Magic-number/taxonomy pass: central wire-format + sector + unit consts

- libfreemkv::consts: coding_type::* (ES coding-type bytes), pes_stream_id::*
  + PAYLOAD_RANGE, SECTOR_BYTES (usize) + SECTOR_BYTES_U64 (offset math)
- replace bare wire-code/sector literals across disc, mpls, clpi, labels,
  m2ts_mux, ps, tsmux, file_sector_source, extract
- remove two unreachable secondary-stream match arms in mpls parse_stream_entry

src/consts.rs

@@ -8,8 +8,18 @@
 
 /// Bytes per logical sector on every optical medium freemkv reads
 /// (Blu-ray, DVD-Video, CD-ROM Mode 1). Universal — hence unprefixed.
+///
+/// `usize` because its dominant use is buffer sizing and slice indexing, where
+/// Rust *requires* `usize` (`vec![0u8; SECTOR_BYTES]`, `buf.len() < SECTOR_BYTES`).
+/// For byte-offset / capacity arithmetic — which is `u64` because a disc can
+/// exceed 4 GiB — use [`SECTOR_BYTES_U64`] instead of casting at each site.
 pub const SECTOR_BYTES: usize = 2048;
 
+/// [`SECTOR_BYTES`] as `u64`, for byte-offset and capacity arithmetic. The
+/// single `usize → u64` boundary cast lives here, once, so offset math across
+/// the workspace reads as `sectors * SECTOR_BYTES_U64` with no per-site cast.
+pub const SECTOR_BYTES_U64: u64 = SECTOR_BYTES as u64;
+
 /// Bytes per MPEG-2 transport-stream packet. Common to all MPEG-TS, not just
 /// Blu-ray — prefixed by the format, not a disc type.
 pub const TS_PACKET_BYTES: usize = 188;
@@ -31,3 +41,80 @@ pub const TS_PAYLOAD_BYTES: usize = TS_PACKET_BYTES - TS_HEADER_BYTES;
 /// prefixed with the [`BD_TIMESTAMP_PREFIX_BYTES`] arrival-timestamp header.
 /// A BDAV/M2TS construct only — DVD VOBs have no source packets — hence `BD_`.
 pub const BD_SOURCE_PACKET_BYTES: usize = TS_PACKET_BYTES + BD_TIMESTAMP_PREFIX_BYTES;
+
+/// Elementary-stream coding-type codes — the single source of truth for the
+/// byte that identifies a stream's codec.
+///
+/// This is one registry used in two places that share the same value space:
+/// the MPEG-TS PMT `stream_type` (ISO/IEC 13818-1 Table 2-34) and the Blu-ray
+/// STN/CLPI `stream_coding_type` (BD-ROM Part 3). The standardized video codes
+/// (`0x02`, `0x1B`, `0x24`, `0xEA`) are ISO assignments; the `0x80..=0xA2`
+/// audio/graphics codes sit in the ISO user-private range and follow the
+/// Blu-ray Disc Association / ATSC A/52 convention. Because every consumer
+/// reads or writes this single byte, the family is unprefixed — the scope is
+/// "any elementary stream freemkv parses or muxes".
+///
+/// Each constant is `u8`: the spec defines an 8-bit field and the code compares
+/// it directly against a byte read from the buffer, so no casts are needed.
+pub mod coding_type {
+    /// MPEG-2 video (ISO/IEC 13818-1 Table 2-34).
+    pub const MPEG2_VIDEO: u8 = 0x02;
+    /// H.264 / AVC video (ISO/IEC 13818-1 Table 2-34).
+    pub const H264: u8 = 0x1B;
+    /// HEVC / H.265 video (ISO/IEC 13818-1 Table 2-34, 2015 amendment).
+    pub const HEVC: u8 = 0x24;
+    /// SMPTE VC-1 video (BD-ROM convention, ISO user-private range).
+    pub const VC1: u8 = 0xEA;
+
+    /// LPCM audio (BD-ROM convention).
+    pub const LPCM: u8 = 0x80;
+    /// Dolby Digital (AC-3) audio (BD-ROM / ATSC A/52 convention).
+    pub const AC3: u8 = 0x81;
+    /// DTS audio (BD-ROM convention).
+    pub const DTS: u8 = 0x82;
+    /// Dolby TrueHD audio (BD-ROM convention).
+    pub const TRUEHD: u8 = 0x83;
+    /// Dolby Digital Plus (E-AC-3 / AC-3+) audio (BD-ROM convention).
+    pub const AC3_PLUS: u8 = 0x84;
+    /// DTS-HD High Resolution audio (BD-ROM Part 3-1).
+    pub const DTS_HD_HR: u8 = 0x85;
+    /// DTS-HD Master Audio (lossless) (BD-ROM Part 3-1).
+    pub const DTS_HD_MA: u8 = 0x86;
+
+    /// Presentation Graphics — PG subtitle stream (BD-ROM HDMV).
+    pub const PG: u8 = 0x90;
+    /// Interactive Graphics — IG / BD-J menu overlay, NOT a subtitle (BD-ROM HDMV).
+    pub const IG: u8 = 0x91;
+    /// Text subtitle stream (BD-ROM HDMV).
+    pub const TEXT_SUBTITLE: u8 = 0x92;
+
+    /// Secondary Dolby Digital Plus audio (BD-ROM convention).
+    pub const AC3_PLUS_SECONDARY: u8 = 0xA1;
+    /// Secondary DTS-HD audio (lossless MA, not lossy HR) (BD-ROM convention).
+    pub const DTS_HD_SECONDARY: u8 = 0xA2;
+}
+
+/// MPEG PES `stream_id` codes — the byte after the `00 00 01` start-code prefix
+/// that identifies an elementary stream's role in a PES packet (ISO/IEC
+/// 13818-1 Table 2-22). Shared by the program-stream demuxer and the TS/M2TS
+/// muxers, so defined here once. Each is `u8` (matches the byte on the wire).
+pub mod pes_stream_id {
+    /// Video stream (`110x xxxx`; freemkv emits the base id `0xE0`).
+    pub const VIDEO: u8 = 0xE0;
+    /// private_stream_1 — AC-3 / DTS / LPCM / PGS subtitle payloads.
+    pub const PRIVATE_STREAM_1: u8 = 0xBD;
+    /// padding_stream — stuffing bytes only, no payload to demux.
+    pub const PADDING_STREAM: u8 = 0xBE;
+    /// private_stream_2 — DVD navigation (PCI/DSI); carries no muxable ES.
+    pub const PRIVATE_STREAM_2: u8 = 0xBF;
+
+    /// Highest video stream_id — the `110x xxxx` video range tops out at 0xEF.
+    pub const VIDEO_MAX: u8 = 0xEF;
+
+    /// Inclusive range of every PES `stream_id` that carries demuxable payload:
+    /// [`PRIVATE_STREAM_1`] (0xBD) through [`VIDEO_MAX`] (0xEF) — i.e. private
+    /// stream 1/2, padding, MPEG audio (0xC0-0xDF) and video (0xE0-0xEF). The
+    /// pack (0xBA), system-header (0xBB) and program-end (0xB9) codes sit below
+    /// this range and are deliberately excluded: they're structural, not ES.
+    pub const PAYLOAD_RANGE: core::ops::RangeInclusive<u8> = PRIVATE_STREAM_1..=VIDEO_MAX;
+}