In short: the chunk media transformation tool lets you chop up a video into shorter video clips. Think of it like the editing room at a Hollywood studio: you're taking the full length of the video and cutting it into shorter, more manageable "chunks". (Note: chunking doesn't apply to images—see tile media for that.)
How does the chunk tool work?
When you chunk a video, you will specify a length (in seconds) that you want the shorter videos to be. For instance, if you're chunking a video that's 100 seconds long, and you select the new length as 10 seconds, you'll get 10 chunked videos of 10 seconds each.
Keep in mind: videos are created with different frame rates—the number of frames contained in each second (e.g. 120 frames per second, or 120 fps). Using the example above, if you've chunked your 100 second video into 10 chunks of 10 seconds each, those chunked videos will contain 1,200 frames (120 frames per second x 10 seconds).
How to chunk a video
Open the Dataset that contains the video(s) you want to chunk. Select the video(s) and click Transform, then select Chunk.
Note: if you want to chunk all videos in a Dataset uniformly, you can simply select the entire Dataset from your Datasets table and click "Transform" to apply the chunk tool.
First, specify a Dataset where you want your new chunked videos to end up. We highly recommend selecting a different Dataset.
Next, choose a clip length in seconds. Remember: if your video has a very high frame rate (in fps), even a 10 second video could still contain a lot of frames! A good rule of thumb for video annotation is to try to keep videos at or under 50 frames each, when possible.
Click Chunk, then sit back and relax—your new, chunked videos will start appearing in your target Dataset shortly!
Why and when should I chunk a video?
Technically, you can chunk any video you have in a Dataset, but that doesn't mean that you'll want to.
Like all of our media transformation tools, chunking is generally meant to help make your images easier to annotate. Since you or other users in your account will need to review the image and label the feature(s) you're looking for, you'll want to format that video to make those features as easy to find as possible.
Chunking a really long video into smaller, more manageable clips will greatly reduce the amount of frames you have to consider at once when annotating. This is because you won't have to scrub back and forth over and over again in the video timeline to make sure you've inspected the entire video. It also means multiple people can work on different segments of the same video in parallel, greatly speeding up your overall annotation time.
Believe me, this really does make a big difference!
Therefore, the chunk tool is especially useful when you have a long video that has a high frame rate. When considering whether you should chunk a video, use this simple calculation to help:
Length of original video (in seconds) x frame rate (in frames per second) = total frames
Now ask yourself: would I be able to look at
total frames and label the objects I'm looking to find all in one sitting, or would that be exhausting? If the answer is "yes, that sounds exhausting!" then you should probably chunk your video!