S/PDIF from Recorder to PC without Pops/clicks?

Discussion in 'Recording/Live Sound' started by sws1, Mar 31, 2005.


  1. sws1

    sws1 Member

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    I'm trying to get the audio tracks from my Roland VS890 into my Windows 98 PC running Cakewalk Pro Audio 9.03.

    I have a M-Audio 2496 audio card which has S/PDIF in and out. I also have the Roland and Cakewalk synched to MTC provided by the Roland.

    Everything works 99% good, which, with digital audio SUCKS. The audio that I transfer from the recorder into the PC gets this random pops and clicks in them every 5 secs (more or less). Not a lot, but enough to hear them.

    They are not clipping sounds, as the audio volume is not that high. For whatever reason, something on the PC is not capturing it 100% accurate.

    I can tell it's an issue when I copy FROM Roland to PC as there are no pops on the original audio on the Roland, and when I play back the transferred audio from Cakewalk, the pops are in the exact same spot.

    Does anyway know how to get rid of this? I've tried to adjust every buffer/cache, etc setting I could find in both Cakewalk and the audio card control panel.
     
  2. LSchefman

    LSchefman Supporting Member

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    Have you clocked them to the same source?

    Digital audio transfers must often be clocked, especially where one machine is slaved to the other with timecode. Check and see if there are connections on the gear for hooking up the clock of one to the other, and then slave one of the machines to the other's clock.

    I'm guessing that if you're slaving the computer to the Roland piece via MTC, use the Roland as the master clock.
     
  3. MichaelK

    MichaelK Member

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    I think Les nailed it. Sounds like a clocking issue.
     
  4. sws1

    sws1 Member

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    Isn't that what syncing is?

    I have the Roland as the Master, sending out MTC. Cakewalk is then sent to sync to MTC.

    Maybe I should have it sync to "audio" instead of MTC. I might have tried that. (I think I pushed every g-damn button on that program.)
     
  5. muddy

    muddy Member

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    no, sync is for midi (midiclock), which is not the same as wordclock. clicks & pops are usually the byproduct of jitter, which happens when the wordclock source isn't that great. you lock a converter to a better clock or wordclock generator by either the s/pdif (using a good converter's clock) or the bnc connection for wordclock in to a good wc generator.


    ml
     
  6. Chiba

    Chiba Gold Supporting Member

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    Yeah - what they said :) I had the same problem with some ADAT transfers I was doing til I wordclocked everything up right. Suddenly, no clicks!

    --chiba
     
  7. MichaelK

    MichaelK Member

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    >> you lock a converter to a better clock or wordclock generator by either the s/pdif (using a good converter's clock) or the bnc connection for wordclock in to a good wc generator.

    You probably don't need a better clock source to solve your clicks. Your problem is apparently that you have two working at the same time. All they need to make a "click" is to be off from one another by one little sample every now and then. Most likely you just need to slave one to the other and the clicks will disappear.

    If you can select an external clock source in one of your devices you can probably slave it to the other's clock. If your MAudio drivers or DAW software allows you to select SPDIF as the clock source instead of the internal clock of your computer, everything should sync up. Or maybe the Roland can slave to your computer. But not being familiar with either device or with Cakewalk, I'm not sure how it's done or if it's possible.

    It's preferable to use the better clock source as the master... in this case, my guess would be the Roland.
     
  8. muddy

    muddy Member

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    also, in case you weren't aware, you don't lose the use of your s/pdif should you use it to lock to the connected device's clock. it still functions as a digital output.


    ml
     
  9. LSchefman

    LSchefman Supporting Member

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    >>Isn't that what syncing is<<

    No, as others have pointed out.

    Syncing is using Time Code - SMPTE or MIDI time code - to have two machines start, synchronize and stop their "transports" (a holdover from analog days) at the same time. So, for example, if you started all your audio tracks at 1:00:00:00 on one machine, and wanted all the transferred tracks to start at 1:00:00:00, you'd be able to do that.

    But the smallest subdivision of time code is one frame. One frame means one frame of video. Time Code was originally used to sync audio tracks to picture. One frame = 1/30th of a second (or 1/29.97th of a second if it's drop-frame video you're syncing to).

    As you can imagine, in 1/30th of a second, there are literally thousands of samples firing away in digital audio.

    The way to sync digital audio to sample-accuracy, so that everything is in phase, doesn't click or pop, etc., is to have both digital clocks running at the same micro-speed, and ideally, to use the same clock as the master.

    Hope this explanation helps. :)
     
  10. sws1

    sws1 Member

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    I did check my setup. The audio card is getting the timing from the Roland.

    I suspect the issue is with Cakewalk struggling to keep up with the audio coming in.

    I've never had a problem when recording analog into the card like with a guitar. But now, when going digital, I'm getting the pops.
     
  11. GuitslingerTim

    GuitslingerTim Member

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    The issue is a lack of wordclock which is a necessary feature for digital transfers.

    When two devices are linked through wordclock the sample rate is consistent from device to device, but you only need that if recording in realtime is a necessity.

    Why don't you save your files to disk using the Roland and then load them from disk into Pro-Audio? If PA lacks the features you need (never used it) upgrading to Sonar4 is affordable--$149.
     
  12. sws1

    sws1 Member

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    I found a workaround. I can burn 2 tracks at a time to CD-RW from the Roland. Then rip them into a stereo WAV file on the PC. Then import them into Cakewalk, splitting into 2 tracks. Very tedious and slow since burning the CD takes 10 mins, but at least it is pop free.

    I'd like to upgrade the software, but I have an older Win98 machine with PA 9 and lots of plug ins. I'm afraid that if I get a new machine, I won't be able to use all the DirectX plugins on Win XP.

    Do you know if that is possible?
     

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