mp4ameta 0.13.0

A library for reading and writing iTunes style MPEG-4 audio metadata.
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

use super::*;

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct Gmhd {
    pub state: State,
    pub gmin: Option<Gmin>,
    pub text: Option<Text>,
}

impl Atom for Gmhd {
    const FOURCC: Fourcc = BASE_MEDIA_INFORMATION_HEADER;
}

impl ParseAtom for Gmhd {
    fn parse_atom(
        reader: &mut (impl Read + Seek),
        cfg: &ParseConfig<'_>,
        size: Size,
    ) -> crate::Result<Self> {
        let bounds = find_bounds(reader, size)?;
        let mut gmhd = Self {
            state: State::Existing(bounds),
            ..Default::default()
        };
        let mut parsed_bytes = 0;

        while parsed_bytes < size.content_len() {
            let remaining_bytes = size.content_len() - parsed_bytes;
            let head = head::parse(reader, remaining_bytes)?;

            match head.fourcc() {
                BASE_MEDIA_INFORMATION => gmhd.gmin = Some(Gmin::parse(reader, cfg, head.size())?),
                TEXT_MEDIA => gmhd.text = Some(Text::parse(reader, cfg, head.size())?),
                _ => reader.skip(head.content_len() as i64)?,
            }

            parsed_bytes += head.len();
        }

        Ok(gmhd)
    }
}

impl AtomSize for Gmhd {
    fn size(&self) -> Size {
        let content_len = self.gmin.len_or_zero() + self.text.len_or_zero();
        Size::from(content_len)
    }
}

impl WriteAtom for Gmhd {
    fn write_atom(&self, writer: &mut impl Write, changes: &[Change<'_>]) -> crate::Result<()> {
        self.write_head(writer)?;

        if let Some(a) = &self.gmin {
            a.write(writer, changes)?;
        }
        if let Some(a) = &self.text {
            a.write(writer, changes)?;
        }
        Ok(())
    }
}

impl SimpleCollectChanges for Gmhd {
    fn state(&self) -> &State {
        &self.state
    }

    fn existing<'a>(
        &'a self,
        level: u8,
        bounds: &'a AtomBounds,
        changes: &mut Vec<Change<'a>>,
    ) -> i64 {
        self.gmin.collect_changes(bounds.end(), level, changes)
            + self.text.collect_changes(bounds.end(), level, changes)
    }

    fn atom_ref(&self) -> AtomRef<'_> {
        AtomRef::Gmhd(self)
    }
}