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Topic: 24 bit capture bugs??

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  1. #1

    24 bit capture bugs??

    My apologies if this has come up before - it sure looks like GSt bugs, and if so, I can\'t believe nobody has noticed them.

    I\'ve just started playing around with capturing 24-bit audio. My sound card is sblive, which can\'t play 24-bit, but I can load the 24-bit files into Cool Edit Pro and it can play and mix them. Problem: More than half of the 24-bit files that I record end up crashing CEPro when it tries to load them.

    I did a little investigating, and it seems that GSt is writing the 24 bit files (some of them) incorrectly. There are definitely incorrect values in the header, and the length of the file definitely isn\'t right. By twiddling the header values around and chopping off 10 bytes at the end (!), I can get CEPro to load the files with a spurious \"Temporary disk full\" message (which is bogus; I have ~7gb free on my temp disks). But at least it loads the files.

    Then, the next problem: when I load up about 4 or more of these files, they are *always* out of synch with each other, sometimes drastically, after about 3 minutes. I don\'t have this problem (at least not often) with 16 bit capture.

    I\'ve got the latest version (I think) of Gst, 2.01.26. Has anybody else noticed these problems? For now, I\'ve given up on 24 bit capture. I sure would like to get those extra bits, though.



  2. #2

    Re: 24 bit capture bugs??

    I used to have the out of sync problems but now I don\'t now that I set Cakewalk properley.I set Cakewalk to output midi start/stop and set giga\'s capture to wait for incoming midi signal.After that I can load the captured wave file(24 bit)into cakewalk or Wavelab no problem.The only problem I have now is that capture recording stops as soon as the midi clip ends so if there\'s any sustaining notes they get cut off.For now I just add a small blank midi clip at the end so capture doesn\'t end as soon as the midi clip does.I suspect that since Cool Edit is not a midi based program it can\'t output start/stop signals,just sync.

  3. #3

    Re: 24 bit capture bugs??

    <BLOCKQUOTE><font size=\"1\" face=\"Verdana, Arial\">quote:</font><HR>Originally posted by Alan:
    I used to have the out of sync problems but now I don\'t now that I set Cakewalk properley.I set Cakewalk to output midi start/stop and set giga\'s capture to wait for incoming midi signal.After that I can load the captured wave file(24 bit)into cakewalk or Wavelab no problem.The only problem I have now is that capture recording stops as soon as the midi clip ends so if there\'s any sustaining notes they get cut off.For now I just add a small blank midi clip at the end so capture doesn\'t end as soon as the midi clip does.I suspect that since Cool Edit is not a midi based program it can\'t output start/stop signals,just sync.<HR></BLOCKQUOTE>

    I\'m doing the midi start/stop thing, and I tack on that little bit of silent midi at the end so it won\'t stop recording too soon.

    CEPro can be run in SMPTE synch mode, but I haven\'t played with that. Doesn\'t seem like I should have to, if the wav\'s get recorded correctly (as they generally are in 16-bit).

    I wonder if I\'d have better results if I had a 24 bit sound card? Could that affect the accuracy of GSt\'s recording?



  4. #4

    Re: 24 bit capture bugs??

    The soundcard does not affect the rendering of sound files to disk. When a sound file is rendered to disk, it is a lot like saving a document in a word processor. GigaStudio figures out what bytes would have been sent to the sound card to represent its sounds, and instead of sending these bytes to a soundcard simply writes they bytes to disk. The only time the sound card is brought into the picture is when it is used to read this rendered file and then make the corresponding sound(s).

  5. #5

    Re: 24 bit capture bugs??

    <BLOCKQUOTE><font size=\"1\" face=\"Verdana, Arial\">quote:</font><HR>Originally posted by wworf:
    The soundcard does not affect the rendering of sound files to disk. When a sound file is rendered to disk, it is a lot like saving a document in a word processor. GigaStudio figures out what bytes would have been sent to the sound card to represent its sounds, and instead of sending these bytes to a soundcard simply writes they bytes to disk. The only time the sound card is brought into the picture is when it is used to read this rendered file and then make the corresponding sound(s).<HR></BLOCKQUOTE>


    That\'s what I thought. That\'s also why I wish GSt had a \"silent capture\" mode that didn\'t bother with audible output at all, just performed all the calculations and wrote the results to disk whenever they\'re ready. No more worries about timing or polyphony, less time spent defragmenting, etc.!

    Any CEPro users out there who have had success with 24 bit capture?


  6. #6

    Re: 24 bit capture bugs??

    This may go under the heading of \"tips and tricks\" - I\'ve got the timing problem resolved with 24 bit capture. After I went back to 16 bit, I started having all kinds of synch problems, all the time! I hadn\'t had that trouble before. So, after noodling around for quite a while, I tracked it down to one difference in the Cakewalk files I was recording: I had removed all the audio tracks from them. After I put a single audio track back in, my captures were all perfectly in synch, in 24 bit as well.

    I guess Cakewalk needs at least one audio track to help it keep time properly. Sure wish I\'d figured that out sooner.....

    I still have to tweak the headers of the 24 bit wav files to keep CoolEdit Pro from crashing - annoying, but liveable.

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