pub unsafe static AVVideoAverageNonDroppableFrameRateKey: Option<&'static NSString>AVVideoSettings only.Expand description
The desired average number of non-droppable frames to be encoded for each second of video.
Some video encoders can produce a flexible mixture of non-droppable frames and droppable frames. The difference between these types is that it is necessary for a video decoder to decode a non-droppable frame in order to successfully decode subsequent frames, whereas droppable frames are optional and can be skipped without impact on decode of subsequent frames. Having a proportion of droppable frames in a sequence has advantages for temporal scalability: at playback time more or fewer frames may be decoded depending on the play rate. This property requests that the encoder emit an overall proportion of non-droppable and droppable frames so that there are the specified number of non-droppable frames per second.
For example, to specify that the encoder should include an average of 30 non-droppable frames for each second of video:
[myVideoSettings setObject: @ 30 forKey:AVVideoAverageNonDroppableFrameRateKey];
See also Apple’s documentation