten a hold of that were ripped from studio master quality audio DVDs.

So... With that as my sound source, I've come across an interesting article (the link to which I can't list until five posts from now), needless to say, it's a review, of sorts, focusing on a number of sound cards. The interesting thing that I've learned from it is that just because a sound card has a 24-bit DAC, doesn't at all mean that you can expect it to be capable of 24-bit output sound resolution. Most sound cards aren't true 24-bit capable sound cards even though they have a 24-bit DAC; the problem is that, in most cases the 24-bit DAC is fed by a 16-bit sound chip. That's kind of like expecting a stereo sound by feeding a mono signal into a stereo amplifier. Garbage in - garbage out.

With that, I can get to my first question: What sound cards are there available that offer true 24-bit output sound resolution? I've read up on quite a few and the companies never specify whether a sound card has a 24-bit DAC with a 24-bit sound chip (true 24-bit) or a 24-bit DAC with a 16-bit sound chip... I presume that I'm not the only one here trying to get some decent sound out of a computer-driven home theater and I hoping my dilemma has been long since resolved by someone here. I look forward to reading about it in your responses.

 

[Davemcc]

Pete,
I just wanted to say Hi and welcome to the forum. Your first post is way over my head because I know nothing of computer sound cards. I'm sure there are others here that can help you. So, "Hi and welcome to the forum".

 

[agarwalro]

CDs are 16bit depth media. So there is no point trying to encode it at 24bit depth using a 24bit processor. You cannot create data where none exists.

You will get 24bit depth processing only in ultra expensive studio grade equipment. At least for now...

Here is an article that gives an explanation for the bit depth and its effect on sound quality. 16 vs 24 Bit Audio. The article os geared towards recording but makes for a very good read, and the principles apply here.

 

[corebreach]

There does seem to be a lot of audible difference between a track on a CD and a FLAC file.

I hope you're kidding. In comparisons between WAV files ripped directly from the CD (that is, no transcoding, just the audio from the cd) and FLAC cd rips converted to WAV, with the exception of some header info, the resulting WAV files were bit-for-bit identical. Unless there's a material error in the way you're ripping CDs or the way your FLAC decoder plays files, the two sources should sound identical (assuming the same DAC and other external parameters).

EDIT: Sorry I'm still looking for the citation where I read this, if I find it I'll post it.

 

[OttoMatic]

I'd have to agree with corebreach in that there should be no difference between the CD and the FLAC copy. I also use FLAC for all my audio files. I've listened to the original CD vs. the FLAC streaming from my PC, and can tell no difference. Perhaps you are using an analog out from your PC, or perhaps there is some type of processing going on in the PC that's not occurring in the original...

As to sound cards, it sounds like you are going using an analog output from your PC (again, that might explain a difference between FLAC and CD -- you're using two different DACs for playback comparison). Many of us use digital out from PC to preamp, and allow the DAC stage to occur there. There are many fine preamps on the market that will do a better job of digital to analog conversion than most PC sound cards. That said, there are nice sound cards out there, but I've never been too interested in researching them -- not only because I believe that my preamp has a better DAC than almost any sound card, but also because surround decoding can be handled so much better by a dedicated preamp (i.e., watching movies). Actually, I've never played much with movie decoding software for sound cards, but if the sound card software that I've used (from a variety of manufacturers) is any indication, there will remain much to be desired. Anyway, going digital out to a preamp is the only way to go, IMHO.

As noted above, redbook CD is only a 16-bit data word. You can upsample it, and you can upscale it, but it's still only 16 bits to start. It may be possible to get a little more resolution out of it by these methods. Again, these can be achieved in many home theater receivers and processors. My old Outlaw would do a 24/96 mode, I believe. It sounded pretty good, for the most part. My Cary doesn't upsample, but it sounds great nonetheless.

There are many options out there. Good luck!

 

[MDS]

If there is a difference between a FLAC and a WAV then the FLAC encoder is broken; ie not lossless.

No citation is needed. Decode the FLAC and load it and the WAV into an audio editor. Invert one of them and paste-mix it into the other. If the result is all zeros (which it will be) the two files are identical.

