Noob discovers digital distortion the embarrassing way

[hiandy]

Hi y'all, I have mixed down a song from Cubase to hard disk, mastered it in Soundforge and it sounds great when I play it thru any program that uses DirectSound. I found out the file had serious problems when I burnt it to CD and sent it to someone. When I burn it to CD to listen in different music systems or play the file using WaveOut there's all this white noise, or digital distortion that wasn't there before.

The 'Scan Levels' function in the normalise dialog box in Soundforge tells me the peak is 0.0 db and the RMS -18.1 db and I do understand about clipping and such and at no time during the recording/mixing/mastering process did I encounter clipping levels.

The full process was this:

* I use the Audio mixdown function to the tracks in Cubase, using 16 bits at 44.1 Hz (i have also tried 24 bits).

* I then load the file in Soundforge to do some mastering but the problem is already there (ie if I don't do any mastering the distortion is there)

* the thing I don't understand is that there is NO problem when I play the file in ANY software program that uses the DirectSound API instead of the older WaveOut API. Its like there this secret volume information within the file that is missing when you try to play it via a CD (or WaveOut). Window media player handles this by trying to reduce the volume so as not to play any distortion but this sounds very very ugly. And through older CD systems, there's all this crackling white noise thru the music.

* OBVIOUSLY there is something I don't understand which is why this question is being posted in the Noobie section. Is there any more information about the process I'm using that I need to give? Thanks in advance for any help.

Tech details: We use a USB m-audio omnistudio as our computer interface connected to an Athlon 2600 computer running Windows XP.

Edit: in Cubase, the peak level in the Stereo Out bus (which is the source for the mixdown) is -0.9 db which i've tried drastically reducing to no avail

 

[scrubs]

At what bit depth are you recording your tracks (16 or 24)? The process of dithering from 24 to 16 bit adds a small amount of noise, but it would not be noticed by most people, so I doubt that is your problem.

Do you have a soundclip you could post?

 

[hiandy]

hey scrubs, thanks for taking an interest ... to answer your questions

I'm definitely recording in 24 bits - I have the option of mixing down with both 24 bits and 16 and i've tried both. When I read up on dithering I thought mixing down in 24 bits and then converting later to 16 bits was the problem but it's not.

The sample file I've included the URL for below was mixed down in cubase with 16 bits. Maybe that's where the problem is ... but it still doesn't explain things.

If you have a Windows system, play the sample file in both Windows Media Player (WMP), which always uses WaveOut, and some other player that uses DirectSound and not WaveOut, ie Winamp, but make sure you have DirectSound selected in the preferences. You will notice that in WMP when the guitars start to pick up, the volume starts to go haywire with the player trying to prevent the horrible noise you would hear if it was through a crappy stereo system. It'll sound like i've chucked the sound data through a compressor with all the wrong settings.

And then when you play it in Winamp, it sounds fine. Maybe even quite cool if you like super-distorted guitars. If you do and if you're still not impressed, wait for the rest of the song will ya? I promise to upload the full version of my first glorious composition for everyone to hear once this problem is sorted!

If you don't experience the difference in sounds through the different players, then maybe its because I'm using a 24 bit soundcard (Audigy) which maybe is able to correctly read the file, whereas older ones can't. I'm guessing now but just trying to give as much info as possible.

The URL for the sample file is:
http://www.members.iinet.net.au/~hiandy/sample1.zip
- its 1mb in size and the format is mp3 (vbr)

thx for all your help - you'll get a credit in the liner notes for this

 

[hiandy]

nobody's got any comments? Has anyone got any suggestions for other boards I could post this question to ? I've uploaded the sample file ... should I have posted this in the 'Advanced questions' section? I would have thought this was a common noobie mistake ...

 

[dgatwood]

Hi y'all, I have mixed down a song from Cubase to hard disk, mastered it in Soundforge and it sounds great when I play it thru any program that uses DirectSound. I found out the file had serious problems when I burnt it to CD and sent it to someone. When I burn it to CD to listen in different music systems or play the file using WaveOut there's all this white noise, or digital distortion that wasn't there before.

I believe that DirectSound uses floating point representation up to your driver, while WaveOut does a conversion to integer during the software output stage. Sounds like your sound card builds in a little headroom in the conversion from float to integer, so you don't notice that the float value is exceeding +-1.0 slightly.

Bump the level down by a dB or so.