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Tracking markers and video clip goes out of sync.
Closed, ArchivedPublic


--- Operating System, Graphics card ---
Windows XP 32bit sp3
Nvidia GeForce GT 240

--- Blender version with error, and version that worked ---
error with 2.63 and 2.67RC1

--- Short description of error ---
The blender test footage video clip fabric-eingang.avi found here:

doesn't track properly for me. It can look OK during the tracking phase but when it is played back it goes out of sync after a while. Like it's a couple of frames behind the video. It can happen at a different frame number from time to time. What seems to be happening is that the marker suddenly goes back to exactly the previous frame's spot and then forward again, like it was loading the wrong frame suddenly during tracking. You can usually see a spike in the graph view where it happens. If I track one frame at a time or choose any other speed than fastest in the tracking settings, the error seems to happen closer to the beginning.

I have seen similar things happen on another video file before but it doesn't happen an all. Image-sequences always worked fine for me.

The computer only has 2GB of memory and "memory cache limit" is set to 1024 in preferences.
If I choose less frames to track and press Alt+A before tracking so that it gets cached, it seems to track that bit properly.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
Open Blender
Choose motion tracking layout
Open fabric-eingang.avi
Ctrl click to place a marker on a good spot. (White spot on column for example)
Press Ctrl+T to track marker
Press Alt+A to play and observe how the marker and image goes "out of sync"



Event Timeline

This is not tracking-related, this is ffmpeg thing. Something to do with the seek code. Will try to figure issue out.

Re-assigning to Peter, he knows FFmpeg stuff much better than me.

Peter, this is likely something to do with seek code, and timecodes doesn't seem to help here. Here's steps to reproduce seeking error:

- Open in sequencer, make it so strip starts at frame 1.
- Set current frame 200
- Save file, and re-open it so all the caches and buffers are reset
- Jump to first frame

It'll give seek failure message when running blender --debug-ffmpeg, and the frame displayed on the screen wouldn't be correct as well.

Tested different itmecodes and it didn't help.

Sergey Sharybin (sergey) closed this task as Archived.May 29 2014, 10:57 AM

Archiving for now. Better dealing with video sync is in our TODO anyway, and it's not usually up to blender actually. FFmpeg have it's own issues and it might simply not work for some videos..