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[Known Issue] Recording from Stage file is playing back at quadruple the speed



  • When recording stage the playback of the file created seems to be double/triple/quadruple? the speed. What settings should I look at to troubleshoot the culprit? Currently using AVI / HAP and I'm on a PC. FPS are 29.97 in all locations



  • example of output here: https://drive.google.com/file/...


  • Tech Staff

    I have seen this issue, and have recorded it to our bug tracker. 
    I found that it only occurred with 'some' hap codecs... so you could try the others, however, recording to Hap isn't recommended as its is rather CPU heavy, and this may be why the speed isn't correct (frames may drop if not compressed in time).
    Some of the other Microsoft codecs are better (less cpu intense).
    BUT, during my tests I found that the best codecs for recording and playback were the BlackMagic codecs installed when you install the 'Desktop Video 11.x' software.
    These BM codecs were among the lowest cpu usage of all my testing, and provided a quality image.

    You can get the Desktop Video package at: https://www.blackmagicdesign.c...



  • @dusx said:

    I found that it only occurred with 'some' hap codecs... so you could try the others, however, recording to Hap isn't recommended as its is rather CPU heavy, and this may be why the speed isn't correct (frames may drop if not compressed in time).

     @callie 

    Certainly this is a bug and we will fix it as soon as we can manage. However, it simply comes down to this: compressing a HAP frame generally takes way longer than a the the frame time to accomplish. In other words, if you're running at Isadora at 30fps the frame time is 1/30 = 0.033 seconds. If it takes 0.1 seconds to compress a frame, then 0.1 / 0.33 = approx 3 Isadora frames will pass before the next frame is compressed. Isadora should realize this and insert 3 frames of the same material, but instead it inserts 1 and when it plays back it's too fast. In the end, HAP is not a good codec for real time capture.

    That's why @DusX is recommending the Blackmagic codecs, as they take far less time to compress and will thus should give you a proper frame rate when you play back the recording. Try them and let us know here how it works for you.

    Best Wishes,
    Mark