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use crate::{read::ReadExt, write::write_vint};
use anyhow::Result;
use std::io::Cursor;
pub enum LacingType {
FixedSize,
Ebml,
Xiph,
}
pub struct Block {
pub track: u64,
pub timestamp_off: i16,
pub invisible: bool,
pub lacing: Option<LacingType>,
pub data: Vec<u8>,
}
impl Block {
pub fn parse(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 & 0b10000) == 0b10000;
let lacing = match flags & 0b1100 {
0b0000 => None,
0b0100 => Some(LacingType::Xiph),
0b1000 => Some(LacingType::Ebml),
0b1100 => Some(LacingType::FixedSize),
_ => unreachable!(),
};
Ok(Self {
track,
data,
invisible,
lacing,
timestamp_off,
})
}
pub fn dump(&self) -> Vec<u8> {
let mut out = vec![];
write_vint(&mut out, self.track).unwrap();
out.extend(self.timestamp_off.to_be_bytes().into_iter());
out.push(
match self.invisible {
true => 0b10000,
false => 0b00000,
} | match self.lacing {
Some(LacingType::Xiph) => 0b0100,
Some(LacingType::Ebml) => 0b1000,
Some(LacingType::FixedSize) => 0b1100,
None => 0b0000,
},
);
out
}
}
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