PURE DATA forum~
...that deal with pure data
You are not logged in.
#1 2010-02-10 17:53:44
- SlicelikeaninJa
- Member
Jumping to frame - avi
Hi there... another newb question!
I've got a patch going where I can store cue points in an array. These cue points simply refer to frame numbers and right now are just going straight into the right input of pix_film.
Now I'm jumping between 3 points (say 10, 60, and 100) while the video (avi) is being rendered, but not playing... so it's just displaing still frames.
The weird thing is that the frame that appears when I hit the button for frame #60 changes depending on whether I jump to it from frame #10, or frame #100!
So depending on what pix_film received last, frame #60 could display one of two different things!
I'm missing something right??
cheers
J
Offline
#2 2010-02-10 21:53:04
- nestor
- Member
Re: Jumping to frame - avi
Hard to say, I think AVI can contain one of several codecs. With video that is time-compressed, you can't just jump to any frame: The video is made up of P-frames and I-frames, the I's are what you would think of as a frame; a picture representing what you see on the screen while the video is playing. P-frames represent the difference between frame n(i-frame) and frame n+1(p-frame). So, if you try and go to a P-frame with most video players, they will jump to the closest Iframe and resume playback from there. REALLY bad explanation, right?
Offline
#3 2010-02-11 12:11:57
- SlicelikeaninJa
- Member
Re: Jumping to frame - avi
Actully a fairly good explanation!
It would be nice if PD could extrapolate and display the n-1 and n+1 frames... but alas.
Offline
#4 2010-02-11 17:24:17
- LarsXI
- Member
Re: Jumping to frame - avi
One response to this issue is to convert your video clips that do not have interframe compression. Or make new clips and designate all frames as key-frames in the codec settings. I'm not sure how comparability is with various codecs like lagarith and DV, but making all frames key-frames should allow for good compatibility.
edit -
note that file sizes will be much larger
Last edited by LarsXI (2010-02-11 17:24:43)
we, the undersigned
Offline
#5 2010-02-11 21:00:32
- nestor
- Member
Re: Jumping to frame - avi
Yes, either convert to all I-Frames, or use a codec that is not temporally compressed. In FFMPEG, you can set use the -intra flag to encode only I-Frames. So; ffmpeg -i yourmovie.avi yournewmovie.avi SHOULD work, but IDK.... Otherwise, convert the movie to motion-jpeg or something.
Offline