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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) 2025 metamuffin <metamuffin.org>
*/
use anyhow::{anyhow, bail, Result};
use jellymatroska::{block::Block, read::EbmlReader, Master, MatroskaTag};
use log::{debug, info, trace};
pub struct SegmentExtractIter<'a> {
segment: &'a mut EbmlReader,
extract: u64,
}
impl<'a> SegmentExtractIter<'a> {
pub fn new(segment: &'a mut EbmlReader, extract: u64) -> Self {
Self { segment, extract }
}
/// Returns the next block and sometimes its duration too.
pub fn next_block(&mut self) -> Result<(Block, Option<u64>)> {
let mut duration = None;
let mut group = false;
let mut saved_block = None;
loop {
let (_, item) = self.segment.next().ok_or(anyhow!("eof"))??;
match item {
MatroskaTag::Void(_) => (),
MatroskaTag::Crc32(_) => (),
MatroskaTag::Cluster(_) => (),
MatroskaTag::Timestamp(_) => (),
MatroskaTag::BlockGroup(Master::Start) => group = true,
MatroskaTag::BlockGroup(Master::End) => {
if !group {
bail!("group end without start");
}
if let Some(block) = saved_block {
return Ok((block, duration));
}
group = false;
}
MatroskaTag::BlockDuration(d) => duration = Some(d),
MatroskaTag::SimpleBlock(block) | MatroskaTag::Block(block) => {
if block.track == self.extract {
trace!("block: track={} tso={}", block.track, block.timestamp_off);
if group {
// can't return yet; there might be a BlockDuration coming
saved_block = Some(block);
} else {
return Ok((block, duration));
}
}
}
MatroskaTag::Cues(_) => bail!("reached cues, this is the end"),
MatroskaTag::Segment(Master::End) => info!("extractor reached segment end"),
_ => debug!("(rs) tag ignored: {item:?}"),
}
}
}
}
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