dvb_si/descriptors/
registration.rs

1//! Registration Descriptor — ISO/IEC 13818-1 §2.6.13 (tag 0x05).
2//!
3//! Identifies the registration of a stream or program via a 4-byte
4//! `format_identifier`. Optionally followed by additional identification
5//! information.
6
7use super::descriptor_body;
8use crate::error::{Error, Result};
9use dvb_common::{Parse, Serialize};
10
11/// Descriptor tag for registration_descriptor.
12pub const TAG: u8 = 0x05;
13const HEADER_LEN: usize = 2;
14const FORMAT_IDENTIFIER_LEN: usize = 4;
15
16/// Registration Descriptor.
17///
18/// The `format_identifier` is a 4-byte code registered with a standards body
19/// (e.g. SMPTE, ATSC) that identifies the coding format of the associated
20/// stream. Any bytes beyond the 4-byte identifier are treated as opaque
21/// additional identification info.
22#[derive(Debug, Clone, PartialEq, Eq)]
23#[cfg_attr(feature = "serde", derive(serde::Serialize))]
24#[cfg_attr(feature = "yoke", derive(yoke::Yokeable))]
25pub struct RegistrationDescriptor<'a> {
26    /// 4-byte format identifier (e.g. b"AC-3", b"HDMV", b"dtsx").
27    pub format_identifier: [u8; FORMAT_IDENTIFIER_LEN],
28    /// Optional additional identification bytes following the format identifier.
29    pub additional_identification_info: &'a [u8],
30}
31
32impl<'a> Parse<'a> for RegistrationDescriptor<'a> {
33    type Error = crate::error::Error;
34
35    fn parse(bytes: &'a [u8]) -> Result<Self> {
36        let body = descriptor_body(
37            bytes,
38            TAG,
39            "RegistrationDescriptor",
40            "unexpected tag for registration_descriptor",
41        )?;
42        if body.len() < FORMAT_IDENTIFIER_LEN {
43            return Err(Error::InvalidDescriptor {
44                tag: TAG,
45                reason: "registration_descriptor length too short for format_identifier",
46            });
47        }
48        let mut format_identifier = [0u8; FORMAT_IDENTIFIER_LEN];
49        format_identifier.copy_from_slice(&body[..FORMAT_IDENTIFIER_LEN]);
50        let additional_identification_info = &body[FORMAT_IDENTIFIER_LEN..];
51        Ok(Self {
52            format_identifier,
53            additional_identification_info,
54        })
55    }
56}
57
58impl Serialize for RegistrationDescriptor<'_> {
59    type Error = crate::error::Error;
60
61    fn serialized_len(&self) -> usize {
62        HEADER_LEN + FORMAT_IDENTIFIER_LEN + self.additional_identification_info.len()
63    }
64
65    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
66        let len = self.serialized_len();
67        if buf.len() < len {
68            return Err(Error::OutputBufferTooSmall {
69                need: len,
70                have: buf.len(),
71            });
72        }
73        buf[0] = TAG;
74        buf[1] = (len - HEADER_LEN) as u8;
75        buf[HEADER_LEN..HEADER_LEN + FORMAT_IDENTIFIER_LEN]
76            .copy_from_slice(&self.format_identifier);
77        buf[HEADER_LEN + FORMAT_IDENTIFIER_LEN..len]
78            .copy_from_slice(self.additional_identification_info);
79        Ok(len)
80    }
81}
82impl<'a> crate::traits::DescriptorDef<'a> for RegistrationDescriptor<'a> {
83    const TAG: u8 = TAG;
84    const NAME: &'static str = "REGISTRATION";
85}
86
87#[cfg(test)]
88mod tests {
89    use super::*;
90
91    #[test]
92    fn parse_format_identifier_only() {
93        let bytes = [TAG, 4, b'A', b'C', b'-', b'3'];
94        let d = RegistrationDescriptor::parse(&bytes).unwrap();
95        assert_eq!(&d.format_identifier, b"AC-3");
96        assert!(d.additional_identification_info.is_empty());
97    }
98
99    #[test]
100    fn parse_with_additional_info() {
101        let bytes = [TAG, 6, b'H', b'D', b'M', b'V', 0x01, 0x02];
102        let d = RegistrationDescriptor::parse(&bytes).unwrap();
103        assert_eq!(&d.format_identifier, b"HDMV");
104        assert_eq!(d.additional_identification_info, &[0x01, 0x02]);
105    }
106
107    #[test]
108    fn parse_rejects_wrong_tag() {
109        let err = RegistrationDescriptor::parse(&[0x06, 4, 0, 0, 0, 0]).unwrap_err();
110        assert!(matches!(err, Error::InvalidDescriptor { tag: 0x06, .. }));
111    }
112
113    #[test]
114    fn parse_rejects_short_header() {
115        let err = RegistrationDescriptor::parse(&[TAG]).unwrap_err();
116        assert!(matches!(err, Error::BufferTooShort { .. }));
117    }
118
119    #[test]
120    fn parse_rejects_length_too_short_for_format_id() {
121        let bytes = [TAG, 3, 0, 0, 0];
122        let err = RegistrationDescriptor::parse(&bytes).unwrap_err();
123        assert!(matches!(err, Error::InvalidDescriptor { tag: TAG, .. }));
124    }
125
126    #[test]
127    fn parse_rejects_length_overflow() {
128        let bytes = [TAG, 10, 0, 0, 0, 0];
129        let err = RegistrationDescriptor::parse(&bytes).unwrap_err();
130        assert!(matches!(err, Error::BufferTooShort { .. }));
131    }
132
133    #[test]
134    fn serialize_round_trip() {
135        let d = RegistrationDescriptor {
136            format_identifier: *b"dtsx",
137            additional_identification_info: &[0xAA, 0xBB],
138        };
139        let mut buf = vec![0u8; d.serialized_len()];
140        d.serialize_into(&mut buf).unwrap();
141        let reparsed = RegistrationDescriptor::parse(&buf).unwrap();
142        assert_eq!(d, reparsed);
143    }
144
145    #[test]
146    fn serialize_rejects_small_buffer() {
147        let d = RegistrationDescriptor {
148            format_identifier: *b"AC-3",
149            additional_identification_info: &[],
150        };
151        let mut tiny = vec![0u8; 3];
152        let err = d.serialize_into(&mut tiny).unwrap_err();
153        assert!(matches!(err, Error::OutputBufferTooSmall { .. }));
154    }
155
156    #[test]
157    fn descriptor_length_matches_payload() {
158        let d = RegistrationDescriptor {
159            format_identifier: *b"AC-3",
160            additional_identification_info: &[0x01],
161        };
162        assert_eq!(d.serialized_len() - 2, 5);
163    }
164}
dvb_si/descriptors/registration.rs

dvb_si/descriptors/
registration.rs
