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Optimod PC-1101/Opticodec Audio Glitch Issue

B

bigtom101

Corporate just had us change our streaming box over to one with a Optmod PC card and Opticodec - but the encoded audio has a weird glitch to it. It doesn't drop out, but it has a weird "flutter" to it that isn't there on the output of the card...only on the stream audio. Checked input and output levels, all ok and distortion free.

The flutter is not there during quiet passages - it changes sound depending on the intensity of the program material. Here is a Dropbox link to a sample of the audio - https://dl.dropbox.com/u/14667252/glitchy_audio.wav

Any ideas? Danke schoen!
 
Do you offer full bandwith to the Opticodec or just 40-15k?
Is max audiolevel at 0dBFS or is there a bit of headroom left?
 
richard.vanderveen said:
This might be a stupid question considering your sample, but is the source lineair (all the way uncompressed)?
Click to expand...

Nope...audio is on automation as MP2, and we have satellite programming that is non linear.
 
I'm no expert, but to me it sounds like cascading compression Algorithms. If it is, there's really no other solution than cranking up the quality of the sourcematerial...
I know, not too much you can do about satellitefeeds. Also remember that bitrate only tells half the story (or less...).

You could try another encoder to see if there is a noticable difference, but I doubt it, the opticodec is pretty good.

Anyone wants to chime in on this?
 
Not exactly easy to use linear PCM all the way when you're taking feeds off the bird.

If it's talk, then the best thing to do is roll off the highs at 10k before it hits the codec. Nobody will notice with all talk programming and it cuts down on the artifacts.
 
Or, even better, back down the encoder sample rate to 32 or 24 kHz first. Then do as WNTI says if needed - even a very gentle roll-off can make a big difference.

Even for music don't use a sample rate greater than 32 kHz going into the codec.

WNTIRadio said:
Not exactly easy to use linear PCM all the way when you're taking feeds off the bird.

If it's talk, then the best thing to do is roll off the highs at 10k before it hits the codec. Nobody will notice with all talk programming and it cuts down on the artifacts.
Click to expand...
 
Ah ha! The problem? The box was running Windows 7 - put XP on, and suddenly the glitching is gone! Must have been a compatibility issue with the 7 audio drivers.

Thank you for all of the help!
 
Turnpike Tuner said:
Ah ha! The problem? The box was running Windows 7 - put XP on, and suddenly the glitching is gone! Must have been a compatibility issue with the 7 audio drivers.

Thank you for all of the help!
Click to expand...
'downgrading' a 7 box to XP is something I'm considering doing to one of the walmart discounted acer machines I've recently seen.

How is this done?
 
Just find an old XP disc and load it on there, then do the updates. There has got to be an XP disc laying around your station...
 
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