What is objective=pred_x0 and how do you use it?

[sgbaird]

        if self.objective == 'pred_noise':
            target = noise
        elif self.objective == 'pred_x0':
            target = x_start
        else:
            raise ValueError(f'unknown objective {self.objective}')

[dome272]

With this option you can predict x_0 directly from x_t. However, this was shown in the papers to not work well. See https://arxiv.org/pdf/1503.03585.pdf on page 2.