Produce a thumbnail from an AVI for MPG?

Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
Post Reply
NeilF

Produce a thumbnail from an AVI for MPG?

Post by NeilF »

Is it possible to (quickly) produce a thumbnail image from an AVI or MPG file?
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Re: Produce a thumbnail from an AVI for MPG?

Post by anthony »

Generally the programs that generate the thumbnail use a specialized video program to grab a frame 1 minute into the animation or 1/3 through the animation (I prefer the latter). Once they have a frame they thumbnail and then add 'film strips and holes' along the edges.
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
NeilF

Re: Produce a thumbnail from an AVI for MPG?

Post by NeilF »

anthony wrote:Generally the programs that generate the thumbnail use a specialized video program to grab a frame 1 minute into the animation or 1/3 through the animation (I prefer the latter). Once they have a frame they thumbnail and then add 'film strips and holes' along the edges.
So imagemagick can't do anything like this? ie: Grab even just the first frame from a video?
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Re: Produce a thumbnail from an AVI for MPG?

Post by anthony »

It can, but does so by calling another 'delegate' program to decode the video.

Imagemagick is often used by video processing programs, but for processing individual images, not for actual video processing in.

For some information on video handling with IM see.. IM examples, Common Image file formats
MPEG, M2V and AVI
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
User avatar
fmw42
Posts: 25562
Joined: 2007-07-02T17:14:51-07:00
Authentication code: 1152
Location: Sunnyvale, California, USA

Re: Produce a thumbnail from an AVI for MPG?

Post by fmw42 »

Anthony, I think the issue is one of speed! The question I think really is, will IM with the appropriate delegate have to open/read all the frames from the video, just to get to and convert even the first frame or will it have random access to any frame without opening/reading all the other frames of the video.
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Re: Produce a thumbnail from an AVI for MPG?

Post by anthony »

As it is using a delegate it will problem do that, but I can be certain without looking into it further

In any case for video IM is probably not the right tool. For processing the frame once you have it IM is the right tool!
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
NeilF

Re: Produce a thumbnail from an AVI for MPG?

Post by NeilF »

anthony wrote:It can, but does so by calling another 'delegate' program to decode the video.

Imagemagick is often used by video processing programs, but for processing individual images, not for actual video processing in.

For some information on video handling with IM see.. IM examples, Common Image file formats
MPEG, M2V and AVI
Thanks for that! So the link you gave, seems to suggest not to use image magic to grab a thumbnail for a video? Instead you'd use (for example) "mplayer" or "mencode" to grab a thumbnail (from somewhere near the start of the video) which you'd then pick up and further manipulate (if necessary) with ImageMagick?

From your example, I'd issue a command something like this to grab a single frame 5 seconds into a video:-

mplayer file.avi -vf scale=320x240 -ss 00:05 -ao null -vo png:z=3 -frames 1
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Re: Produce a thumbnail from an AVI for MPG?

Post by anthony »

That is the recommendation.


however 5 seconds in a typical video is usually blank, or highly variable title area.

I recommend getting a thumbnail 1/3 of the way through any video to get a thumbnail that has a better chance of getting something reasonable to use a thumbnail.
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
Post Reply