https://github.com/ammaraskar/simsreiaparser
Libraries to parse and encode .reia file for sims2
https://github.com/ammaraskar/simsreiaparser
Last synced: 10 months ago
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Libraries to parse and encode .reia file for sims2
- Host: GitHub
- URL: https://github.com/ammaraskar/simsreiaparser
- Owner: ammaraskar
- License: mit
- Created: 2022-11-27T00:53:28.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2025-02-16T15:31:47.000Z (over 1 year ago)
- Last Synced: 2025-07-30T20:36:32.921Z (11 months ago)
- Language: Python
- Homepage:
- Size: 605 KB
- Stars: 9
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# SimsReiaParser
Libraries to parse and encode .reia file for sims2
https://user-images.githubusercontent.com/773529/204124123-9a72bdbb-1de3-4cf7-a1da-d0724fc9d3bc.mp4
## Format Details
`.reia` files are how Sims2 stores the videos for its neighborhood previews in
its main menu. They seem to be a relatively custom format, this is an overview
on how it encodes video data:
### Header
`.reia` files first have a header with metadata, the fields are:
| Offsets | Type | Description (values in hex) |
|---------------|--------|---------------------------------------------------------------|
| `0x00 - 0x03` | Magic | `52 49 46 46` "RIFF" |
| `0x04 - 0x07` | uint32 | Size of the "chunk" which is the rest of the file |
| `0x08 - 0x0f` | Magic | `52 65 69 61 68 65 61 64` "Reiahead" |
| `0x10 - 0x13` | uint32 | `18` Size of the metadata to follow (always 24 in practice) |
| `0x14 - 0x17` | uint32 | `01` Unknown, always 1 |
| `0x18 - 0x1b` | uint32 | Horizontal resolution in pixels |
| `0x1c - 0x1f` | uint32 | Vertical resolution in pixels |
| `0x20 - 0x23` | uint32 | Frames per second numerator (see below) |
| `0x24 - 0x27` | uint32 | FPS denominator. FPS given by `fps_numerator/fps_denominator` |
| `0x28 - 0x2b` | uint32 | Number of frames in the file |
| `...` | frames | See below |
### Frames
After the header, there are a sequence of frames. Each frame is
| Offsets | Type | Description (values in hex) |
|---------------|------------|----------------------------------|
| `0x00 - 0x03` | Magic | `66 72 6d 65` "frme" |
| `0x04 - 0x07` | uint32 | Size of the frame data to follow |
| `...` | Frame Data | See below |
Note that the frame data is padded to be 2-byte aligned. So if the frame size
was `3`, there will be `4` bytes of data **instead of 3** before the next
`frme` magic bytes.
### Frame Data - Run Length Encoding
The format uses some interesting tricks for compression: run-length encoding,
encoding differences in pixel values between frames and reusing blocks of pixels
that stay the same.
Each pixel has a standard 24-bit color depth storing 8-bits for the RGB channels
in little endian.
Images are stored in blocks of `32x32` pixels. So a reia file with a resolution
of `128x128` is constructed of `4x4 = 16` blocks. Each block is parsed as
follows:
* A single byte is read. `0` indicates this `32x32` block should be reused from
the previous frame. Any other value means the block data is to follow.
* A byte is read and treated as a signed 8-bit integer `n`:
- If the value is negative, then a single pixel value should be read and
repeated `(-n) + 1` times.
- If the value is positive, then `n + 1` unique pixel values should be read.
* The pixel values retrieved are *relative* to the previous frame unless it is
the first frame of the file. So a change from a red value of `200` to `205` is
encoded as `5`. A change from `255` to `0` is encoded as `1`.
In order to get the actual pixel value you must use `(previous + current) & 0xFF`.