Latest post Tue, Apr 24 2012 7:40 PM by M-Edit. 10 replies.
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  • Mon, Apr 23 2012 5:02 PM

    Audio out of sync when making quicktime reference files in HD from Avid DS

    AVID DS Nitris 10.1

    I am trying to make quicktime reference files from avid ds to take into mpeg streamclip. However I have discovered that every quicktime reference file I make from an HD project has an audio sync issue. The audio goes out of sync with the video within a few seconds into playback.

    On a side note I do not have this problem when making quicktime refs from SD projects.

    Any ideas?

  • Mon, Apr 23 2012 7:08 PM In reply to

    • slabross
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    The Quicktime reference embeds the audio in the file but the video is reading from the media storage source. Reading SD media is relatively easy but I wonder if the Quicktime player is not experiencing a lag while trying to decode the high definition video material?

    Also, could it be the frame rate that differs between audio and video?

    Sylvain Labrosse
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  • Mon, Apr 23 2012 7:34 PM In reply to

    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    You bring up some great points.  The video is transcoded mxf files as well not sure if that may be causing the lag.  I would really like to find a solution as I am needing to make quicktimes for webcasts and streaming more and more and mpeg streamclip is a much better interface. 

    There are no settings or anything I can seem to do on my end in avid to combat this.

    The only thing I found was someone mentioned quicktime's latency setting of 33 and to reset it to 0.0001 under edit/preferences/quicktime/audio in quicktime.

    This did not help my problem.

    Any advice as to what to try next?

     

  • Mon, Apr 23 2012 7:51 PM In reply to

    • slabross
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    I guess I did not understood you properly...

    The audio and video offset is not just happening as you play the Quicktime file in a player but it is written this way by the streaming application. So the final encoded file contains the offset, is this correct?

    If true, no solution comes to my mind as I fail to understand why the embedded audio in the Quicktime reference would be "off" from its linked video stream. Unless your encoding software creates the offset?

    You mention using version 10.1. Is this correct? In any case, that release uses a 32-bit DsComServer component to handle Quicktime files and the current 10.5.2 release uses a QTDecoder component and newer Quicktime API. It is possible that you are facing a problem that is no longer present in the product.

    Sylvain Labrosse
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  • Mon, Apr 23 2012 8:33 PM In reply to

    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    Yes the encoded file contains the sync issue in every file made from an HD quicktime reference file. 

    I was afraid of what you are saying about the version we are using as we are a PBS station on a tight budget and I don't see us upgrading anytime soon.

     

  • Tue, Apr 24 2012 5:56 AM In reply to

    • M-Edit
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    Hmmm, there's been a lot of gamma and level anomalies,
    and still are in certain areas, going through versions 10.0-10.5
    but I've never encountered synch issues like the ones you're
    mentioning.

    And of course an out-of-sync situation in a playback situation
    can be something that's hardware/software dependent, because
    the hardware/software combination used for playback might just
    not cope with the bitrates that's needed for smooth playback and
    starts skipping frames resulting in all kinds of strange problems.

    But in a software coding situation I wouldn't expect that the
    hardware or software shouldn't be able to "keep up with it".
    Then I would expect it to be a "misreading" or "mis-interpretation"
    of the info stored in the Qt Ref file. But then again, what would be
    the difference in a QT Ref from an SD export and a HD export?
    And is there a difference? Well, I dont know.

    Anyway, some questions.

    Have you imported the HD QT Ref file back into the DS to see
    if this give an out-of-sync issue also? If this gives the same
    result as coding via MPEG Streamclip, then you're in for a
    treat, but if not...

    Have you tried coding in another application, just to see what happens?

    Is the audio out-of-sync from the very beginning of the coded file
    or did you say that it first happens a couple of seconds in?

    And is it just a couple of frames off or are we talking seconds?

    When out-of-sync, is it a constant or does it drift?

    What format are you coding to?

    Quicktime and MP4's using B-frames often give a couple of frames
    out-of-sync when played back in Quicktime player but might be
    okey when played back by for example the VLC Player.

    But that just a couple of frames off.

    Well, there's a couple of questions for you. Wink

    //mike

  • Tue, Apr 24 2012 2:01 PM In reply to

    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    Well first off the quicktime ref seems to slip slowly out of sync.  It starts in sync and within a minute into the program is about 4 seconds out of sync. 

    Secondly when I try to reimport the REF file the avid simply gave me an error.

    I have tried encoding with mpeg streamclip and it seems pointless to try encoding with other software while the quicktime ref file itself remains out of sync.

  • Tue, Apr 24 2012 2:53 PM In reply to

    • M-Edit
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    jnicholson1437:
    ...it seems pointless to try encoding with
    other software while the quicktime ref file itself remains out of sync.

    Of course, that was only an option if the re-import into the DS was okey.

    So what exactly is the error that DS throws up on import?

    Can you maybe make a screendump or use the "Message Grabber" tool
    to pass along the information from that or those error-dialogs?

    //mike

  • Tue, Apr 24 2012 4:34 PM In reply to

    • slabross
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    jnicholson1437:

    ... the quicktime ref seems to slip slowly out of sync.  It starts in sync and within a minute into the program is about 4 seconds out of sync.

    Then, there is a 29.97 versus 30 fps frame rate difference between video and audio that requires a 1.001 adjustment, and that can be achieved in the DS Media Tool. Display your audio media list, right click and click up / down convert audio.....

    Refer to the Online Help for more information.

    Sylvain Labrosse
    Principal Expert | Services and Customer Success

    Avid
    3510 St-Laurent Boulevard
    Montréal, QC H2X 2V2
    Canada
    sylvain.labrosse@avid.com

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  • Tue, Apr 24 2012 5:56 PM In reply to

    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    I hope I didn't come off like a jerk...didnt mean too. I just dont have any options for putting this into other software until I get the reference problem sorted out.  And you are correct IF I could have brought the quicktime ref back into the avid and it was syncing properly that would be a different story. I get the error message "One or more errors were detected while importing "filename"."

    I was however able to get the quicktime ref to import into media composer on the same machine.  It came in and the audio gradually slipped out of sync on it as well.  So this problem is getting more confusing.

    I simply cannot get past the quicktime issue with the audio delay.  And on top of that I cant seem to make a simple H264 quicktime out of the avid without getting a read write error message in the middle of the file processing. 

    I have tried making a quicktime AVI uncompressed and recieved the same read write message.

     

  • Tue, Apr 24 2012 7:40 PM In reply to

    • M-Edit
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    Re: Audio out of sync when making quicktime reference files in HD from Avid DS

    Okey, another round of questions.

    What is the exact error message when you get to "the middle of file processing?

    And by "quicktime AVI uncompressed" you really mean "AVI uncompressed", right?
    Quicktime and AVI are TWO different beasts of video/audio containers.

    Have you tried outputting an "un-compressed" Quicktime Animation coded file?
    It will be a really BIG file but just for the sake of seeing what happens
    when MPEG Streamclip try to code it.

    Settings: (which makes it transparent, i.e. equal to uncompressed)

    Depth: Millons of Colors
    Quality: Best

    And again, what format are you trying to output from MPEG Streamclip?

    And also, why are you coding a h264 directly from the DS?

    So here's a question to Sylvain (and possibly Dermot).
    Where you really able to output a decent h264 QT directly from DS v10.1?

    I can't remember that I even tried, but then again,
    which says nothing really?

    //mike

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