please help me understand....SPDIF on motherboard. - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th July 2006, 02:24 PM   #1
Wynand is offline Wynand  South Africa
diyAudio Member
 
Wynand's Avatar
 
Join Date: Mar 2005
Location: Cape Town
Default please help me understand....SPDIF on motherboard.

Right....

I've got a P4M800-M7A motherboard from Biostar. It has a ACL655 audio chip from realtek. On the datasheet of the ACL655 it says it supports 6 channels out, this is verified by the software that gets installed. You can choose whether you want 2 or 6 channels out.

Here comes my problem.

I can't seem to find anywhere where it gets mentioned if all 6 channels will be output on the spdif header and what its enco.

Also, can I tell the PC to decode the data from say, AC3 to PCM and put that out on the spdif?

I'm pasting a list of features from realtek's site to show what it CAN do.


ALC655
AC'97 Rev 2.3 Audio CODEC

General Description
The ALC655 is a 16-bit, full-duplex AC'97 Rev. 2.3 compatible six-channel audio CODEC designed for PC multimedia systems, including host/soft audio and AMR/CNR-based designs.

The ALC655 incorporates proprietary converter technology to meet performance requirements for PC99/2001 systems. The ALC655 CODEC provides three pairs of stereo outputs with 5-bit volume control, a mono output, and multiple stereo and mono inputs, along with flexible mixing, gain, and mute functions to provide a complete integrated audio solution for PCs.

The digital interface circuitry of the ALC655 CODEC operates from a 3.3V power supply for use in notebook and PC applications. An integrated 50mW/20ohm headset audio amplifier for Front-Out and Surround-Out, a 14.318MHz -> 24.576MHz PLL, and a PCBEEP generator cut BOM costs. The ALC655 also supports S/PDIF input and output for easy connection of PCs to consumer electronic products, such as AC3 decoders/speakers and mini-disk devices.

The ALC655 CODEC supports host/soft audio from Intel ICHx chipsets as well as audio controller-based VIA/SIS/ALI/AMD/nVIDIA/ATI chipsets. Bundled Windows series drivers (98/ME/NT/2000/XP), EAX/Direct Sound 3D/ I3DL2/A3D compatible sound effect utilities (supporting Karaoke, 26 types of environment sound emulation, 10-band equalizer), HRTF 3D positional audio and Sensaura™ 3DPA (optional) provide an excellent entertainment package and game experience for PC users. In addition, the ALC655 is embedded with an impedance sensing capability to detect when a device has been connected to input or output jacks.


Features
Meets performance requirements for audio on PC99/2001 systems
Meets Microsoft WHQL/WLP 2.0 audio requirements
16-bit Stereo full-duplex CODEC with 48KHz sampling rate
Compliant with AC'97 Rev 2.3 specifications
Front-Out, Surround-Out, MIC-In and LINE-In Jack Sensing
14.318MHz -> 24.576MHz PLL to eliminate crystal
12.288MHz BITCLK input
Integrated PCBEEP generator to save buzzer
Interrupt capability
Three analog line-level stereo inputs with 5-bit volume control, LINE_IN, CD, AUX
High-quality differential CD input
Two analog line-level mono inputs: PCBEEP, PHONE-IN
Two software selectable MIC inputs
Dedicated Front-MIC input for front panel applications (software selectable)
Boost preamplifier for MIC input
LINE input shared with surround output; MIC input shared with Center and LFE output
Built-in 50mW/20ohm amplifier for both Front-out and Surround-Out
External Amplifier Power Down (EAPD) capability
Power management and enhanced power saving features
Supports Power-Off CD function
Adjustable VREFOUT control
Supports 48KHz S/PDIF output, complying with AC'97 Rev 2.3 specifications
Supports 32K/44.1K/48KHz S/PDIF input
Power support: Digital: 3.3V; Analog: 3.3V/5V
Standard 48-pin LQFP package
EAX™ 1.0 & 2.0 compatible
Direct Sound 3D™ compatible
A3D™ compatible
I3DL2 compatible
HRTF 3D positional audio
Sensaura™ 3DPA enhancement (optional)
10-band software equalizer
Voice cancellation and key shifting in Karaoke mode
AVRack® Media Player
Configuration Panel for improved user convenience
  Reply With Quote
Old 19th July 2006, 06:31 PM   #2
preiter is offline preiter  United States
diyAudio Member
 
preiter's Avatar
 
Join Date: May 2006
More than two channels out on SP/DIF usually means Dolby Digital aka AC3. The problem is that encoding Dolby Digital requires special licensing from Dolby and almost no sound cards that are available support it.

NVidia's NForce2 (but not the later NForce chipsets) and the Mystique are the only sound cards I know of that support Dolby Digital Live (that's what they call realtime DD encoding).

So basicially, unless you buy that one sound card, you are stuck with two channels out of SP/DIF. If you have the correct software, you can use SP/DIF passthru to output DD from sources which are already DD encoded (e.g. DVDs), but I have had trouble getting that to work.
  Reply With Quote
Old 20th July 2006, 08:26 AM   #3
Wynand is offline Wynand  South Africa
diyAudio Member
 
Wynand's Avatar
 
Join Date: Mar 2005
Location: Cape Town
The guy I work for uses a P4 for his multimedia and he uses a on-board soundcard. Using the spdif into a commercial a/v receiver he gets dolby, no problem. The a/v receiver recognized dolby and shows it on the lcd. When he forces the output to PCM, the amp says stereo. Thus I have come to the conclusion that.

1. Buy a commercial a/v receiver ( too expensive ) or
2. Use stereo spdif out or
3. Bugger digital and use the 6 analog outs and don't worry about all the noise on the signal.

Maybe a combo of 2 and 3

SPdif for music and analog for games/movies.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nice motherboard DragonMaster Everything Else 1 4th February 2007 08:02 AM
SPDIF on cdrom to SPDIF on Digi Crossover davidallancole Digital Source 0 11th January 2007 04:26 AM
Asus Motherboard herm Everything Else 5 3rd January 2007 10:11 AM
cdrom spdif quality / sound card spdif metebalci Digital Source 0 2nd September 2006 08:16 PM
PC motherboard - > spdif out mods ? JinMTVT Digital Source 0 16th December 2005 03:50 AM


New To Site? Need Help?

All times are GMT. The time now is 01:37 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2