mp4/mp4box/
ctts.rs

1use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
2use serde::Serialize;
3use std::io::{Read, Seek, Write};
4use std::mem::size_of;
5
6use crate::mp4box::*;
7
8#[derive(Debug, Clone, PartialEq, Eq, Default, Serialize)]
9pub struct CttsBox {
10    pub version: u8,
11    pub flags: u32,
12
13    #[serde(skip_serializing)]
14    pub entries: Vec<CttsEntry>,
15}
16
17impl CttsBox {
18    pub fn get_type(&self) -> BoxType {
19        BoxType::CttsBox
20    }
21
22    pub fn get_size(&self) -> u64 {
23        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
24    }
25}
26
27#[derive(Debug, Clone, PartialEq, Eq, Default, Serialize)]
28pub struct CttsEntry {
29    pub sample_count: u32,
30    pub sample_offset: i32,
31}
32
33impl Mp4Box for CttsBox {
34    fn box_type(&self) -> BoxType {
35        self.get_type()
36    }
37
38    fn box_size(&self) -> u64 {
39        self.get_size()
40    }
41
42    fn to_json(&self) -> Result<String> {
43        Ok(serde_json::to_string(&self).unwrap())
44    }
45
46    fn summary(&self) -> Result<String> {
47        let s = format!("entries_count={}", self.entries.len());
48        Ok(s)
49    }
50}
51
52impl<R: Read + Seek> ReadBox<&mut R> for CttsBox {
53    fn read_box(reader: &mut R, size: u64) -> Result<Self> {
54        let start = box_start(reader)?;
55
56        let (version, flags) = read_box_header_ext(reader)?;
57
58        let header_size = HEADER_SIZE + HEADER_EXT_SIZE;
59        let entry_count = reader.read_u32::<BigEndian>()?;
60        let entry_size = size_of::<u32>() + size_of::<i32>(); // sample_count + sample_offset
61                                                              // (sample_offset might be a u32, but the size is the same.)
62        let other_size = size_of::<i32>(); // entry_count
63        if u64::from(entry_count)
64            > size
65                .saturating_sub(header_size)
66                .saturating_sub(other_size as u64)
67                / entry_size as u64
68        {
69            return Err(Error::InvalidData(
70                "ctts entry_count indicates more entries than could fit in the box",
71            ));
72        }
73        let mut entries = Vec::with_capacity(entry_count as usize);
74        for _ in 0..entry_count {
75            let entry = CttsEntry {
76                sample_count: reader.read_u32::<BigEndian>()?,
77                sample_offset: reader.read_i32::<BigEndian>()?,
78            };
79            entries.push(entry);
80        }
81
82        skip_bytes_to(reader, start + size)?;
83
84        Ok(CttsBox {
85            version,
86            flags,
87            entries,
88        })
89    }
90}
91
92impl<W: Write> WriteBox<&mut W> for CttsBox {
93    fn write_box(&self, writer: &mut W) -> Result<u64> {
94        let size = self.box_size();
95        BoxHeader::new(self.box_type(), size).write(writer)?;
96
97        write_box_header_ext(writer, self.version, self.flags)?;
98
99        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
100        for entry in self.entries.iter() {
101            writer.write_u32::<BigEndian>(entry.sample_count)?;
102            writer.write_i32::<BigEndian>(entry.sample_offset)?;
103        }
104
105        Ok(size)
106    }
107}
108
109#[cfg(test)]
110mod tests {
111    use super::*;
112    use crate::mp4box::BoxHeader;
113    use std::io::Cursor;
114
115    #[test]
116    fn test_ctts() {
117        let src_box = CttsBox {
118            version: 0,
119            flags: 0,
120            entries: vec![
121                CttsEntry {
122                    sample_count: 1,
123                    sample_offset: 200,
124                },
125                CttsEntry {
126                    sample_count: 2,
127                    sample_offset: -100,
128                },
129            ],
130        };
131        let mut buf = Vec::new();
132        src_box.write_box(&mut buf).unwrap();
133        assert_eq!(buf.len(), src_box.box_size() as usize);
134
135        let mut reader = Cursor::new(&buf);
136        let header = BoxHeader::read(&mut reader).unwrap();
137        assert_eq!(header.name, BoxType::CttsBox);
138        assert_eq!(src_box.box_size(), header.size);
139
140        let dst_box = CttsBox::read_box(&mut reader, header.size).unwrap();
141        assert_eq!(src_box, dst_box);
142    }
143}
mp4/mp4box/ctts.rs

mp4/mp4box/
ctts.rs
