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FAQ
Frequently Asked Questions
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What are the disadvantages of using the driver?If you're a gamer, you won't be a able to enable EAX effects - however, regular multi-channel 3D sound is still possible. If you plan to use the analog ports, you should look for another card - the analog parts (ADC, DAC) of the C-Media chip are pretty bad. If you have a card with a 8768+/8770 chip, you'll lose the Dolby Digital Live feature. What are the advantages of the using the driver?This driver is completely bloat-free (e.g. no annoying tray icon), small (100kB), fast (due to the lack of sound processing) and stable. Features not seen in all the official drivers such as true 16 bit output and correct ac3/dts passthrough over the digital ports (coaxial, TOSLink) are fully implemented. Furthermore, it supports bitperfect playback and two additional sample rates (88.2 kHz, 96 kHz). The driver runs on all the major Windows flavors (including the Media Center Edition/MCE and 64 bit systems) and the source code is fully available. Thus it's especially well suited for HTPCs. Is the driver compatible with AC97/HDA chips such as C-Media 9738/9739/9880L?No. All USB devices from C-Media are incompatible, too. What is S/PDIF?S/PDIF is basically a standard which defines an interface for transmitting audio signals digitally without loss. This interface basically supports two kinds of formats:
A limitation of the S/PDIF is that it can carry no more than two uncompressed PCM audio channels - multi-channel has to be compressed beforehand. Due to bandwidth constraints, newer formats found on Bluray and HD-DVD media such as Dolby TrueHD or DTS-HD can't also be transmitted over SPDIF. The S/PDIF signal can be transmitted optically through TOSLink (LED sender -> plastic optical fiber -> receiver) and/or electrically through RCA/coaxial cable. Optical transmission has the advantage that it's galvanically isolated and that it isn't susceptible to crosstalk (noise induction from other lines) and ground loops, so it's preferable over a coaxial cable in most cases. What's the recommended setting for the speaker configuration?The capability to pass through a multi-channel AC3/dts signal is unaffected by this setting. For having a S/PDIF signal during music playback, the "2.0 Stereo" setting is recommended assuming that the soundcard is digitally connected to the receiver/amplifier (TOSLink/coax cable). The driver model of Windows has unfortunately quite a few design flaws. A major one is that a driver has no way to determine whether an application wants to play a 5.1 PCM sound (e.g. some game) or just plain stereo sound (e.g. WinAMP). If the speaker configuration is set to 5.1, all sources are considered to be 5.1 and the digital ports are turned off. Why do I get only stereo sound when playing DVDs?In all likelihood, there are some configuration issues causing this. Here are some hints:
What is Dolby Digital Live?Dolby Digital Live is a marketing term coined for the capability to encode multi-channel audio data to AC3/dts on the fly. This is a pretty bad idea because there's quite a nasty quality loss in the process (transcoding and low bit rates), it requires computational effort (resulting in a significant frame rate drop) and it's still bug ridden. There are a handful of cmedia chips which support DDL with the help of the official drivers, but unlike NVidia's Soundstorm, it's entirely software based - there is no hardware acceleration. Consequently there's no implementation for Dolby Digital Live in this driver. How do I install the driver in 64 bit edition of Vista?Currently, the only way to run the driver after installing these updates is by pressing F8 during boot-up and disabling the enforced driver signing or by installing the linked tool. You have to enable test signing with the tool. Each time you've installed the driver, it needs to be test-signed after the installation. I tried to load the driver, but my system crashed. How can I recover?There are two possible causes:
How do I enable ac3/dts passthrough in my player software?The so called "passthrough mode" enables preencoded ac3/dts/wma pro streams to be transmitted to your receiver. Such streams can often be found on DVDs, in AVIs/MKVs or other digital media. WinDVDStart WinDVD, right-click somewhere in the video window and select 'Setup...'. Then go to the audio tab and select "Digital S/PDIF Out to External Processor". PowerDVDStart PowerDVD, right-click somewhere in the video window and select 'Configuration...'