def SampleRandomFrames(model_input, num_frames, num_samples):
"""Samples a random set of frames of size num_samples.
Args:
model_input: A tensor of size batch_size x max_frames x feature_size
num_frames: A tensor of size batch_size x 1
num_samples: A scalar
Returns:
`model_input`: A tensor of size batch_size x num_samples x feature_size
"""
batch_size = tf.shape(model_input)[0]
frame_index = tf.cast(
tf.multiply(
tf.random_uniform([batch_size, num_samples]),
tf.tile(tf.cast(num_frames, tf.float32), [1, num_samples])), tf.int32)
batch_index = tf.tile(
tf.expand_dims(tf.range(batch_size), 1), [1, num_samples])
index = tf.stack([batch_index, frame_index], 2)
return tf.gather_nd(model_input, index)
## A function to sample evenly spaced frames
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