scuffle_mp4/boxes/types/
ctts.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/// Composition Time to Sample Box
11/// ISO/IEC 14496-12:2022(E) - 8.6.1
12pub struct Ctts {
13    pub header: FullBoxHeader,
14    pub entries: Vec<CttsEntry>,
15}
16
17#[derive(Debug, Clone, PartialEq)]
18/// Entry in the Composition Time to Sample Box
19pub struct CttsEntry {
20    pub sample_count: u32,
21    pub sample_offset: i64,
22}
23
24impl BoxType for Ctts {
25    const NAME: [u8; 4] = *b"ctts";
26
27    fn demux(header: BoxHeader, data: Bytes) -> io::Result<Self> {
28        let mut reader = io::Cursor::new(data);
29
30        let header = FullBoxHeader::demux(header, &mut reader)?;
31
32        let entry_count = reader.read_u32::<BigEndian>()?;
33
34        let mut entries = Vec::with_capacity(entry_count as usize);
35
36        for _ in 0..entry_count {
37            let sample_count = reader.read_u32::<BigEndian>()?;
38            let sample_offset = if header.version == 1 {
39                reader.read_i32::<BigEndian>()? as i64
40            } else {
41                reader.read_u32::<BigEndian>()? as i64
42            };
43
44            entries.push(CttsEntry {
45                sample_count,
46                sample_offset,
47            });
48        }
49
50        Ok(Self { header, entries })
51    }
52
53    fn primitive_size(&self) -> u64 {
54        self.header.size()
55        + 4 // entry_count
56        + (self.entries.len() as u64 * 8) // entries
57    }
58
59    fn primitive_mux<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
60        self.header.mux(writer)?;
61
62        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
63
64        for entry in &self.entries {
65            writer.write_u32::<BigEndian>(entry.sample_count)?;
66
67            if self.header.version == 1 {
68                writer.write_i32::<BigEndian>(entry.sample_offset as i32)?;
69            } else {
70                writer.write_u32::<BigEndian>(entry.sample_offset as u32)?;
71            }
72        }
73
74        Ok(())
75    }
76
77    fn validate(&self) -> io::Result<()> {
78        if self.header.flags != 0 {
79            return Err(io::Error::new(io::ErrorKind::InvalidData, "ctts flags must be 0"));
80        }
81
82        if self.header.version > 1 {
83            return Err(io::Error::new(io::ErrorKind::InvalidData, "ctts version must be 0 or 1"));
84        }
85
86        Ok(())
87    }
88}
scuffle_mp4/boxes/types/ctts.rs

scuffle_mp4/boxes/types/
ctts.rs