 

[HexiBase]

I appreciate all the responses. I guess it would help for me to further elaborate on the rest of my set-up. It's essentially an AMD Athlon 64-based gaming PC with a SoundBlaster Audigy PCI sound card. The sound card sends line-level signal to three separate T-Amps: One for front left & front right, one for rear left & rear right, and one for center & LFE channel. And, of course, The T-Amps connect directly to my speakers (I build a lot of different HT speakers so the amps feed whatever I happen to be auditioning at the time). So... That's my rig.

Now, I do understand there not being any need for 24-bit resolution when playing RedBook CDs as they're encoded at 16-bit depth (kind of like you don't need a color TV for a B&W movie). My concern with 24-bit resolution output capability comes into play when I want to listen to my 24-bit FLAC files that I've extracted from a number of DVD-A albums. I'd like to be able to enjoy them without resorting to the system having to down-mix them to 16-bit resolution (which essentially defeats the purpose of them being 24-bit in the first place).

As for the difference between the sound of a FLAC and a WAV file of equal sampling rate and resolution - there is none - they sound identical. I do, however, notice a difference between playing a track directly from a CD versus playing the same track ripped onto the hard drive in a lossless format. I made certain that I'm not using any sort of equalization for the CD-ROM or the wave output and I'm not using any sound altering or "enhancing" filters when I capture audio from a CD into WAV PCM or FLAC. Quite frankly, I'm stumped as to what's causing the difference in sound, I'm simply acknowledging that the sound seems "fuller" when played off the hard drive.

 

[MDS]

The original Audigy was one that touted 24 bit playback but in reality was only 16 bit and maybe that is the the type of card the article you originally mentioned was referring to.

The Audigy 2 is 24 bit (input) but still followed the AC'92 guidelines and resampled everything to 48 kHz because its internal audio processing chip could only work at 16/48.

I think the Audigy 2 ZS that I have does truly support 24 bit input at 48 and 96 kHz sample rates without resampling but I have no way to prove it as I have no 24 bit sources.

As for the difference between playing a CD and a FLAC/WAV from the hard drive, there could be a subtle difference in the sound quality you hear but as you've noted the files themselves are identical. The playback chain comes into play and would probably account for any perceived difference.

Playing the CD and using digital output means the player will send the data directly over the PCI bus. Other devices are using the same bus so there could be subtle timing differences that could account for the difference but it should be really minute unless there is a huge load on the CPU from other programs at the same time.

 

[HexiBase]

Yes, the article that I've mention does talk about SB Audigy as one of the cards. As I've said before, I can't list links on here until I've had at least five posts on this forum (and this is my third) so I'll just space it out:

h t t p : / / t e c h r e p o r t . c o m / a r t i c l e s . x / 4 5 7 7 / 1

There... If you take all the spaces out of the above address, you can see the article that I'm talking about. I was actually very disappointed with SoundBlaster and other companies, in general, for misleading people like this.

As for the difference in sound between direct CD-ROM playback and a lossless file... The only way that I've been able to explain it for myself is through another article that I've read that expanded on the difference between a high-quality CD transport and a CD-ROM. You'd think that a computer's CD-ROM would provide bit-for-bit perfect signal reproduction. Well, evidently, that's not the case because of "timing issues" between the CD-ROM device and the motherboard (whatever that means). I can only assume that by reading this data from a device that's less susceptible to lag or a device that doesn't have it's own clock speed (or processing frequency) such as a hard drive, some of these "timing issues" are addressed. I don't know - I'm just speculating.

The easiest way I can think of for you to get a hold of a 24-bit test sample would be to extract one from a movie DVD. I use a program called "DVD Audio Extractor". It's pretty handy; you can select any given sound track from any given chapter and capture it to a lossless format like WAV or FLAC. If the sound track on the particular DVD is 24-bit, you can extract it at that resolution. (Same with DVD-A albums). If you play your WAVs or FLACs with a simple player like Media Player Classic (my personal favorite) you will be able to tell immediately if your sound card doesn't support 24-bit resolution because the sound track is going to sound like hiss. (Make sure your player doesn't automatically sample audio down).

 

[dem beats]

Pete,
You're reputation precedes you sir.

