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ExtractFrames

Retrieve frames (as separate images) from a referenced video.

Frames are returned as encoded images in the array of blobs.

Parameters​

  • video_ref: Reference to videos within the transaction (either the result of a FindVideo or an AddVideo) from which the corresponding frames will be retrieved.

  • frame_spec: specification of what frames numbers to extract.

  • [optional] as_format: Specify the format of the returned frames.

  • [optional] operations

Details​

The frames to be extracted and returned can be specified in two ways: either by specifying the frame_spec parameter with an array of frame indexes, or by passing an object (see examples below) with start, stop, and step indexes.

Examples​

Find the video with the "name" property equal to "my_video_1", and returns 1st, 10th, and 100th frames of it:


    [{
        "FindVideo": {
            "_ref": 1,
            "constraints": {
                "name": ["==", "my_video_1"]
            }
        }
    }, {
        "ExtractFrames": {
            "video_ref": 1,
            "frame_spec": [0, 9, 99]
        }
    }]

Successful response:


    [{
        "FindVideo": {
            "status": 0,
            "returned": 0
        }
    }, {
        "ExtractFrames": {
            "status": 0,
            "returned": 3,
            "blobs_start": 0
        }
    }]

Find the video with the "name" property equal to "my_video_1", and return 1 every 5 frames in the range between the 1st and the 100th frame with 1080p resolution as "PNG":


    [{
        "FindVideo": {
            "_ref": 1,
            "constraints": {
                "name": ["==", "Family Guy"]
            },
            "unique": true
        }
    }, {
        "ExtractFrames": {
            "video_ref": 1,
            "as_format": "png",
            "frame_spec": {
                "start": 0,
                "stop": 99,
                "step": 5
            },
            "operations": [{
                "type": "resize",
                "width": 1920,
                "height": 1080
            }]
        }
    }]

Successful response:


    [{
        "FindVideo": {
            "status": 0,
            "returned": 0
        }
    }, {
        "ExtractFrames": {
            "status": 0,
            "returned": 20,
            "blobs_start": 0
        }
    }]