. Then go to the audio tab and select the "Use SPDIF" entry from the 'Speaker Environment' box. Media Player ClassicOpen Media Player Classic and open the 'Options' window ('View' -> 'Options' or just press the O key). Select the 'Internal Filters' node from the tree on the left and double click the 'AC3' entry in the 'Transform Filters' list. Choose "SPDIF" in the window and click "OK". AC3FilterClick Start, Programs, AC3Filter and then "AC3Filter Config". Check the "Use SPDIF" box. ffdshowInstall the latest version of ffdshow. Click Start, Programs, ffdshow, "Audio decoder configuration". Click "codecs" in the left panel and select "S/PDIF" from the drop down menus both for AC3 and dts. vlcvlc contains a bug that results in stuttering audio playback when ac3/dts passthrough is enabled. In the most current version of vlc, there is a way to circumvent this bug: set the output module to "WaveOut", save the settings and restart vlc. How do I enable ac3/dts passthrough in Windows Vista x64?If you are using the WaveRT version of the driver, it should work out of the box with the standard x86 codecs. If you're using the non-WaveRT version, you need to upgrade to the x64 versions of both the player software and the codecs. When using x86 codecs / software, there are problems with passthrough which are caused by a bug in Vista's x86 compatibility layer. Here are x64 builds of ffdshow, and x64 binaries for Media Player Classic are available here. Update: This issue has been fixed with Vista SP1 (build 6001). How do I check if the driver has been installed correctly?Open the device manager (Start -> Run -> devmgmt.msc) and open the 'Sound, video and game controllers' leaf. If the driver has been loaded successfully, there should be a node with exactly the name "CMI8738/8768 Wave Audio Device". Also, the 'CMI8738/8768 Control Panel' should load and display version information in the 'About'-tab. Do I need the Windows Driver Development Kit (WinDDK) for running this driver?No. Precompiled binaries are available in all flavors on the download page. However, if you plan to modify the source code and/or to recompile the binaries from the source, you need the WinDDK - it contains all the vital headers, libraries and a compiler for generating proper sys files. What are the command line options for cmicontrol.exe?Start cmicontrol.exe with the parameter "-h" to get a full list of the parameters. Why doesn't my receiver play sounds when I connect it digitally to the soundcard?There are four possible causes:
Why can't I record sounds from the microphone/line-in/aux input?Most likely, the "Enable S/PDIF-in recording" box in the second tab of the control panel applet is checked - untick it, click "Apply" and restart the recording application. Why does a message box with the title "CreateFile()" and the text "The system cannot find the file specified." pop up when I try to start the control panel applet / cmicontrol.exe?Make sure that the driver has been installed correctly. If you are using Vista, this might be caused by a bug of the operating system. There's a workaround however: close every application which might use the soundcard (browser, winamp etc.), open up the device manager and select the "CMI8738/8768 Wave Audio Device" leaf. Right-click this leaf and select "Uninstall". A window will pop up asking for confirmation - in that window, tick the box "Delete the driver software for this device" and click "OK". Then, click the "Action" menu and select "Scan for hardware changes". If a suitable driver is now found in Vista's driver repository, it will be installed. Repeat the process until Vista can't find a driver anymore, then install the open source driver. The control panel applet should now work. How can I get multi-channel sound when playing stereo music?The driver has been specifically designed not to process any sound that passes through it. It therefore doesn't upmix stereo sources to multiple channels by itself. For doing this, you can choose from a variety of plugins for favourite music player which give you control over the upmixing process, e.g. Foobar, Winamp, generic DirectSound. After upgrading from the WaveRT version to the non-WaveRT version, sound playback doesn't work anymore. How can I resolve this?This is actually caused by a bug in Vista: the registry entry associated to the driver isn't reset properly during a driver update. This annoyance can be circumvented by doing the procedure which is described in the question above. Why doesn't the "Master Mute" control work?The hardware doesn't have such a control. Unfortunately, there is some software which requires the presence of such a switch, so a fake switch has been implemented. In the "official" driver from C-Media, the control is emulated in software. Why does playback/recording fail when using WASAPI?WASAPI requires Windows Vista and the WaveRT version. Also, only 65536 bytes respectively samples can be addressed by the hardware so the size of the buffer needs to be lower or equal than this value. |
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The command to disable the driver integrity check wasn't working for me, so I found this other command:
bcdedit.exe –set nointegritychecks ON
Anyways...it's working fine now in my Vista 64 bits. Thanks and congratulations!
I'd prefer if you don't post links to pages which distribute illegal software. Also, I've tested DDISABLE_INTEGRITY_CHECKS with the virgin version of vista64 and it worked.
Various DVB-T and DVB-S players would crash with the standard C-media drivers (NMI parity errors etc), the drivers from this site will resolve all of those issues. Brilliant work :)
What format of encoded S/PDIF streams can be forwarded? Are the new "HD" surround formats introduced with BluRay? supported (DD+, TrueHD, DTS-HD Master Audio)? Can any sample rates (192KHz/24bit) be forwarded?
