MattJackson
ff6004a567
Stream trait: read() returns PesFrame, write() accepts PesFrame. A stream is a stream — you read from it or write to it. No separate Input/Output traits. API: libfreemkv::input(url) and libfreemkv::output(url, title, codecs) Returns Box<dyn Stream>.
280 lines
8.7 KiB
Rust
280 lines
8.7 KiB
Rust
//! M2TS metadata header — embeds title/stream info in raw m2ts files.
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//!
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//! Format: [8B magic] [4B json_len] [JSON] [padding to 192B boundary] [BD-TS data...]
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//! Other tools skip the header during TS sync recovery (scan for 0x47).
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use crate::disc::{AudioStream, ColorSpace, DiscTitle, Stream, SubtitleStream, VideoStream};
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use serde::{Deserialize, Serialize};
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use std::io::{self, Read, Seek, SeekFrom, Write};
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/// Magic bytes: "FMKV" + version 1 + 2 reserved bytes.
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const MAGIC: [u8; 8] = [b'F', b'M', b'K', b'V', 0x00, 0x01, 0x00, 0x00];
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/// BD-TS packet size (header must be padded to this boundary).
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const PACKET_SIZE: usize = 192;
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/// Metadata embedded in an m2ts file.
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#[derive(Debug, Clone, Serialize, Deserialize)]
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pub struct M2tsMeta {
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/// Format version.
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pub v: u8,
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/// Title name (e.g. filename stem or disc title).
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#[serde(default)]
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pub title: String,
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/// Duration in seconds.
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#[serde(default)]
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pub duration: f64,
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/// Stream descriptors.
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pub streams: Vec<MetaStream>,
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}
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/// A single stream descriptor in the metadata.
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#[derive(Debug, Clone, Serialize, Deserialize)]
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#[serde(tag = "type")]
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pub enum MetaStream {
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#[serde(rename = "video")]
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Video {
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pid: u16,
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codec: String,
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#[serde(default)]
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resolution: String,
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#[serde(default)]
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frame_rate: String,
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#[serde(default)]
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hdr: String,
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#[serde(default)]
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label: String,
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#[serde(default)]
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secondary: bool,
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},
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#[serde(rename = "audio")]
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Audio {
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pid: u16,
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codec: String,
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#[serde(default)]
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channels: String,
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#[serde(default)]
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language: String,
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#[serde(default)]
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sample_rate: String,
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#[serde(default)]
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label: String,
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#[serde(default)]
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secondary: bool,
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},
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#[serde(rename = "subtitle")]
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Subtitle {
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pid: u16,
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codec: String,
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#[serde(default)]
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language: String,
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#[serde(default)]
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forced: bool,
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},
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}
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impl M2tsMeta {
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/// Build metadata from a disc Title.
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pub fn from_title(title: &DiscTitle) -> Self {
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let streams = title
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.streams
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.iter()
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.map(|s| match s {
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Stream::Video(v) => MetaStream::Video {
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pid: v.pid,
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codec: v.codec.id().into(),
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resolution: v.resolution.to_string(),
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frame_rate: v.frame_rate.to_string(),
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hdr: v.hdr.id().into(),
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label: v.label.clone(),
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secondary: v.secondary,
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},
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Stream::Audio(a) => MetaStream::Audio {
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pid: a.pid,
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codec: a.codec.id().into(),
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channels: a.channels.to_string(),
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language: a.language.clone(),
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sample_rate: a.sample_rate.to_string(),
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label: a.label.clone(),
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secondary: a.secondary,
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},
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Stream::Subtitle(s) => MetaStream::Subtitle {
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pid: s.pid,
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codec: s.codec.id().into(),
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language: s.language.clone(),
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forced: s.forced,
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},
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})
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.collect();
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Self {
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v: 1,
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title: title.playlist.clone(),
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duration: title.duration_secs,
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streams,
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}
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}
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/// Convert back to a library Title (for remux).
