How to speed up identify on images with multiple frames?

[0xJohny]

When I run identify on animated GIF, or MP4 video, the execution time can go up to minutes, as it is identifying every single frame.

The command I want to run is:

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identify -format "%Q %m %n %w %h" image.gif

• %Q - compression quality
• %m - image format
• %n - number of frames
• %w - width
• %h - height

I know that I can speed it up by specifying only one frame in path (image.gif[0]), but that would mean that %n would always return 1, and I need that value. ImageMagick is really inefficient in this. For example, even simple 'identify -format "%n" image.gif' is doing the identification process on every single frame, as opposed to just returning the requested total number of frames.

[snibgo]

Does "-ping" help?

[0xJohny]

Doesn't seem to. Tried:

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identify -format "%n" -ping test.mp4

And it was as long as before (over a minute). Also tried other simple formats like %w, and same result. (I'm using ImageMagick 6.8.6-7 Q8)

How is -ping supposed to work? The documentation doesn't say much...

[snibgo]

As I understand it, "-ping" tells IM to read the metadata, but not to read and decode the actual image data. I always put it as the first argument:

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identify -ping -format "%n" test.mp4

[snibgo]

For basic metadata of MP4 and other video, I use ffmprobe.

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D:\pictures\20130713>%FFM%ffprobe -show_streams d:\pictures\20130523\gopr0006.mp4
:
width=1920
height=1080
:
r_frame_rate=30000/1001
:
duration=1133.565767
:

The number of frames is the duration (seconds) multiplied by the frame rate (frames per second).

1133.565767 * 30000/1001 = 33973.00000999001 frames.

exiftool also works on MP4 files, but seems to give less precision.

exiftool works well for GIF files, giving an exact frame count.