Utils Module (src/utils.rs)

This module defines the core data structures and constants shared between the Encoder and Decoder.

Constants

• MAGIC_NUMBER: 0x4554_524E_4C53_5452 ("ETRNLSTR") identifies the file format.
• HEADER_SIZE: 1024 bytes. We reserve a fixed size for the header to make reading it predictable.
• VIDEO_WIDTH / HEIGHT: 1920x1080. We stick to 1080p to maximize compatibility with video players and hosting sites.

The FileHeader Struct

Every video file starts with this metadata structure, serialized as JSON.

pub struct FileHeader {
    pub magic: u64,           // Verification
    pub version: u32,         // Format version (v1)
    pub original_filename: String,
    pub file_size: u64,       // Bytes
    pub block_size: u32,      // Pixel block size used
    pub sha256_hash: String,  // For integrity check
    pub data_shards: usize,   // RS config
    pub parity_shards: usize, // RS config
}

Why JSON?

We use JSON (via serde) for flexibility. If we want to add fields later (e.g., encryption salt), we can do so without breaking basic parsing.