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[bobe4]

I have M-Audio's 2496 soundcard with spdif coaxial out running to my harman kardon receiver which has a processor that decode my mp3's right in receiver itself.  BUT the HK receiver indicates it's not getting receiving mp3s - thus it's being decoded in the computer instead of passing just the straight data to the receiver.

So, how do I need to set this up where the mp3s wont be decoded in the computer?  

Do I need to set the Playback/Output settings to a certian setting (direct sound, wave out, - what is ASIO by the way?).  I've messed some with this but without success.

please help!

[shAf]

Confirm the following is what you want (... as opposed to what is usually done ... see below).

Do you really want the compressed MP3 data to be streamed out the S/PDIF connector to your HK digital input for the HK to decompress and convert to analog (DAC)...

...OR...

do you want MC to decompress the MP3 data and stream it out the S/PDIF connector for your HK DAC.

I believe you want the latter, in which case the M-audio card's output ... analog and S/PDIF ... should be alive with the stream.  Confirm what you're trying to do, and get back ...

hth ...

[bobe4]

Thanks for the reply.

I want the former - for the HK to decompress/decode it.

[Matt]

There's no way to stream compressed MP3 data out of Media Center's playback engine.

However, MC's mp3 decoding engine is probably better than a hardware implementation, so I'm not sure it'd be that great.

[phelt]

bobe4 - No knock against HK, but I doubt that their MP3 decoder is better than the one implemented by MC. Also, should there be improvements to the decode process for either, the upgrade process is likely to be dramatically easier with MC.

If your motivation is to keep as clean a signal as possible for as long as possible in the audio chain, bypassing MC's decode would not aid significantly in that effort, but using the SPDIF output does, IMO. My own setup is SPDIF optical out to a DAC/amp combo, bypassing some of the potential noise problems of running analog outs from a soundcard.

If your motivation is just to play with an interesting feature on your new audio equipment, I guess you need to see what HK manuals/support has to say about it. Any chance you could post the model number so that I can have a look at it?

[bobe4]

My model is an HK AVR 220... and the newer avr 225 has the same feature.

My motivation for this was that reading I did some time ago said that it was better to convert outside the computer - although part of the reason i got this receiver is it was suppose to have a good processor.

Right now i'm running optical spdif out, what is the best setting to have for the output (Wave out, direct sound, or ASIO)?  

THEN in this same Playback/output dialog the "settings" button brings up another option (which changes based on the above setting - e.g. for wave out it gives soudn card or wave mapper).  what is the best setting here?

[phelt]

I can understand an argument for 'conversion' to take place outside the computer. To me that would mean 'digital to analog conversion'. And the processor that HK uses looks to be good, if their specs are to be trusted. Again, nothing against HK particularly, just that there's a lot of outright lying exaggeration in the industry about performance specs. I doubt that there's anything bad about their processor.

I usually try to set playback/output to the soundcard or device instead of wavemapper.

A primary ASIO goal is to provide lower latency, ie. quicker response time. Some folks have reported issues with ASIO playback, and M-Audio's Revolution appears to have an issue with using ASIO and the SPDIF output - perhaps there's another 2496 user who can share their experience. For XP my first fallback option from ASIO would be DirectSound. Your mileage may vary, and there are plenty of folks with strong opinions about these issues...

I'm sorry for being a hedger, but my recommendation is to try out a few variations in the settings and see what works for your configuration.

[Dietwhip]

The HK AVR-220 I believe has 192KHz/24-bit DACs.
That would make it better than most computer based DACS.

You can read about it here:
http://manuals.harman.com/HK/Product%20Information/AVR220PI.pdf
http://manuals.harman.com/HK/Technology%20Articles/HKH1112%20MP3%20Tech%20Sheet.pdf

Here are some quotes:
"†MP3 playback requires a compatible S/P-DIF
signal, or an optional transcoder such as the
Harman Kardon DAL 150.
...
For installations where a consumer wishes to play MP3 files directly from a computer-based source, the ... output of a compatible computer sound card is connected to one of the AVR’s optical or coaxial digital inputs. At present, the Turtle Beach Santa Cruz™ PCI card has the correct S/P-DIF output and, in the future, more computers and sound cards will include this capability."

The encoded original MP3 bitstream exists on your hard drive. That provides the infomation, according to the MP3 standard to decode two (stereo) audio channels.  The result of the properly implemented decoding algorithm are two bit streams. One for each of the two speakers.  If the decoding algorithm is implemented correctly, and runs in the proper environment, then the two output bitstreams can be verified to be bit perfect.  In fact there are test files that provide what the output should be to test whether the MP3 decoder is working properly.  They kind of give the answer ahead of time to the decoder writers.

I do not know if JRiver writes their own MP3 decoder or licenses someone else's code and glues/hooks it up to their Media Center proprietary product.
I would guess Matt know this answer, but may not be able to share that here.

Beyond MP3 endoded bitstreams, there are more advanced encodings of 6 and 7 channels. These include Dolby Digital 5.1, DTS, and variants of 7 channel encodings.  And there are lossless formats like APE, FLACC, lossless-WMA, etc.

In theory these more advance encoded formats could be stored and accessed through Media Centers Library, but I do not know if Media Center has a way to play these.  Matt would know if Media Center can play Dolby Digital 5.1.  I doubt Media Center can NATIVELY play lossless-Window Media Format!

Now the word 'play' is tricky. Play can mean 1- simply pass through the disk/DVD/CD resident encoded bitstream to other licensed software programs on your computer, or to pass it through to the sound card which has a capability to pass it through to your HK AVR's internal 192kHz/24-bit DACS.

