Compression issue

classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

Compression issue

TomTrainer
Hi,

Ive been analysing videos for the speed of the subjects being recorded. When
i open the video in imageJ, the animation seems to be much faster than the
actual file video. ImageJ seems to know the real fps but the last frame is
much smaller than the actual one, making the video very fast. Why is this
compression of video length happening?

Many thanks



--
Sent from: http://imagej.1557.x6.nabble.com/

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html
Reply | Threaded
Open this post in threaded view
|

Re: Compression issue

Michael Schmid-3
Hi Tom,

sorry, I have not seen this problem. I guess you refer to AVI files
opened by ImageJ? Or do you talk about QuickTime?
Do you have a short sample video that you can post somewhere, together
with the information what the frame rate should be?

If it is an AVI, what would also help to diagnose the problem:
Turn on debug mode (in Edit>Options>Misc), open the avi file and look at
the Log window. You should find something like this near the top of the
long list of information read from the AVI:

AVI HEADER (avih): (t=3 ms)
    dwMicroSecPerFrame=33333

[The "(t=3 ms)" is only information about the performance of the
AVI_Reader; the relevant value is dwMicroSecPerFrame]

What value do you get for dwMicroSecPerFrame, and which speed value do
you get in Image>Stacks>Animation>Animation Options?


Michael
________________________________________________________________
On 15.11.19 14:56, TomTrainer wrote:
> Hi,
>
> Ive been analysing videos for the speed of the subjects being recorded. When
> i open the video in imageJ, the animation seems to be much faster than the
> actual file video. ImageJ seems to know the real fps but the last frame is
> much smaller than the actual one, making the video very fast. Why is this
> compression of video length happening?
>
> Many thanks

--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html