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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 crate::{
read::ReadExt,
write::{vint_length, write_vint},
ReadValue, Result, WriteValue,
};
use std::io::{Cursor, Write};
#[derive(Debug, PartialEq, Clone, Copy)]
pub enum LacingType {
Xiph,
FixedSize,
Ebml,
}
#[derive(Debug, PartialEq, Clone)]
pub struct Block {
pub track: u64,
pub keyframe: bool,
pub discardable: bool,
pub timestamp_off: i16,
pub invisible: bool,
pub lacing: Option<LacingType>,
pub data: Vec<u8>,
}
impl ReadValue for Block {
fn from_buf(buf: &[u8]) -> Result<Self> {
let (track, c) = Cursor::new(buf).read_vint_len()?;
let timestamp_off = i16::from_be_bytes(buf[c..c + 2].try_into().unwrap());
let flags = buf[c + 2];
let data = Vec::from(&buf[c + 3..]);
let invisible = (flags & 0b1000) == 0b1000;
let lacing = match flags & 0b110 {
0b000 => None,
0b010 => Some(LacingType::Xiph),
0b100 => Some(LacingType::FixedSize),
0b110 => Some(LacingType::Ebml),
_ => unreachable!(),
};
let keyframe = (flags & 0b10000000) == 0b10000000;
let discardable = (flags & 0b1) == 0b1;
Ok(Self {
keyframe,
discardable,
track,
data,
invisible,
lacing,
timestamp_off,
})
}
}
impl WriteValue for Block {
fn write_to(&self, w: &mut impl Write) -> Result<()> {
write_vint(w, self.inner_len() as u64)?;
write_vint(w, self.track)?;
w.write_all(&self.timestamp_off.to_be_bytes())?;
w.write_all(&[match self.discardable {
true => 0b1,
false => 0b0,
} | match self.keyframe {
true => 0b10000000,
false => 0b00000000,
} | match self.invisible {
true => 0b1000,
false => 0b0000,
} | match self.lacing {
Some(LacingType::Xiph) => 0b010,
Some(LacingType::Ebml) => 0b100,
Some(LacingType::FixedSize) => 0b110,
None => 0b0000,
}])?;
w.write_all(&self.data)?;
Ok(())
}
fn size(&self) -> usize {
let il = self.inner_len();
vint_length(il as u64) + il
}
}
impl Block {
fn inner_len(&self) -> usize {
vint_length(self.track)
+ 2 // timestamp
+ 1 // flags
+ self.data.len()
}
}
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