scuffle_mp4/boxes/types/
tfdt.rs

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use std::io;

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

use crate::boxes::header::{BoxHeader, FullBoxHeader};
use crate::boxes::traits::BoxType;

#[derive(Debug, Clone, PartialEq)]
/// Track Fragment Base Media Decode Time Box
/// ISO/IEC 14496-12:2022(E) - 8.8.12
pub struct Tfdt {
    pub header: FullBoxHeader,
    pub base_media_decode_time: u64,
}

impl Tfdt {
    pub fn new(base_media_decode_time: u64) -> Self {
        let version = if base_media_decode_time > u32::MAX as u64 { 1 } else { 0 };

        Self {
            header: FullBoxHeader::new(Self::NAME, version, 0),
            base_media_decode_time,
        }
    }
}

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

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

        let header = FullBoxHeader::demux(header, &mut reader)?;

        let base_media_decode_time = if header.version == 1 {
            reader.read_u64::<BigEndian>()?
        } else {
            reader.read_u32::<BigEndian>()? as u64
        };

        Ok(Self {
            header,
            base_media_decode_time,
        })
    }

    fn primitive_size(&self) -> u64 {
        self.header.size() + if self.header.version == 1 { 8 } else { 4 }
    }

    fn primitive_mux<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
        self.header.mux(writer)?;

        if self.header.version == 1 {
            writer.write_u64::<BigEndian>(self.base_media_decode_time)?;
        } else {
            writer.write_u32::<BigEndian>(self.base_media_decode_time as u32)?;
        }

        Ok(())
    }

    fn validate(&self) -> io::Result<()> {
        if self.header.version > 1 {
            return Err(io::Error::new(io::ErrorKind::InvalidData, "tfdt version must be 0 or 1"));
        }

        if self.header.flags != 0 {
            return Err(io::Error::new(io::ErrorKind::InvalidData, "tfdt flags must be 0"));
        }

        if self.header.version == 0 && self.base_media_decode_time > u32::MAX as u64 {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                "tfdt base_data_offset must be less than 2^32",
            ));
        }

        Ok(())
    }
}