mp4-edit 0.1.1

mp4 read/write library designed with audiobooks in mind
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212

use bon::Builder;

use std::time::Duration;

use crate::{
    atom::{
        util::{mp4_timestamp_now, scaled_duration, unscaled_duration},
        FourCC,
    },
    parser::ParseAtomData,
    writer::SerializeAtom,
    ParseError,
};

pub const MVHD: FourCC = FourCC::new(b"mvhd");

#[derive(Debug, Clone, Builder)]
pub struct MovieHeaderAtom {
    /// Version of the mvhd atom format (0 or 1)
    #[builder(default = 0)]
    pub version: u8,
    /// Flags for the mvhd atom (usually all zeros)
    #[builder(default = [0u8; 3])]
    pub flags: [u8; 3],
    /// When the movie was created (seconds since Jan 1, 1904 UTC)
    #[builder(default = mp4_timestamp_now())]
    pub creation_time: u64,
    /// When the movie was last modified (seconds since Jan 1, 1904 UTC)
    #[builder(default = mp4_timestamp_now())]
    pub modification_time: u64,
    /// Number of time units per second (e.g., 90000 for 90kHz)
    pub timescale: u32,
    /// Duration of the movie in timescale units
    pub duration: u64,
    /// Playback rate (1.0 = normal speed, 2.0 = double speed)
    #[builder(default = 1.0)]
    pub rate: f32,
    /// Audio volume level (1.0 = full volume, 0.0 = muted)
    #[builder(default = 1.0)]
    pub volume: f32,
    #[builder(default)]
    pub reserved: [u8; 10],
    /// 3x3 transformation matrix for video display positioning/rotation
    pub matrix: Option<[i32; 9]>,
    /// Time when preview starts (in timescale units)
    #[builder(default = 0)]
    pub preview_time: u32,
    /// Duration of the preview (in timescale units)
    #[builder(default = 0)]
    pub preview_duration: u32,
    /// Time of poster frame to display when movie is not playing
    #[builder(default = 0)]
    pub poster_time: u32,
    /// Start time of current selection (in timescale units)
    #[builder(default = 0)]
    pub selection_time: u32,
    /// Duration of current selection (in timescale units)
    #[builder(default = 0)]
    pub selection_duration: u32,
    /// Current playback time position (in timescale units)
    #[builder(default = 0)]
    pub current_time: u32,
    /// ID to use for the next track added to this movie
    pub next_track_id: u32,
}

impl MovieHeaderAtom {
    pub fn update_duration<F>(&mut self, mut closure: F) -> &mut Self
    where
        F: FnMut(Duration) -> Duration,
    {
        self.duration = scaled_duration(
            closure(unscaled_duration(self.duration, u64::from(self.timescale))),
            u64::from(self.timescale),
        );
        self
    }

    pub fn duration(&self) -> Duration {
        unscaled_duration(self.duration, u64::from(self.timescale))
    }
}

impl ParseAtomData for MovieHeaderAtom {
    fn parse_atom_data(atom_type: FourCC, input: &[u8]) -> Result<Self, ParseError> {
        crate::atom::util::parser::assert_atom_type!(atom_type, MVHD);
        use crate::atom::util::parser::stream;
        use winnow::Parser;
        Ok(parser::parse_mvhd_data.parse(stream(input))?)
    }
}

impl SerializeAtom for MovieHeaderAtom {
    fn atom_type(&self) -> FourCC {
        MVHD
    }

    fn into_body_bytes(self) -> Vec<u8> {
        serializer::serialize_mvhd_atom(self)
    }
}

mod serializer {
    use crate::atom::util::serializer::{fixed_point_16x16, fixed_point_8x8};

    use super::MovieHeaderAtom;

    pub fn serialize_mvhd_atom(mvhd: MovieHeaderAtom) -> Vec<u8> {
        let mut data = Vec::new();