I think the Media Center decoding either native or borrowed is 32-bits, but NOT 192kHz.

Originally there were no consumer available MP3 decoding cabable audio receivers/amplifiers/speakers and the PC was the only means to accomplish this.

Bottom line is (IMHO): it is better technically to pass the pure unencoded signal from the hard drive, or DVD, or CD to the 192/24-bit DACs and even full blown DSPs now in some HK, and Onkyo, and other high end audio gear.  More and more powered speakers have built in mulitprotocol decoding capabiltiy, if only you can get them the pure undecoded signal, hehe.   Windows is NOT a real time operating system. It has a hard time guranteeing it will/can keep up with tasks that must be done in real time. Especially when it is running multiple tasks.  Large buffers try to overcome Windows disadvantages.  But given sufficient loads, the PC will not be able to keep up. Software and hardware latencies will rear their ugly head.  Result: stuttering.  Anyone ever hear their system stutter once in awhile?

There is a largely political reason why digital pass through is not functional on many PC based sound systems.  But that is another story.

[LisaRCT]

WOW! Dietwhip, Great write. Thanks for the info.
I would love to see a thread on what can be done to best tailor a PC solely for audio use.

[phelt]

sigh.
I get slightly discouraged when I hear phrases like "bit perfect" or "192KHz decoding" applied to the decoding of lossy formats like MP3. It's an MP3. It's a lossy format. Dedicating a Cray to the decoding is not going to change that. 32 bits are arguably beneficial for carefully ripped and well encoded MP3's, but if you feel a compulsion for that level of quality, you should probably start with a more accurate foundation than MP3 compression.

As to stuttering, I haven't experienced this in about 5 years, through 2 or 3 systems, but I'm sure that it's possible if you're defragging while playing back music during a CD to CD burn on a Celeron  

Dietwhip: you might want to try Media Center. Given some of your statements, I think you might be pleasantly suprised by some of its features and capabilities. It also turns out to be quite good for actually listening to music as well  

[Monkeyboy]

sigh.
I get slightly discouraged when I hear phrases like "bit perfect" or "192KHz decoding" applied to the decoding of lossy formats like MP3. It's an MP3. It's a lossy format. Dedicating a Cray to the decoding is not going to change that. 32 bits are arguably beneficial for carefully ripped and well encoded MP3's, but if you feel a compulsion for that level of quality, you should probably start with a more accurate foundation than MP3 compression.

As to stuttering, I haven't experienced this in about 5 years, through 2 or 3 systems, but I'm sure that it's possible if you're defragging while playing back music during a CD to CD burn on a Celeron  

Dietwhip: you might want to try Media Center. Given some of your statements, I think you might be pleasantly suprised by some of its features and capabilities. It also turns out to be quite good for actually listening to music as well  

Thats funny, I started to write something very similar to this last night, but thought I might get abuse for it, totally agree. There are MP3s at the end of the day.
Rich

[Monkeyboy]

I certianly wasn't, and I don't think phelt was arguing against the fact that some devices are up to decoding MP3s. I think they are way past the task because MP3s are lossy and do not sound anywhere near as good as DTS or AC3. I myself have an external AC3 amp and use SPDIF (AC3 bitstream) passthrough for that where it has a 24-bit 96KHz decoder. But for playing my MP3s I simply pass it out the line out jack of my sound card, which is more than capable of reproducing the best sounds from the MP3s.
Please don't take this like I am saying do not do this, but I personally wouldn't spend too much time/money on it.
Rich

[Dave T]

Monkey:

So, you're doing the D/A in your PC?  Wouldn't you be better off sending it the digital PCM signal to your pre/pro to do the D/A?  For reasons already mentioned, the PC might not be the best place to produce analog signals.

But, I'm there on your comments about external processing of MP3's.  I understand Diet's comments, but I can't imagine that there would be any noticable improvement having the pre/pro process the mp3's, rather than just having the PC convert the MP3 to PCM and then the pre/pro doing the A/D.

- Dave

[Monkeyboy]

Dave,
I could, and have tried sending the MP3 as PCM via the SPDIF to my decoder, but this is my theatre system, which does not sound as good a my HiFi for music, although it is better quality (if you see what I mean). I cannot hear any better quality when the decoder plays the PCM to my HiFi having the line out. And seeing as this is supposed to be over 100dB S/N I shouldn't.
I don't have thousand pound theatre and HiFi system by the way so this could change when I do  
I am prototyping a device at the moment, which is digital, on a small board, with line out. It's main priority is reproducing an excellent quality audio signal, if care is taken this can be accomplished reasonably well.
Rich

[Dave T]

Ok, so you think the D/A in your sound card is better than that in your processor?  If you have a good sound card, and an inexpensive processor, then that could very well be the case.  But, if your processor is a good one, then it sounds like you'd agree that one is better off sending the processor a digital signal, rather than doing the A/D in the sound card.

[Monkeyboy]

No, I would not say the DAC in my sound card is better than my sound card, I think that the setup is geared towards Movies, which it is.
I think it is very easy to make the best of an MP3, thats all I was saying really  
Rich

[bobe4]

Dietwhip - thanks for the links and the insight.  Here are a couple of follow up questions from your post:

I assume that my 2496 m-audio spdif out card is compatible, am I right, or how do i find this out?

I assume that I would have to go outside of Media Center to play my music because of the post Matt gave above - if it is possible how do I set up MC to pass it through?