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pub fn to_title(&self) -> DiscTitle {
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let streams = self
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.streams
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.iter()
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.map(|s| match s {
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MetaStream::Video {
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pid,
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codec,
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resolution,
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frame_rate,
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hdr,
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label,
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secondary,
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} => Stream::Video(VideoStream {
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pid: *pid,
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codec: codec.parse().unwrap(),
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resolution: resolution.parse().unwrap(),
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frame_rate: frame_rate.parse().unwrap(),
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hdr: hdr.parse().unwrap(),
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color_space: ColorSpace::Bt709,
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secondary: *secondary,
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label: label.clone(),
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}),
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MetaStream::Audio {
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pid,
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codec,
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channels,
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language,
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sample_rate,
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label,
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secondary,
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} => Stream::Audio(AudioStream {
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pid: *pid,
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codec: codec.parse().unwrap(),
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channels: channels.parse().unwrap(),
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language: language.clone(),
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sample_rate: sample_rate.parse().unwrap(),
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secondary: *secondary,
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label: label.clone(),
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}),
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MetaStream::Subtitle {
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pid,
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codec,
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language,
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forced,
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} => Stream::Subtitle(SubtitleStream {
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pid: *pid,
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codec: codec.parse().unwrap(),
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language: language.clone(),
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forced: *forced,
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codec_data: None,
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}),
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})
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.collect();
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DiscTitle {
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playlist: self.title.clone(),
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playlist_id: 0,
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duration_secs: self.duration,
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size_bytes: 0,
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clips: Vec::new(),
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streams,
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chapters: Vec::new(),
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extents: Vec::new(),
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content_format: crate::disc::ContentFormat::BdTs,
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}
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}
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}
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/// Write the metadata header to a writer. Padded to 192-byte boundary.
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pub fn write_header(w: &mut impl Write, meta: &M2tsMeta) -> io::Result<()> {
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let json = serde_json::to_vec(meta).map_err(io::Error::other)?;
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let json_len = json.len() as u32;
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let raw_len = 8 + 4 + json.len(); // magic + len + json
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let padded_len = raw_len.div_ceil(PACKET_SIZE) * PACKET_SIZE;
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let padding = padded_len - raw_len;
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w.write_all(&MAGIC)?;
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w.write_all(&json_len.to_be_bytes())?;
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w.write_all(&json)?;
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if padding > 0 {
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w.write_all(&vec![0u8; padding])?;
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}
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Ok(())
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}
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/// Try to read a metadata header from the start of an m2ts file.
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/// Returns None for bare m2ts files (no header).
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/// On success, leaves reader positioned at the first TS packet.
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/// On failure, seeks back to the start.
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pub fn read_header<R: Read + Seek>(r: &mut R) -> io::Result<Option<M2tsMeta>> {
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let start = r.stream_position()?;
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let mut magic = [0u8; 8];
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if r.read_exact(&mut magic).is_err() {
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r.seek(SeekFrom::Start(start))?;
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return Ok(None);
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}
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if magic[..4] != MAGIC[..4] {
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// Not a freemkv m2ts — seek back
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r.seek(SeekFrom::Start(start))?;
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return Ok(None);
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}
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let mut len_buf = [0u8; 4];
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r.read_exact(&mut len_buf)?;
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let json_len = u32::from_be_bytes(len_buf) as usize;
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let mut json_buf = vec![0u8; json_len];
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r.read_exact(&mut json_buf)?;
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let meta: M2tsMeta = serde_json::from_slice(&json_buf)
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.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
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// Skip padding to next 192-byte boundary
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let raw_len = 8 + 4 + json_len;
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let padded_len = raw_len.div_ceil(PACKET_SIZE) * PACKET_SIZE;
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let padding = padded_len - raw_len;
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if padding > 0 {
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r.seek(SeekFrom::Current(padding as i64))?;
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}
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Ok(Some(meta))
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}
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/// Read a metadata header from a forward-only stream (no Seek required).
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/// Returns None if the magic bytes don't match. Consumes the header bytes.
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pub fn read_header_from_stream(r: &mut impl Read) -> io::Result<Option<M2tsMeta>> {
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let mut magic = [0u8; 8];
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r.read_exact(&mut magic)?;
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if magic[..4] != MAGIC[..4] {
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return Ok(None);
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}
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let mut len_buf = [0u8; 4];
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r.read_exact(&mut len_buf)?;
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let json_len = u32::from_be_bytes(len_buf) as usize;
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let mut json_buf = vec![0u8; json_len];
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r.read_exact(&mut json_buf)?;
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let meta: M2tsMeta = serde_json::from_slice(&json_buf)
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.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
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// Skip padding
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let raw_len = 8 + 4 + json_len;
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let padded_len = raw_len.div_ceil(PACKET_SIZE) * PACKET_SIZE;
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let padding = padded_len - raw_len;
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if padding > 0 {
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let mut skip = vec![0u8; padding];
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r.read_exact(&mut skip)?;
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}
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Ok(Some(meta))
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}
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// Serialization uses Codec::id() / HdrFormat::id() and Display impls.
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// Deserialization uses FromStr impls (.parse()) on each enum.
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