Difference of frame size and cv::Mat size [closed]

asked 2014-05-23 11:20:05 -0500

Tariq gravatar image

updated 2014-05-24 01:25:33 -0500

berak gravatar image

Dear all,

I am extracting frames from a video stream of approximately 2 minutes at 25fps. Total size of the video is 4.4MB. I calculate size of individual frame as follows:

I convert the file size into KBytes(4.41024) and calculate size of individual frame in KBytes. (4.41024) / (120*25) = 1.5 KBytes (size of one frame)

In OpenCV, I get the following frame data: Rows: 288 Cols: 352 Channels: 3 Size: [352 x 288] step: 1056 (# of bytes occupied by each row)

If I calculate size of one frame in Bytes: 1056*288 =304128 Bytes = 297KB

Could you please comments on this size calculation and explain the difference of size?

Regards,

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Closed for the following reason the question is answered, right answer was accepted by sturkmen
close date 2020-10-06 07:56:45.101764

Comments

1

Maybe the video is compressed?

isarandi gravatar imageisarandi ( 2014-05-23 11:51:00 -0500 )edit

you can't guess anything about the frame-size from the on-disk size of a video.

apart from the ompression, there might be additional audio tracks or subtitles in japanese.

berak gravatar imageberak ( 2014-05-24 01:24:21 -0500 )edit

@isarandi, Video is recorded as MP4.

@berak, Video is recorded as MP4 and there are no audio/subtitles in the video.

Tariq gravatar imageTariq ( 2014-05-31 07:40:55 -0500 )edit