After these adjustments, the synchronicity between sound and video image was fine. For example between 1:05 and 1:07 we have 200 ms delay. The correction value which is used as offset is always the difference between the offset at the end of the section and the offset at the beginning. I've corrected each section of the graph between two points separately in Wavelab. Time corrections of the audio track then were performed in Wavelab. So I conclude that the dropped frames result from disturbances in VHS cassette tape flow, and were not caused by excessive computer load when digitizing. In the audio track there were some small clicks and crackle noises too. ![]() So there were dropped frames or (in this case) delayed frames. In that range I could see stepwise movements in the digitized video. That is almost one second.įrom the 50th minute the audio delay suddenly increases sharply. ![]() At 50 minutes, the offset has been increased to 800 ms. We will notice a shift of greater 100 ms. But that's enough, so that from about the 10th Minutes you will note that the audio track lags behind the picture. Until the 50th minute there is a steadily increasing offset, which arises solely because the tape is not exactly running at 25 frames per second. In the figgure you can see the real audio delay of a fairy tale I had digitized from VHS. Of the audio delay as shown on this page.Īudio delay vs running time of a grapped VHS video (frame rate not 25 fps and dropped frames starting from 0:50) In this case, the pitch ofįluctuations with a special software like Celemony Capstan.
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