Audio and video not synced
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Audio and video not synced
I see several people have had problems syncing audio and video but I haven't really seen a solution.
I am running ELAN 4.0.1 on Windows 7. The computer is brand new and hardware specs would not be an issue.
The video and audio files are identical in length; I have checked with other programs.
If I make the audio file the master, then the waveform viewer works, i.e. it matches the audio. However the video is about half a second behind.
If I make the video file the master, then the audio and video seem to be synced (although I don't know whether I'm hearing sound from the video or audio file, haven't checked that). But in any case, the waveform viewer now has problems. If I put the cursor in a given place and play, it seems to work. But if I select a chunk of speech and play, it starts correctly at the beginning of it, but plays about half a second too long at the end.
I have tried numerous different video encodings and nothing seems to fix this. I would be grateful for a fix. Thanks a lot.
Re: Audio and video not synced
PS. I tried this on version 3.9 and 3.4 too, the bug is the same.
Here is a concrete example that makes it clear this is a bug, not an issue with my files.
Speech sample:
"I'm going to ask you to do some ... talking"
If I select in the waveform viewer "I'm going to ask you to do some", then hit "Play selection", it plays:
"I'm going to ask you to do some ... talk-"
In other words, it plays too long.
But if I put my cursor at the end of this very same selection, then it play, it plays:
"... talking".
which is correct.
So the fundamental bug seems to be that when you play a selection, it plays too long at the end. This is a problem for accurate annotation of timing info.
Re: Re: Audio and video not synced
First of all (to clear this up), if the video is the master, the sound you hear comes from the audio track of the video file. The wav file in such case is only used for visualization by the waveform viewer. You only hear the sound from the wav file if it is the master.
The two described situations in the first part of your message (1. audio master: waveform ok, video is behind, 2. video master: sound is in sync with video, waveform incorrect) could still indicate that the audio and video files are out of sync. But probably something else is going on; what you describe in the second part of your message cannot be explained by the files being out of sync.
If I understand it correctly you can play a selection and when playing selection has ended and you click the play button you hear the last part of what has been played as the selection again. (In your example you hear "talk" twice.)
So far I haven't been able to reproduce this on any of the pc's available to me (including a Windows 7 laptop). In your case, does this "doubling" effect also occur when the audio file is the master?
It is obvious that this is a serious problem for accurate annotation, but it is difficult to fix such problem without being able to reproduce the problem.
-Han
Release of ELAN 4.3.0