A huge welcome to you onto this site. I had even applied to get onto your site, but both times I never got an email back. You're work is quite amazing and I wanted to work with you on a project I was going to get into for a DIY set up on my HT.... anyway.. I now sound like a fan boy, but in truth you've done some amazing stuff. Thundra at ROE recomended me to you some time back... on to your issue.

I am a Mac user, and it's been years since I messed with ripping audio and such, and maybe someone else would knwo why, but I was able to rip audio using an older form of audio converter off DVD's after creating an image(copy) on my HD. I did this often as DVD's on the old mac g3 I had would have the audio not sync up with the video and by the end of the movie the audio track would be almost a second or more late/early, but when i created a disk image and played it from the HD itself it never had an issue. CD's and MP3 format were almost always identical, but that was when I ripped it myself. Many other folks had huge losses in audio when they ripped the audio to MP3

 

[mr-ben]

Hi Pete - I have a few suggestions for you.

For the sound difference between a CD and Flac - do you happen to have the little wire that connects your CD drive directly to your sound card? This is a little 4-connector cable that's thin and usually grey. If you do, try unplugging it and see if you still get music from the CD. I'm guessing that when playing a CD you're hearing the sound converted to analog by the CD-Rom drive and your soundcard is just a passthru, while when playing Flac files you're hearing the conversion from the (better) sound card DACs and analog output. If that's not it, then I have no clue what the difference could be that you're hearing.

You commented that you use "DVD Audio Extractor" to get the sound from DVD-Audio discs. If you take a look at the FAQ for that program (http://www.castudio.org/dvdaudioextractor/faq.php), item #7, you'll see that you're not actually extracting the high-resolution audio from the discs. Instead, you're getting the DTS or AC-3 tracks, which are a compressed format. In other words, you're not even starting with 16bit audio, let alone 24bit. I don't have any connection to and have never used this service, but I know that Linn Records offers many high-quality Flac files for download: http://www.linnrecords.com/linn-help-downloads-studio-master-quality-album-downloads.aspx

I think I remember that the Audigy line of cards supports decoding of true DVD-Audio, so if you play any DVD-Audio disc using their special player, you should be able to hear an improvement there compared to your extracted Flac files.

As for your original question of true 24-bit sound cards, I've been looking closely at some cards from E-MU, which I believe are probably going to be the best sounding cards you'll find for a PC, at least on paper. http://www.emu.com/products/

 

[HexiBase]

I had even applied to get onto your site, but both times I never got an email back.

Hey, I appreciate the welcome. As for my site, you should be able to successfully register on my forum now. There was quite a period of time when I manually accepted / deleted login requests because of all the spam bots registering and I guess I was a bit overprotective with the delete button. I've got better security and automatic verification set up now so go ahead and climb aboard.

do you happen to have the little wire that connects your CD drive directly to your sound card? This is a little 4-connector cable that's thin and usually grey.

I sure don't. The only things coming out of my ROM are the power / IDE cables.

you're not actually extracting the high-resolution audio from the discs. Instead, you're getting the DTS or AC-3 tracks, which are a compressed format. In other words, you're not even starting with 16bit audio, let alone 24bit.

A very good (and pertinent) observation. Damn... I guess, until I can find proper DVD-A decrypter software, I'll have to stick to my downloaded 24-bit FLAC files (that and actual 24-bit DVD-As). This kind of gets me to wonder how others manage to extract 24-bit sound from DVDs...

 

[fmw]

A very good (and pertinent) observation. Damn... I guess, until I can find proper DVD-A decrypter software, I'll have to stick to my downloaded 24-bit FLAC files (that and actual 24-bit DVD-As). This kind of gets me to wonder how others manage to extract 24-bit sound from DVDs...

They don't. They listen to 16 bit audio.

 

[mr-ben]

This kind of gets me to wonder how others manage to extract 24-bit sound from DVDs...

It depends on the disc. For example, I have the Blue Man Group's "The Complex", which contains a 2-channel 24bit/96k PCM track in the DVD-Video portion of the disc, which you should be able to rip. I think most of the DVD-Audio discs I have don't contain anything but AC-3 or DTS in the video portion though. I don't own any of the non-DVD-Audio music-video/concert type DVDs, but I'd guess some of them contain high-resolution 2-channel PCM on them too, although most people probably would prefer surround sound in AC-3 to high-quality 2-channel sound.