scuffle_mp4/boxes/types/
btrt.rs

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use std::io;

use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use bytes::Bytes;

use crate::boxes::header::BoxHeader;
use crate::boxes::traits::BoxType;

#[derive(Debug, Clone, PartialEq)]
/// BitRate Box
/// ISO/IEC 14496-12:2022(E) - 8.5.2
pub struct Btrt {
    pub header: BoxHeader,
    pub buffer_size_db: u32,
    pub max_bitrate: u32,
    pub avg_bitrate: u32,
}

impl BoxType for Btrt {
    const NAME: [u8; 4] = *b"btrt";

    fn demux(header: BoxHeader, data: Bytes) -> io::Result<Self> {
        let mut reader = io::Cursor::new(data);

        let buffer_size_db = reader.read_u32::<BigEndian>()?;
        let max_bitrate = reader.read_u32::<BigEndian>()?;
        let avg_bitrate = reader.read_u32::<BigEndian>()?;

        Ok(Self {
            header,

            buffer_size_db,
            max_bitrate,
            avg_bitrate,
        })
    }

    fn primitive_size(&self) -> u64 {
        4 // buffer_size_db
        + 4 // max_bitrate
        + 4 // avg_bitrate
    }

    fn primitive_mux<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
        writer.write_u32::<BigEndian>(self.buffer_size_db)?;
        writer.write_u32::<BigEndian>(self.max_bitrate)?;
        writer.write_u32::<BigEndian>(self.avg_bitrate)?;

        Ok(())
    }
}