Can't get video's number of frames before processing?

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Liran
Liran 2014-7-28
评论： Walter Roberson 2016-4-21
I used videoReader--> read but i get "[]" in the number of frames field. i have tried using vision.VideoFileReader but it gives a less informative header ( without that kind of information)
I need the frame number BEFORE processing , not after. I am uploading the video so you could try yourselves

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采纳的回答

Dinesh Iyer
Dinesh Iyer 2014-7-29
Hi Lirian,
The vision.VideoFileReader system object allows reading only one frame at a time and does not allow random access.
I tried to open this file using Windows Media Player but was unable to do so. I believe I need some additional codecs as you mentioned.
Can you try to force VideoReader to read the last frame as below
if true
vidObj = VideoReader('swipeCut.mp4');
read(vidObj, Inf);
vidObj.NumberOfFrames
end
This should display the last frame read. However, this operation might take time depending upon the size of the video.
I am curious however as to why you need the total number of frames?
Hope this helps.
Dinesh
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PRUDHVI RAJU
PRUDHVI RAJU 2016-4-21
编辑：Walter Roberson 2016-4-21
%
% Read Video
video = VideoReader('fp.avi');
%video = VideoReader('sv.mp4');
%no.of frames
nframes=video.NumberOfFrames;
Walter Roberson
Walter Roberson 2016-4-21
"Note: NumberOfFrames will be removed in a future release."

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更多回答（1 个）

Dima Lisin
Dima Lisin 2014-7-28
Thre maybe something wrong with the header of your video file. Can you try VideoReader on a different file?
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Liran
Liran 2014-7-28
编辑：Liran 2014-7-28
i have used VideoReader on other videos and it was fine of course , but i really need to do it on this video (i attached it).
The video was recorded via "Rec." app on a Samsung Note 3 with android 4.4 (Kitkat) and this app records these videos the same way.
i don't know if it helps you figure out the problem but before i downloaded new codecs i couldn't even read the file at all.

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