1. A computer system to generate music, the computer system comprising: a machine-learned neural synthesizer model comprising an autoencoder model, the autoencoder model comprising an encoder neural network and a decoder neural network; wherein the encoder neural network is configured to receive an input audio waveform and, in response, provide an embedding descriptive of the input audio waveform; and wherein the decoder neural network is configured to receive the embedding and at least a portion of the input audio waveform and, in response, predict a next sequential audio sample for the input audio waveform; one or more processors; and one or more non-transitory computer readable media that collectively store instructions that, when executed by the one or more processors cause the computer system to perform operations, the operations comprising: evaluating a loss function that compares the next sequential audio sample predicted by the decoder neural network to a ground-truth audio sample associated with the input audio waveform; and adjusting one or more parameters of the autoencoder model to improve the loss function.