    def input_transformed_channels(self):
        """The number of channels in the audio after feature transforms"""
        # TODO: move this into individual transforms
        # TODO: deprecate transforms
        _cur = self.config.get("transforms", {})
        ft_transforms = self.config.get("feature_transforms", {})
        if _cur and ft_transforms:
            _cur.update(ft_transforms)
        else:
            _cur = self.config.get("feature_transforms", {})
        cur = _cur.get("_train", [])

        _channels = self.input_channels
        if "delta_deltas" in cur:
            _channels *= 3

        return _channels
The number of channels in the audio after feature transforms
fairseq/data/audio/data_cfg.py