# Supported formats

> The five Hap variants this package decodes, and the two it detects but rejects.

Hap is a family of variants rather than a single codec. Each stores frames in a block-compressed texture format the GPU reads directly.

| Variant     | Compression        | Alpha |
| ----------- | ------------------ | ----- |
| Hap         | DXT1               | —     |
| Hap Alpha   | DXT5               | yes   |
| Hap Q       | YCoCg DXT5         | —     |
| Hap Q Alpha | YCoCg DXT5 + RGTC1 | yes   |
| Hap R       | BC7                | —     |

Hap Q Alpha decodes as real transparency rather than an approximation: the player uploads two textures per frame — a YCoCg colour plane and an RGTC1 alpha plane — and combines them in a decode shader.

## Variants that will not decode

HapA (alpha-only) and Hap HDR (BC6H) are recognised in the container but not decoded. Opening one fails at `OpenAsync`/`Open` with `HapOpenStatus.UnsupportedFormat` rather than producing a broken frame — see [open results](/hap/hap-player/#open-results) for the full status list.

## Chunked frames

Hap frames may be split into chunks so that decompression can be parallelised. The number of threads used to decompress one frame’s chunks is a process-wide setting, `HapPlayer.DecodeThreadCount`; see [process-wide tuning](/hap/performance/#process-wide-tuning).

## Encoding source material

This package only reads Hap; it does not encode. Encode with whatever tool your pipeline already uses — the variant choice is the meaningful decision:

- **Hap** is the cheapest per frame and the largest visual compromise.
- **Hap Q** is the usual default when quality matters; it roughly doubles the per-frame byte size of Hap, which is also the thing that dominates playback cost.
- **Hap R** (BC7) is the highest quality of the three opaque variants.
- Reach for the **Alpha** variants only when you actually need transparency — Hap Q Alpha costs two texture uploads per frame instead of one.

Per-frame byte size is what drives main-thread cost, so it is worth treating the variant and the resolution as one combined budget decision. See [playing many videos at once](/hap/performance/).