scuffle_mp4/boxes/types/
stsc.rs

1use std::io;
2
3use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
4use bytes::Bytes;
5
6use crate::boxes::header::{BoxHeader, FullBoxHeader};
7use crate::boxes::traits::BoxType;
8
9#[derive(Debug, Clone, PartialEq)]
10/// Sample To Chunk Box
11/// ISO/IEC 14496-12:2022(E) - 8.7.4
12pub struct Stsc {
13    pub header: FullBoxHeader,
14    pub entries: Vec<StscEntry>,
15}
16
17impl Stsc {
18    pub fn new(entries: Vec<StscEntry>) -> Self {
19        Self {
20            header: FullBoxHeader::new(Self::NAME, 0, 0),
21            entries,
22        }
23    }
24}
25
26#[derive(Debug, Clone, PartialEq)]
27/// Sample To Chunk Entry
28pub struct StscEntry {
29    pub first_chunk: u32,
30    pub samples_per_chunk: u32,
31    pub sample_description_index: u32,
32}
33
34impl BoxType for Stsc {
35    const NAME: [u8; 4] = *b"stsc";
36
37    fn demux(header: BoxHeader, data: Bytes) -> io::Result<Self> {
38        let mut reader = io::Cursor::new(data);
39
40        let header = FullBoxHeader::demux(header, &mut reader)?;
41
42        let entry_count = reader.read_u32::<BigEndian>()?;
43        let mut entries = Vec::with_capacity(entry_count as usize);
44        for _ in 0..entry_count {
45            let first_chunk = reader.read_u32::<BigEndian>()?;
46            let samples_per_chunk = reader.read_u32::<BigEndian>()?;
47            let sample_description_index = reader.read_u32::<BigEndian>()?;
48
49            entries.push(StscEntry {
50                first_chunk,
51                samples_per_chunk,
52                sample_description_index,
53            });
54        }
55
56        Ok(Self { header, entries })
57    }
58
59    fn primitive_size(&self) -> u64 {
60        let size = self.header.size();
61        let size = size + 4; // entry_count
62        // entries
63        size + (self.entries.len() as u64 * 12)
64    }
65
66    fn primitive_mux<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
67        self.header.mux(writer)?;
68
69        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
70        for entry in &self.entries {
71            writer.write_u32::<BigEndian>(entry.first_chunk)?;
72            writer.write_u32::<BigEndian>(entry.samples_per_chunk)?;
73            writer.write_u32::<BigEndian>(entry.sample_description_index)?;
74        }
75
76        Ok(())
77    }
78
79    fn validate(&self) -> io::Result<()> {
80        if self.header.version != 0 {
81            return Err(io::Error::new(io::ErrorKind::InvalidData, "stsc box version must be 0"));
82        }
83
84        if self.header.flags != 0 {
85            return Err(io::Error::new(io::ErrorKind::InvalidData, "stsc box flags must be 0"));
86        }
87
88        Ok(())
89    }
90}
scuffle_mp4/boxes/types/stsc.rs

scuffle_mp4/boxes/types/
stsc.rs