Basically all the standard formats are supported including AC3 and dts at sample rates up to 96 kHz. "HD" formats have a bitrate which is too high for S/PDIF - this is a hardware limitation which the driver can't overcome.
Dogber,
Sorry mate, just to confirm ... I'm using Vista 32bit home edition. Just ordered my c-media soundcard.
I'm an audiophile looking to simply pass a bit perfect output to my external DAC via SPDIF.
Setting the sample rate to 44khz - is anything tampering with the signal at all - is it really simply bit perfect output ?
I guess perfect output is not possible using Vista Media centre but any program that support exclusive mode / ASIO etc etc will work. ?
Regards,
Matt.
Matt, this wiki entry should make some things clearer: http://code.google.com/p/cmediadrivers/wiki/Bitperfect
Is it possible to control the master volume with this driver? E.g. Bitperfect and S/PDIF output. Need to connect a DIY DAC system and power amplifer directly to the S/PDIF output and need to know if I am still able to control the volume from my MS remote?
Regards Benny
Hi Benny,
the hardware lacks such a control and hence it isn't implemented. You have to route the volume keys of your remote control to the Wave mixer.
Regards, dogbert
Thank you for the answer Dogber
Need to understand this ;)
Do you mean that the master volume will not control the "volume" of the S/PDIF output but the wave slider control will?
Need a way to control the volume because a 250 Watt power amp connected directly to the DAC output will blow me away and I do not like to add extra logic to control this as the logic is already implemented in windows and controlled by the remote - do not like to make an extra remote to control the volume alone in the DAC unit.
Regards Benny
correct: for regular PCM sound, the wave slider adjust the volume. for ac3/dts which is passed through to the DAC, this isn't possible, but you're probably interested in PCM only.
Hi, I seem to be having trouble playing sound through 5.1 channels when playing a few games with this driver (AC3/DTS passthrough works perfect though). Using onboard audio, i used to get 5.1 channel surround sound fine but I recently got a new sound card (trust 5250) and the sound is 2.1 now for certain games. Is there anything in particular i should check in the settings? I dont think this has anything to do with EAX as in one game, a sound option is '3D audio without EAX' and this still gives me 2.1 sound.
Thanks
Hi, I would like to know what the changes are in version 1.2.2 compared to the version of August 2008.
Also I would like to know if you are planning to inplant a 'stereomix' option for recording 'wave' sound.
Kind regards,
Michel
lsmith321, there isn't a realtime ac3/dts encoder in the driver, hence multi-channel sound from games can only be transmitted over the analog ports of the soundcard.
michel, thanks for the remainder, I forgot to update the wiki page. The stereomix feature requires some time for implementation and I'm a bit stuffed at the moment, so it's probably not going to happen in the next two months, but it's still on my TODO list.
Hi dogbert,
First of all thanks for your great driver (I used it about a year with WinXp32? an it worked perfectly).
Now I've got problems using it with Vista x64 - installing by .exe and .inf (not supported) fails for both the wavert and the normal version, even if I follow the way I'm told in the faq above (CM_Reenumerate DevMode?(): " Der Vorgang wurde erfolgreich beendet", afterwards a blank window "install driver()").
Any ideas how to fix that?
Yes: run the installer as administrator.
I did so when the error occured....
then please open an issue in the tracker with a few screenshots which describe how exactly you start the installer
Is it possible to record from WaveOut??
BenLaserlove?, that's a feature that's quite nasty to implement, so I haven't bothered yet.
I have finally got it work by the : bcdedit.exe -set loadoptions DDISABLE_INTEGRITY_CHECKS
Works great! Thank you so much!
I have a Diamond Xtreme Sound 7.1 running Windows 7 RC 64-bit and I've tried all of the above, non of which has worked. I've also tried to use both WRT and Non-WRT versions. I am dual booting Vista Ultimate 64-bit and the driver works for this OS. In Windows 7, I will get a message saying driver installed successfully. Also in Device Manager it will look as if everything is fine, but the speaker icon in the lower right hand corner displays an "X". Hence, when this driver is installed, I have no sound via Optical nor line-in output. As of now, I have installed the official (snicker) Cmedia driver from which I can obtain sound from the line-in speakers. Again, in Vista your driver works fine and I love it. Is there anything else I can do in Windows 7?
