mp4_atom/moov/trak/
tref.rs

1use crate::*;
2
3/// Track reference type box.
4///
5/// We treat this as Atom-like, but in a distinct namespace, consistent
6/// with the way MP4RA handles it. Avoids collisions between real boxes,
7/// and reference item labels
8#[derive(Debug, Clone, PartialEq, Eq)]
9#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
10pub struct TrackReferenceTypeBox {
11    pub reference_type: FourCC,
12    pub track_ids: Vec<u32>,
13}
14
15impl TrackReferenceTypeBox {
16    fn encode<B: BufMut>(&self, buf: &mut B) -> Result<()> {
17        if self.track_ids.len() * 4 > (u32::MAX as usize) - 8 {
18            // its ludicrous
19            return Err(Error::InvalidSize);
20        }
21        let size: u32 = 4u32 + 4u32 + (self.track_ids.len() as u32) * 4;
22        size.encode(buf)?;
23        self.reference_type.encode(buf)?;
24        self.track_ids.encode(buf)
25    }
26
27    fn decode<B: Buf>(buf: &mut B) -> Result<TrackReferenceTypeBox> {
28        let header = Header::decode(buf)?;
29        let size = header.size.unwrap_or(buf.remaining());
30        if size > buf.remaining() {
31            return Err(Error::InvalidSize);
32        }
33        let num_entries = size / 4; // since its all u32
34        let mut track_ids = Vec::with_capacity(num_entries.min(16));
35        for _ in 0..num_entries {
36            track_ids.push(u32::decode(buf)?);
37        }
38        // ignore any residual bytes unless we're in strict mode
39        if cfg!(feature = "strict") && (size % 4 != 0) {
40            return Err(Error::InvalidSize);
41        }
42        buf.advance(size % 4);
43        Ok(TrackReferenceTypeBox {
44            reference_type: header.kind,
45            track_ids,
46        })
47    }
48}
49
50/// Track reference box
51#[derive(Debug, Clone, PartialEq, Eq, Default)]
52#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
53pub struct Tref {
54    pub track_reference_type_boxes: Vec<TrackReferenceTypeBox>,
55}
56
57impl Atom for Tref {
58    const KIND: FourCC = FourCC::new(b"tref");
59
60    fn decode_body<B: Buf>(buf: &mut B) -> Result<Self> {
61        let mut track_reference_type_boxes = vec![];
62        while buf.has_remaining() {
63            let reference = TrackReferenceTypeBox::decode(buf)?;
64            track_reference_type_boxes.push(reference);
65        }
66        Ok(Self {
67            track_reference_type_boxes,
68        })
69    }
70
71    fn encode_body<B: BufMut>(&self, buf: &mut B) -> Result<()> {
72        for b in &self.track_reference_type_boxes {
73            b.encode(buf)?;
74        }
75        Ok(())
76    }
77}
78
79#[cfg(test)]
80mod tests {
81    use super::*;
82
83    // From the 01_simple.mp4 sample in MPEG's file format conformance set
84    const ENCODED_TREF: &[u8] = &[
85        0x00, 0x00, 0x00, 0x24, 0x74, 0x72, 0x65, 0x66, 0x00, 0x00, 0x00, 0x0c, 0x73, 0x79, 0x6e,
86        0x63, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x10, 0x6d, 0x70, 0x6f, 0x64, 0x00, 0x00,
87        0x00, 0xc9, 0x00, 0x00, 0x00, 0x65,
88    ];
89
90    #[test]
91    fn test_tref_decode() {
92        let buf: &mut std::io::Cursor<&&[u8]> = &mut std::io::Cursor::new(&ENCODED_TREF);
93
94        let tref = Tref::decode(buf).expect("failed to decode tref");
95
96        assert_eq!(
97            tref,
98            Tref {
99                track_reference_type_boxes: vec![
100                    TrackReferenceTypeBox {
101                        reference_type: b"sync".into(),
102                        track_ids: vec![1]
103                    },
104                    TrackReferenceTypeBox {
105                        reference_type: b"mpod".into(),
106                        track_ids: vec![201, 101]
107                    }
108                ]
109            }
110        );
111    }
112
113    #[test]
114    fn test_tref_encode() {
115        let tref = Tref {
116            track_reference_type_boxes: vec![
117                TrackReferenceTypeBox {
118                    reference_type: b"sync".into(),
119                    track_ids: vec![1],
120                },
121                TrackReferenceTypeBox {
122                    reference_type: b"mpod".into(),
123                    track_ids: vec![201, 101],
124                },
125            ],
126        };
127
128        let mut buf = Vec::new();
129        tref.encode(&mut buf).unwrap();
130
131        assert_eq!(buf.as_slice(), ENCODED_TREF);
132    }
133}
mp4_atom/moov/trak/tref.rs

mp4_atom/moov/trak/
tref.rs
