Random start index in WeightDataset

[v-nhandt21]

At this line: https://github.com/xcmyz/FastVocoder/blob/a9af370be896b1096e746ce6489fb16fef8ca585/data/dataset.py#L97

If the input mel size smaller than fix-length, the random raise issue, I have try except to pass these short audios, but I just wonder it is handle in collate.

More than that, the segment size as I found in hifigan is 32, but in basic-melgan it (fix-length) is set to 140. Are there any difference between the 140 for biaobei and the one for LJspeech