Using the instructions at: http://www.techspot.com/vb/topic127187.html
I got the CM8738 driver installed just fine under Windows 7. Needs a little effort but it's worth having SPDIF working simultanious with the Stereo Jack out again.
This whole effort has fixed the final and only issue i was having with Windows 7 RC1 7100.
Many thanks to all that have worked on this.
After many months of headaches getting the on-board Realtek audio of the Asus mainboard in my Mediaportal HTPC to do reliable spdif passthrough I bought myself a Trust SC-5250 card, installed the cmedia drivers and never looked back. The card only cost 26 euros and it even came with an optical cable.
This thing rocks! I can now pass-through 44.1 and 48Khz stuff, AC3, DTS, all bitperfect. No more need for asio4all, no more need to manually switch between 41 and 48, no more need for AC3filter to re-encode stuff to 41. I can just play anything and it simply works. I could not be happier. As far as the audio side of things is concerned, I have reached my holy grail on the HTPC.
Dogber, you are a true hero!
Just downloaded your drivers and the driver signing thing, and my Trust SC-5200 seems to work great....EXCEPT: The rear speakers (5.1 configuration) don;t seem to work at all. I have a 3-jack Dell 5.1 system, so need to plug 3 jacks into 3 stereo channels. I think this card uses the line-in as the rear-out. I've tried enabling "Route rear to line-in" i nthe control app, but to no avail.
Any thoughts?
Running Windows 7 RC x64.
Cheers!
On your Trust SC-5200, there's a pair of jumpers which route either the line-in or the rear speakers to a jack - you probably have them configured for line-in right now.
I can't see any jumpers apart from the 6-pin block for swapping C/LFE and rear L/R to LFE/C and rear R/L (i.e. changing the left to right and centre to sub). There's an unmarked 2-pin jumper (J11) and a pin-less 6-block, but nothing obvious to determine whether the jack is line-in or rear out. The manual from the website seems to imply there's no jumper for this either.
Please help, else I'll have to buy a new card (and it looks like it might be a Creative! Yuck!)
Cheers.
Also, in XP (32-bit) on the same PC (dual boot config whiel I test 7), the rear speakers work fine once I go into the Cmedia mixer and enable 6-speaker setup. So I know the hardware is setup fine - it must be a software thingie somewhere.
Any thoughts please?
Cheers for all the hard work on these drivers.
Ian, you're right about the jumpers and the software bug.
Can you please do the following: 1. boot XP and install WPCREDIT 2. setup your card for 5.1 and play something, making sure that all the speakers work as expected 3. start WPCREDIT, select your soundcard (13f6:0100 usually) and make a screenshot of the window containing the i/o registers. 4. send me the screenshot - my email is listed above.
cheers!
Screenshot is at
- can;t find your email address.
Cheers - sorry for the delay.
ian, thanks for the screenshot. unfortunately, I need some more information: I'd like you to do the same thing with ACMEDiag ( http://sites.google.com/site/dogber1/Home/AcmeDiag.zip ) and a data width of 32 bit once again, please.
Hi Dogber1,
I have a 3D Club Agrippa with CMI8770 chipset. Due to your supportet devices page I tried your driver which installed ok showing cmi8738/8768 audio device at the hardware devices window. The old cmi control panel disapperead as described by you. But I even couldn't start it via the command line as described in the faq - it was all gone. So no settings could be made.
The driver itself seems to work fine despite of the rear channels on dts audio. The rears were there when watching dts video, but vanished when listening to dts music. I have my sound card connected via optical cable to my av-receiver.
My main problem is: I run a htpc with mediaportal. Everything works fine despite dts music. I have dts when watching video, but no surround when listening to dts wavs. In the control panel of my 8770 is an option for this Dolby Live thingy. With this option enabled I have surround with dts music (using foobar 8.3 as external audio player for mediaportal), but then also all my stereo files are played back as surrounds (which I really hate). And I have to change this dolby live option everytime by hand if I want to listen to dts audio.
So I hoped your driver would help me with this issue, but unfortunately it didn't (as described above). I don't know if it has something to do with the settings of the cmi control panel (which is gone after installing your drivers), or if your driver doesn't work as intended with the 8770 chipset.
