Generate thumbnail PNG and GIF for each video

[evamaxfield]

Use Case

Please provide a use case to help us understand your request in context

Using our card example on the frontend documentation: https://councildataproject.org/cdp-frontend/?path=/story/library-cards-events--meeting-search-result

We need a thumbnail for each event. And we planned for this in two ways, our event schema in our database has both a static and hover thumbnail. https://councildataproject.org/cdp-backend/cdp_backend.database.html#cdp_backend.database.models.Event

Solution

Please describe your ideal solution

• Write a function for the static thumbnail generation. Takes in a video file path, grabs a frame from the 30 second mark, saves to PNG, returns the save path.
• Write a function for the hover thumbnail generation. Takes in a video file path, grabs 10 frames from every 1/10th of the video file. So if the video is 1 hour long, it would grab a frame from every 6 minutes. Saves those frames to a GIF and returns the save path.

imageio is really all that is needed here.

Alternatives

Please describe any alternatives you've considered, even if you've dismissed them

This can become much more complicated later. But for right now we really just need to get work done. The 30 second and the every 1/10th of the video file are chosen some what randomly but they should be okay. Down the line we may want have some better frame selection in place but not now.

After these two functions are written, we will need to add them to the pipeline. I am envisioning that a single prefect task would do the following:

def generate_thumbnails(video_uri: str) -> Tuple[str, str]:
    # Download video
    local_video_copy_path = external_resource_copy(video_uri)

   # Process to get thumbnails
    static_thumbnail_path = get_static_thumbnail(local_video_copy_path)
    hover_thumbnail_path = get_hover_thumbnail(local_video_copy_path)

   # Store files in storage
    static_thumbnail_uri = upload_file(static_thumbnail_path)
    hover_thumbnail_uri = upload_file(hover_thumbnail_path)
    
    # Store file URIs in DB
    static_thumbnail_ref = upload_file_db(static_thumbnail_uri)
    hover_thumbnail_ref = upload_file_db(hover_thumbnail_uri)

    return static_thumbnail_ref, hover_thumbnail_ref