mp4/mp4box/
stts.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 SttsBox {
10    pub version: u8,
11    pub flags: u32,
12
13    #[serde(skip_serializing)]
14    pub entries: Vec<SttsEntry>,
15}
16
17impl SttsBox {
18    pub fn get_type(&self) -> BoxType {
19        BoxType::SttsBox
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 SttsEntry {
29    pub sample_count: u32,
30    pub sample_delta: u32,
31}
32
33impl Mp4Box for SttsBox {
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={}", self.entries.len());
48        Ok(s)
49    }
50}
51
52impl<R: Read + Seek> ReadBox<&mut R> for SttsBox {
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 other_size = size_of::<u32>(); // entry_count
60        let entry_size = size_of::<u32>() + size_of::<u32>(); // sample_count + sample_delta
61        let entry_count = reader.read_u32::<BigEndian>()?;
62        if u64::from(entry_count)
63            > size
64                .saturating_sub(header_size)
65                .saturating_sub(other_size as u64)
66                / entry_size as u64
67        {
68            return Err(Error::InvalidData(
69                "stts entry_count indicates more entries than could fit in the box",
70            ));
71        }
72        let mut entries = Vec::with_capacity(entry_count as usize);
73        for _i in 0..entry_count {
74            let entry = SttsEntry {
75                sample_count: reader.read_u32::<BigEndian>()?,
76                sample_delta: reader.read_u32::<BigEndian>()?,
77            };
78            entries.push(entry);
79        }
80
81        skip_bytes_to(reader, start + size)?;
82
83        Ok(SttsBox {
84            version,
85            flags,
86            entries,
87        })
88    }
89}
90
91impl<W: Write> WriteBox<&mut W> for SttsBox {
92    fn write_box(&self, writer: &mut W) -> Result<u64> {
93        let size = self.box_size();
94        BoxHeader::new(self.box_type(), size).write(writer)?;
95
96        write_box_header_ext(writer, self.version, self.flags)?;
97
98        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
99        for entry in self.entries.iter() {
100            writer.write_u32::<BigEndian>(entry.sample_count)?;
101            writer.write_u32::<BigEndian>(entry.sample_delta)?;
102        }
103
104        Ok(size)
105    }
106}
107
108#[cfg(test)]
109mod tests {
110    use super::*;
111    use crate::mp4box::BoxHeader;
112    use std::io::Cursor;
113
114    #[test]
115    fn test_stts() {
116        let src_box = SttsBox {
117            version: 0,
118            flags: 0,
119            entries: vec![
120                SttsEntry {
121                    sample_count: 29726,
122                    sample_delta: 1024,
123                },
124                SttsEntry {
125                    sample_count: 1,
126                    sample_delta: 512,
127                },
128            ],
129        };
130        let mut buf = Vec::new();
131        src_box.write_box(&mut buf).unwrap();
132        assert_eq!(buf.len(), src_box.box_size() as usize);
133
134        let mut reader = Cursor::new(&buf);
135        let header = BoxHeader::read(&mut reader).unwrap();
136        assert_eq!(header.name, BoxType::SttsBox);
137        assert_eq!(src_box.box_size(), header.size);
138
139        let dst_box = SttsBox::read_box(&mut reader, header.size).unwrap();
140        assert_eq!(src_box, dst_box);
141    }
142}
mp4/mp4box/stts.rs

mp4/mp4box/
stts.rs