Any suggestions on this?
best regards Roede
Hi Dogber1,
I have followed your development over the years starting with XP MCE, Vista and now finally Win 7. I use this for a full blown media center used for everything by the whole family. I got the retail release of Windows 7 Ultimate 32bit and thought I'd try you drivers on this build. Not getting sample rate switching on the SPDIF output, whatever I set the default to eg 16bit/48Khz this is always output regardless of music or TV. Obviously all the options are ticked in the control panel utility. I've tried both WaveRT and Non versions with the same results. I also had an issue a couple of times with media center using the WaveRT driver saying cannot play a recorded TV file as all the files needed (usually codecs) are not installed. Reverted back the onboard Realtek and all works fine. Any ideas? Cheers, Simon
simonsifi, dynamic sample rate switching is a thing of the past since Vista. the only way to get this capability back is by circumventing the audio service (kernel streaming, exclusive wasapi etc.).
Hi Dogber1 - thanks for the answer, I already suspected dynamic sample rate was not going to happen due to many other posts I've read.
- I want to use bitperfect output for Media Center - don't suppose you know any other method? - I've found an ASIO plugin for WMP http://sourceforge.net/projects/asiowmpplg but that doesn't work quite properly yet - Are there any advantages on using your driver over onboard realtek HD for SPDIF output now since Vista/Win 7 audio stack rewritten, bearing in mind you last response? - Do you know if the Vista/Win 7 audio resampler quality is like - I've read posts suggesting it is high quality ?
Again thanks for your help and work, Cheers, Simon
simonsifi, the realtek hd driver will probably do some extra processing which you can avoid when using my driver. The vista/7 resampler has indeed a much better quality than the one from XP/2k - it's not the limiting factor for the vast majority of setups.
I get the "system cannot find the file" when trying to open control panel applet using XP SP3 through control panel. When I close, it says "get driver data, operation completed successfully. I lost the original install CD for the sound card, and ever since the rear speakers don't work. Any thoughts? Thanks Jim
jim, please have a look at this page.
I've got to tell you, I'm not as computer literate as most of these people, I see your response for Vista, but not for XP. When I try to open the file and see operation completed successfully, cmi comtrol panel opens for a split second, then disappears.Your telling me my answer is here, but where exactly? By the way, the driver installed fine and sounds very good. I've looked this page over several times by now.
jim, basically, there is another driver installed than the one from this site. the driver installation business is unfortunately rather messy in Windows - I suggest you try the procedure to remove all drivers for the soundcard which is described for Vista. This should also work for XP.
Thanks, I'll give it a try
Hi
Do any of the settings, in CMICONTROL or Device Manager properties for the card, affect bitperfectness in Windows XP?
In particular;
CMICONTROL.exe;
Analog- Enable PCM DAC
Digital - Enable copyright bit
Formats - PCM, Mutli-Chanel PCM, Dolby (AC3)/DTS
Device Manager properties;
Audio Devices - Use audio features on this devices
Audio Devices - Do not map through this device
MIDI Devices and Instruments - Use MIDI features on this device
Mixer Devices - Use mixer features on this device
Finally, regarding setting "Enable 5V signal levels" in CMICONTROL.exe, is the "off" setting 3.3V?
Thank you
Oli
oli, only the format tab has an effect: basically, when you disallow formats, the kmixer is forced to resample when a file of such a format is being played.
Brilliant, thank you dogber1. I can rest easy!
Dogber1,
One question:
I am using a Terratec Aureon 5.1 sc. Have you got any idea if I can use spdif out in combination with normal analog audio?
edit? I now have it working with 2 soundcards, which is suboptimal I guess
additional question: if I would turn off my receiver (to which the TOS link is going), will the analog output come into play automatically?
Hi Dogber1,
I'd like to know if it possible to play 192khz/24bits flac files with those drivers ?
With windows XP I must use Asio4all with foobar 2000 to have bitperfect with 44,1khz/16 bits files. But with 192khz/24bits files, i must use the directsound device to play them so i am loosing bitperfect.
Thank you
Philippe
Dogber1,
I have a signal on analog output when line input is connected. I checked "Enable S/PDIF-out" on, but signal from line input is not there, I cannot get anything from SPDIF. Is it how it is supposed to be or I've done something wrong?
Thanks!
Sergey, please check the speaker configuration - it has to be stereo for spdif to work.
Yes, it's stereo. Actually, SPDIF is working, if I play mp3 or something - it works. What I wanted is to mix signals from mp3 and from line or microphone. I can get it on analog output, but for some reason not on SPDIF. :( Thanks!
Sergey, you're right - the ADC is only enabled when you record things so all the analog inputs are not mixed with the digital sound by default. There are some ways to work around this in software, but it's messy.
Müssen die Originaltreiber erst deinstalliert werden? Und bei Onboardsound dieser erst deaktiviert werden?