        // Determine version based on whether values fit in 32-bit
        let needs_64_bit = mvhd.creation_time > u64::from(u32::MAX)
            || mvhd.modification_time > u64::from(u32::MAX)
            || mvhd.duration > u64::from(u32::MAX);

        let version: u8 = if needs_64_bit { 1 } else { 0 };

        let be_u32_or_u64 = |v: u64| match version {
            0 => u32::try_from(v).unwrap().to_be_bytes().to_vec(),
            1 => v.to_be_bytes().to_vec(),
            _ => unreachable!(),
        };

        data.extend(version.to_be_bytes());
        data.extend(mvhd.flags);
        data.extend(be_u32_or_u64(mvhd.creation_time));
        data.extend(be_u32_or_u64(mvhd.modification_time));
        data.extend(mvhd.timescale.to_be_bytes());
        data.extend(be_u32_or_u64(mvhd.duration));
        data.extend(fixed_point_16x16(mvhd.rate));
        data.extend(fixed_point_8x8(mvhd.volume));
        data.extend(mvhd.reserved);
        if let Some(matrix) = mvhd.matrix {
            for value in matrix {
                data.extend(value.to_be_bytes());
            }
        }
        data.extend_from_slice(&mvhd.preview_time.to_be_bytes());
        data.extend_from_slice(&mvhd.preview_duration.to_be_bytes());
        data.extend_from_slice(&mvhd.poster_time.to_be_bytes());
        data.extend_from_slice(&mvhd.selection_time.to_be_bytes());
        data.extend_from_slice(&mvhd.selection_duration.to_be_bytes());
        data.extend_from_slice(&mvhd.current_time.to_be_bytes());
        data.extend_from_slice(&mvhd.next_track_id.to_be_bytes());

        data
    }
}

mod parser {
    use winnow::{
        binary::{be_i32, be_u32, be_u64, u8},
        combinator::{opt, seq, trace},
        error::StrContext,
        ModalResult, Parser,
    };

    use super::MovieHeaderAtom;
    use crate::atom::util::parser::{
        be_u32_as_u64, fixed_array, fixed_point_16x16, fixed_point_8x8, flags3, version_0_or_1,
        Stream,
    };

    pub fn parse_mvhd_data(input: &mut Stream<'_>) -> ModalResult<MovieHeaderAtom> {
        let be_u32_or_u64 = |version: u8| {
            let be_u64_type_fix =
                |input: &mut Stream<'_>| -> ModalResult<u64> { be_u64.parse_next(input) };
            match version {
                0 => be_u32_as_u64,
                1 => be_u64_type_fix,
                _ => unreachable!(),
            }
        };

        trace(
            "mvhd",
            seq!(MovieHeaderAtom {
                version: version_0_or_1,
                flags: flags3,
                creation_time: be_u32_or_u64(version).context(StrContext::Label("creation_time")),
                modification_time: be_u32_or_u64(version)
                    .context(StrContext::Label("modification_time")),
                timescale: be_u32.context(StrContext::Label("timescale")),
                duration: be_u32_or_u64(version).context(StrContext::Label("duration")),
                rate: fixed_point_16x16.context(StrContext::Label("rate")),
                volume: fixed_point_8x8.context(StrContext::Label("volume")),
                reserved: fixed_array(u8).context(StrContext::Label("reserved")),
                matrix: opt(fixed_array(be_i32)).context(StrContext::Label("matrix")),
                preview_time: be_u32.context(StrContext::Label("preview_time")),
                preview_duration: be_u32.context(StrContext::Label("preview_duration")),
                poster_time: be_u32.context(StrContext::Label("poster_time")),
                selection_time: be_u32.context(StrContext::Label("selection_time")),
                selection_duration: be_u32.context(StrContext::Label("selection_duration")),
                current_time: be_u32.context(StrContext::Label("current_time")),
                next_track_id: be_u32.context(StrContext::Label("next_track_id")),
            }),
        )
        .parse_next(input)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::atom::test_utils::test_atom_roundtrip;

    /// Test round-trip for all available mvhd test data files
    #[test]
    fn test_mvhd_roundtrip() {
        test_atom_roundtrip::<MovieHeaderAtom>(MVHD);
    }
}