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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2024 metamuffin <metamuffin.org>
*/
use crate::seek_index::get_seek_index;
use anyhow::{anyhow, bail};
use jellycommon::LocalTrack;
use jellymatroska::{block::Block, read::EbmlReader, Master, MatroskaTag};
use log::debug;
use std::{fs::File, io::BufReader, path::PathBuf};
pub fn extract_track(
path_base: PathBuf,
track_info: LocalTrack,
) -> anyhow::Result<Vec<(u64, u64, Vec<u8>)>> {
let source_path = path_base.join(track_info.path);
let file = File::open(&source_path)?;
let mut reader = EbmlReader::new(BufReader::new(file));
let index = get_seek_index(&source_path)?;
let index = index
.get(&(track_info.track as u64))
.ok_or(anyhow!("track missing"))?;
let mut out = Vec::new();
for b in &index.blocks {
reader.seek(b.source_off, MatroskaTag::BlockGroup(Master::Start))?;
let (duration, block) = read_group(&mut reader)?;
assert_eq!(
track_info.track, block.track as usize,
"seek index is wrong"
);
out.push((b.pts, duration, block.data))
}
Ok(out)
}
pub fn read_group(segment: &mut EbmlReader) -> anyhow::Result<(u64, Block)> {
let (mut dur, mut block) = (None, None);
for _ in 0..10 {
let (_, item) = segment.next().ok_or(anyhow!("eof"))??;
match item {
MatroskaTag::Void(_) => (),
MatroskaTag::Crc32(_) => (),
MatroskaTag::Cluster(_) => bail!("unexpected cluster"),
MatroskaTag::Timestamp(_) => (),
MatroskaTag::SimpleBlock(block) => {
return Ok((1000, block)); // HDMV/PGS does not use duration?!
}
MatroskaTag::BlockGroup(Master::Start) => (),
MatroskaTag::BlockGroup(Master::End) => return Ok((dur.unwrap(), block.unwrap())),
MatroskaTag::BlockDuration(duration) => dur = Some(duration),
MatroskaTag::Block(blk) => block = Some(blk),
MatroskaTag::Cues(_) => bail!("reached cues, this is the end"),
MatroskaTag::Segment(Master::End) => bail!("extractor reached segment end"),
_ => debug!("(rs) tag ignored: {item:?}"),
}
}
bail!(".")
}
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