The original CLAP. CNN14 audio tower + BERT text tower projected into a 1024-dim shared space, trained with symmetric InfoNCE on ~128K curated (audio, caption) pairs from FSD50K, ClothoV2, AudioCaps, MACS. Establishes that the CLIP recipe transplants cleanly to audio — and that even at modest scale, you get zero-shot classification across 16 downstream datasets.
The scaled-up successor to MS-CLAP. Swaps CNN14 + BERT for HTSAT + RoBERTa, the shared space drops to 512-dim, and the training set grows ~20x via Keyword-to-Caption augmentation (T5 turns AudioSet labels into synthetic captions) plus LAION-Audio-630K. Attention Feature Fusion handles variable-length clips. This is the CLAP that downstream systems (AudioLDM, Stable Audio, SAM Audio) actually use.
What CLAP gets via captions, MERT gets from the audio alone. A HuBERT-style transformer masks ~50% of frames and reconstructs from two simultaneous teachers: EnCodec RVQ codes (timbre, texture) and the Constant-Q Transform (pitch, harmony). The dual-teacher design is the load-bearing move — either signal alone leaves the resulting representation blind to half of what music actually is.