Thumbnail is a small image representing particular resource. The resource should be something what is visible - image, video, document, text. Music are not a visual files - they have only sounds so it is not possible to create a thumbnail from it. To represent music file You have to use Media Art attached to this file. See next FAQ What media arts are?
In other words: thumbnail is a small, static version of the resource.
Media Art is some image which is attached/distributed with the file. It could be an album cover, movie poster, cd cover etc. It is not a thumbnail - media art are only related to the file, but they are not created based on the file itself.
In this dcumentation when we are saying media art we mean an object which is describing some media art. The image itself we will be calling as a 'media art's content'. You can have an media art object but it does not mean that corellated image file exists. You can check it easily or even You can try to request that image from some 3rd parties service. Unfortunatelly currently there is no such a service on the platform.
As a media art's content we mean an image itself.
Let's imagine that we have a video file with some movie. A thumbnail is a one frame taken from that movie, resized to some standard thumbnails size. So it is created based on that file. Media art on the other hand is something what is attached to that file - it could be a second file poster.jpeg which contains poster of that movie. So media art content is not created based on file - it is just an image connected with that file.
If You will get that video file itself, without anything else, You would be able to recreate only thumbnail. Media art cannot be created again from just a file - some additional services are needed.
Flavors are connected with thumbnails. They are lots of thumbnail's type and every type can have a different size. Flavor is a name for thumbnail's type. You can have flavor like 'very-small' which will describe thumbnails with 50x50 resolution, flavor 'very-big' for thumbnails with 250x250 resolution, flavor 'half-screen' with 400x240 resolution and so on. When You are asking for thumbnails You need to specify what type of thumbnails You need. By default 'normal' flavor is used. You can check what flavors Thumbnailer support by calling function from Thumbnails::Thumbnailer::getFlavors(). If You want to know the size of particular flavor You can use Thumbnails::Thumbnailer::getFlavorSize(QString flavor).
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