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C-Media CMI8788

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November 10, 2005 1:34:57 AM

This C-Media CMI8788 chip is going to do :

Dolby Digital Live
Dolby Pro Logic IIx
Dobly Digital Virtual Speakers
DTS CONNECT
DTS INTERACTIVE
DTS NEO:p C


and more....

http://www.cmedia.com.tw/product/CMI8788.htm

Anyone know when this puppy is going to in card form?? I want one!

More about : media cmi8788

November 16, 2005 1:23:35 PM

what's the benefit of Dolby Live encoding?

Dolby Live is a compressed format. So you are taking original audio generated in 24bit depth at 48 or 96 kHz resolution and squeeze it to push the contents down the light pipe to the external receiver. Does not make sense to me. Interferences are marginal, if we have 2 meter distance between PC and speakers. IF this distance was mutiplied by 10 this could deem useful ... but who is gaming with his speakers 10 meters away from PC?
The only thing I can think of when this Dolby Live thing could be useful is when you wanted to live broadcast in 5.1. - provided you had enough bandwidth.

So what is the benefit really?
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Anonymous
November 17, 2005 7:21:32 PM

The benefit is as you have pointed out interference, or the lack of it. Home theatre systems where PC's double as a high end game console seem like a likely scenario where one might not necessarily appreciate being limited by short cables. BTW If I were at your location I could definitely make enough noise with some of my radio equipment such that even your 2 meter cable would seem to long for you. It's all relative you know.
November 21, 2005 10:37:09 PM

You are right saying it is relative. I can see circumstances under which quality loss thru compression would be lesser than quality loss thru interferences. But in MOST scenarios this would not be the case as properly shielded cables do not interfere with other properly shielded cables.
January 17, 2006 11:28:23 PM

You guys really do not understand the way Dolby Digital Live works or even is beneficial.

Using DDL has absolutely nothing to do with interference or distancing from the source. It has to do with the ability to reformat multiple discrete channels of audio, into a single multi-channel stream that can easily be decoded by just about any multi-channel home receiver. How many recievers have discrete analog inputs for 5.1 audio? Well, not nearly as many as have digital inputs and dolby digital decoding.

It is very practical and is necessary for convergence on the PC into the living room.

Additionally, games that use DirectSound3D will be able to output in a DD format thanks to the soundcard being able to convert the source material to DD.

So as to DDL being useful, I hope that this answers your questions.
January 18, 2006 6:41:06 AM

Great answer, I've been promoting DDL for HTPC for that very reason. And that's about the only place I've really pushed DDL. It seems that people think building an HTPC means using some kind of Creative sound card, only to find they can't input all the channels on the typical home reciever.
January 18, 2006 7:19:05 AM

Some people are willing to pay for DDL (and the possible SQ losses in gaming) in order to preserve music sound quality by going digital to the receiver, instead of going all analog (because they are using unpowered speakers). At least, that's how I would justify it; not sure how others would.
January 18, 2006 10:00:11 AM

i might very well be wrong... but when the sound card encodes the audio data in Dolby Digital 5.1 compression, and streams it to your receiver... isnt the audio stream decoded using the receivers DACs, instead of your sound cards DACs? (bypassing your sound card, aside from the encoding)... potentially resulting in improved sound quality then, even before it was compressed? because more than likely, your receivers DACs are much better than your sound cards DACs... again, im not entirely sure, but that might be the case

...but then when i think again, i guess even 6 analogue cables streaming uncompressed data from your computer to your receiver, would provide 'possibly' better sound quality, if youre still only using your receivers DACs... but not when using your sound cards DACs... but yeah, one cable is definetly less of a hassle than 6+ lol... not to mention, usually you can use your receivers effects and enhancers with AC3 and DTS compressions, but usually not with the multiple analogue connections, (maybe some receivers allow you to though)
January 18, 2006 11:25:50 AM

Quote:
You guys really do not understand the way Dolby Digital Live works or even is beneficial.


Let me disagree with you and explain why

Quote:
Using DDL has absolutely nothing to do with interference or distancing from the source.


It does. Why are you using digital connection in the first place? To avoid noise caused by the interference with other cables/devices. And to avoid potential grounding problems ( i.e.. groundloops).

