scuffle_mp4/boxes/types/
sbgp.rs

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)]
/// Sample to Group Box
/// ISO/IEC 14496-12:2022(E) - 8.9.2
pub struct Sbgp {
    pub header: FullBoxHeader,
    pub grouping_type: Option<u32>,
    pub entries: Vec<SbgpEntry>,
}

#[derive(Debug, Clone, PartialEq)]
pub struct SbgpEntry {
    pub sample_count: u32,
    pub group_description_index: u32,
}

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

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

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

        let grouping_type = if header.version == 1 {
            Some(data.read_u32::<BigEndian>()?)
        } else {
            None
        };
        let entry_count = data.read_u32::<BigEndian>()?;

        let mut entries = Vec::with_capacity(entry_count as usize);

        for _ in 0..entry_count {
            let sample_count = data.read_u32::<BigEndian>()?;
            let group_description_index = data.read_u32::<BigEndian>()?;

            entries.push(SbgpEntry {
                sample_count,
                group_description_index,
            });
        }

        Ok(Self {
            header,
            grouping_type,
            entries,
        })
    }

    fn primitive_size(&self) -> u64 {
        self.header.size()
        + 4  // grouping_type
        + 4 // entry_count
        + (self.entries.len() as u64 * 8) // entries
    }

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

        if let Some(grouping_type) = self.grouping_type {
            writer.write_u32::<BigEndian>(grouping_type)?;
        }

        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;

        for entry in &self.entries {
            writer.write_u32::<BigEndian>(entry.sample_count)?;
            writer.write_u32::<BigEndian>(entry.group_description_index)?;
        }

        Ok(())
    }

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

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

        if self.header.version == 1 && self.grouping_type.is_none() {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                "sbgp box grouping_type must be present when version is 1",
            ));
        } else if self.header.version == 0 && self.grouping_type.is_some() {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                "sbgp box grouping_type must not be present when version is 0",
            ));
        }

        Ok(())
    }
}
scuffle_mp4/boxes/types/sbgp.rs

scuffle_mp4/boxes/types/
sbgp.rs
