whats the meaning of num frames, sampling rate and slowfast alpha?

In yaml file, i found a lot of paramaters, but i cant understand the meaning of it very well.

For example, i want to change the input frame rate, which paramaters i should to change, NUM_FRAMES?
whats meaning of NUM_FRAMES?? If have 75frame, then average choose 32 frame?

`DATA:
NUM_FRAMES: 32
SAMPLING_RATE: 3
TRAIN_JITTER_SCALES: [256, 320]
TRAIN_CROP_SIZE: 224
TEST_CROP_SIZE: 256
INPUT_CHANNEL_NUM: [3, 3]
SLOWFAST:
ALPHA: 4
BETA_INV: 8
FUSION_CONV_CHANNEL_RATIO: 2
FUSION_KERNEL_SZ: 7`