My point was: most home PC users do not have these problems and do not hear the difference between analog and digital connection. If they hear difference it's down to quality of the DAC.

Quote:
It is very practical and is necessary for convergence on the PC into the living room


I guess a group that will benefit are manufacturers and retailers - not consumers. As I argued before benefits of DDL are doubtful. DDL is a LOSSY format and introduces some audible latency. That was my problem with Soundstorm and the reason I, in the end, went for soundblaster card.

I do agree then one cable is more practical then 3 cables.
But let's not get mixed this comfort of use with sound quality.
Also, DDL is arguably, beneficial only in regard to sound in games that cannot be sent digitally to the receiver without encoding into some kind of digital multichannel stream. DDL brings no benefit to music or movies with real DD or DTS soundtrack.

I stand by what I have said: DDL is not a panaceum for all troubles, it's just a cheap work-around at the cost of sound quality. I prefer to have a decent soundcard with high SNR DAC and (for games) to go analog to the speakers
than
to have delayed sounds as a result of DDL...


Having said that I am waiting for DTS Connect, this seems to have far better bandwith that DDL, so maybe it will be free from these typical DDL problems.
Anonymous
January 18, 2006 7:14:40 PM

You are right I know nearly nothing of the dolby digital live standard. The description you have given for DDL is it performs the same function that SPDIF has been handling for many years....a serial data bus. Why do we need some new standard for the same old thing we have been doing already? BTW SPDIF is another standard that I only know enough about to be dangerous, so go easy on me here.

If it is not the benefits of digital signalling we are after here what exactly does dolby digital live bring to the table that we didn't already have?
January 19, 2006 6:15:46 PM

uncle_ben, do you honestly believe that the DA converters on a run-of-the-mill soundcard (yes, a soundblaster qualifies as such) are going to be superior or even equal to that of a reasonable DD/DTS capable receiver? Computers are very electrically noisy devices. Are you going to be able to run quality shielded cables from your soundcard to your receiver? Realistically good cables aren't cheap. Coax or a fiber optic cables are substaintially cheaper, because you only need one cable versus three or even six depending on your configuration.

You mention DDL being lossy. Of course it is. Is it noticeable? Not to 99.9% of the population. The dynamics of most multi-channel material, will mask any loss in DNR. Are you going to notice a slight loss in DNR when you're running around playing HALO or Half-Life or some other game? I seriously doubt it. What about when you are playing your multi-channel MP4 encoded movies? Again I doubt it.

The one thing you mention, that real troubles me is when you say that DDL brings nothing to music of movies. Hmm... I will agree and disagree with you, and this is why. I think you keep confusing DDL with a silver bullet for all program material. DDL serves ZERO purpose when the source material is already DD encoded. In such cases, DDL should not be used. It makes about as much sense as zipping a zip file. The file doesn't get any smaller, just more obfiscated. The purpose of DDL is to encode non-encoded multi-channel source material into the DD format. That is all, nothing more.

Also, be very careful about trusting soundcard specs. At best, they are a best case scenario. At their worst, they may not be representative of how you intend to use the product. Soundcard specs are not as detailed as consumer audio equipment and they are often misleading. Laws are in place for detailing audio equipment performance, and soundcards do not to my knowledge have to follow those laws at this time.

And lastly, I am looking forward to DTS Connect myself. Maybe it'll be better. Who knows, but we will find out soon enough. The only issue is that not everyone that has a DD decoder has a DTS decoder.
January 19, 2006 9:30:04 PM

uncle_ben

I think people get DDL cards so they can 1) get surround gaming effects and 2) music that's not resampled ala Creative cards via analog

This is the usual reason I hear from most users, its for music (obviously they turn DDL off during music playback).

As for comparing DACs, well if someone is using "higher end" speakers like unpowered bookshelves, then the receiver is usually an economical decision for the amp. Given these circumstances, since you will be running into the receiver's DAC anyway, you might as well pass-through digital rather than having the redundant effects of DAC-ADC-DAC.

Finally, DDL is lossy. Yep. And the source (audio stream for games) is something pretty bad anyway, well below bandwidth of a 128kbps mp3. Now the argument to buying computer speakers for gaming alone makes sense if you don't have any since the source is so weak, but if you already have a good speaker setup, its redundant, so DDL is a method of enjoying gaming with a setup you already have.
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