torchaudio was defaulting to the torchcodec backend which requires FFmpeg
shared libraries not present in the ComfyUI venv, silently skipping every
clip and producing an empty dataset.
Also add experiments/vocoder_finetune.json for the BJ vocoder LoRA run
(lr=3e-4, rank=128, 10k steps).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
