scuffle_mp4/boxes/types/
elst.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/// Edit List Box
11/// ISO/IEC 14496-12:2022(E) - 8.6.6
12pub struct Elst {
13    pub header: FullBoxHeader,
14    pub entries: Vec<ElstEntry>,
15}
16
17impl Elst {
18    pub fn new(entries: Vec<ElstEntry>) -> Self {
19        Self {
20            header: FullBoxHeader::new(Self::NAME, 0, 0),
21            entries,
22        }
23    }
24}
25
26#[derive(Debug, Clone, PartialEq)]
27/// Entry in the Edit List Box
28pub struct ElstEntry {
29    pub segment_duration: u64,
30    pub media_time: i64,
31    pub media_rate_integer: i16,
32    pub media_rate_fraction: i16,
33}
34
35impl BoxType for Elst {
36    const NAME: [u8; 4] = *b"elst";
37
38    fn demux(header: BoxHeader, data: Bytes) -> io::Result<Self> {
39        let mut reader = io::Cursor::new(data);
40
41        let header = FullBoxHeader::demux(header, &mut reader)?;
42
43        let entry_count = reader.read_u32::<BigEndian>()?;
44
45        let mut entries = Vec::with_capacity(entry_count as usize);
46
47        for _ in 0..entry_count {
48            let (segment_duration, media_time, media_rate_integer, media_rate_fraction) = if header.version == 1 {
49                (
50                    reader.read_u64::<BigEndian>()?, // segment_duration
51                    reader.read_i64::<BigEndian>()?, // media_time
52                    reader.read_i16::<BigEndian>()?, // media_rate_integer
53                    reader.read_i16::<BigEndian>()?, // media_rate_fraction
54                )
55            } else {
56                (
57                    reader.read_u32::<BigEndian>()? as u64, // segment_duration
58                    reader.read_i32::<BigEndian>()? as i64, // media_time
59                    reader.read_i16::<BigEndian>()?,        // media_rate_integer
60                    reader.read_i16::<BigEndian>()?,        // media_rate_fraction
61                )
62            };
63
64            entries.push(ElstEntry {
65                segment_duration,
66                media_time,
67                media_rate_integer,
68                media_rate_fraction,
69            });
70        }
71
72        Ok(Self { header, entries })
73    }
74
75    fn primitive_size(&self) -> u64 {
76        self.header.size()
77        + 4 // entry_count
78        + (self.entries.len() as u64) * if self.header.version == 1 {
79            8 + 8 + 2 + 2 // segment_duration + media_time + media_rate_integer + media_rate_fraction
80        } else {
81            4 + 4 + 2 + 2 // segment_duration + media_time + media_rate_integer + media_rate_fraction
82        }
83    }
84
85    fn primitive_mux<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
86        self.header.mux(writer)?;
87
88        writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
89
90        for entry in &self.entries {
91            if self.header.version == 1 {
92                writer.write_u64::<BigEndian>(entry.segment_duration)?;
93                writer.write_i64::<BigEndian>(entry.media_time)?;
94            } else {
95                writer.write_u32::<BigEndian>(entry.segment_duration as u32)?;
96                writer.write_i32::<BigEndian>(entry.media_time as i32)?;
97            }
98
99            writer.write_i16::<BigEndian>(entry.media_rate_integer)?;
100            writer.write_i16::<BigEndian>(entry.media_rate_fraction)?;
101        }
102
103        Ok(())
104    }
105
106    fn validate(&self) -> io::Result<()> {
107        if self.header.flags != 0 {
108            return Err(io::Error::new(io::ErrorKind::InvalidData, "elst: version 1 is not supported"));
109        }
110
111        if self.header.version > 1 {
112            return Err(io::Error::new(io::ErrorKind::InvalidData, "elst: version must be 0 or 1"));
113        }
114
115        if self.header.version == 1 {
116            for entry in &self.entries {
117                if entry.segment_duration > u32::MAX as u64 {
118                    return Err(io::Error::new(
119                        io::ErrorKind::InvalidData,
120                        "elst: segment_duration must be u32",
121                    ));
122                }
123
124                if entry.media_time > i32::MAX as i64 {
125                    return Err(io::Error::new(io::ErrorKind::InvalidData, "elst: media_time must be i32"));
126                }
127            }
128        }
129
130        Ok(())
131    }
132}
scuffle_mp4/boxes/types/elst.rs

scuffle_mp4/boxes/types/
elst.rs
