dvb_si/tables/
eit.rs

1//! Event Information Table — ETSI EN 300 468 §5.2.4.
2//!
3//! EIT carries programme event metadata. Four variants distinguished by
4//! table_id:
5//! - `0x4E` — Present/Following for the actual TS
6//! - `0x4F` — Present/Following for another TS
7//! - `0x50..=0x5F` — Schedule sub-tables for the actual TS
8//! - `0x60..=0x6F` — Schedule sub-tables for another TS
9
10use crate::descriptors::DescriptorLoop;
11use crate::error::{Error, Result};
12use crate::traits::Table;
13use dvb_common::{Parse, Serialize};
14
15/// table_id for present/following on the actual TS.
16pub const TABLE_ID_PF_ACTUAL: u8 = 0x4E;
17/// table_id for present/following on other TSes.
18pub const TABLE_ID_PF_OTHER: u8 = 0x4F;
19/// First table_id in the schedule range for the actual TS.
20pub const TABLE_ID_SCHEDULE_ACTUAL_FIRST: u8 = 0x50;
21/// Last table_id in the schedule range for the actual TS (inclusive).
22pub const TABLE_ID_SCHEDULE_ACTUAL_LAST: u8 = 0x5F;
23/// First table_id in the schedule range for other TSes.
24pub const TABLE_ID_SCHEDULE_OTHER_FIRST: u8 = 0x60;
25/// Last table_id in the schedule range for other TSes (inclusive).
26pub const TABLE_ID_SCHEDULE_OTHER_LAST: u8 = 0x6F;
27/// Well-known PID on which EIT is carried.
28pub const PID: u16 = 0x0012;
29
30const MIN_HEADER_LEN: usize = 3;
31const EXTENSION_HEADER_LEN: usize = 5;
32/// transport_stream_id(2) + original_network_id(2) + segment_last_section_number(1)
33/// + last_table_id(1) = 6 bytes between the section header and the first event.
34const POST_EXTENSION_LEN: usize = 6;
35const CRC_LEN: usize = 4;
36const EVENT_HEADER_LEN: usize = 12;
37
38/// EIT variant distinguished by table_id range.
39#[derive(Debug, Clone, Copy, PartialEq, Eq)]
40#[cfg_attr(feature = "serde", derive(serde::Serialize))]
41pub enum EitKind {
42    /// Present/Following, actual TS.
43    PresentFollowingActual,
44    /// Present/Following, other TS.
45    PresentFollowingOther,
46    /// Schedule, actual TS — table_id `0x50..=0x5F`.
47    ScheduleActual,
48    /// Schedule, other TS — table_id `0x60..=0x6F`.
49    ScheduleOther,
50}
51
52impl EitKind {
53    /// Classify a table_id byte into a kind, if recognised.
54    #[must_use]
55    pub fn from_table_id(table_id: u8) -> Option<Self> {
56        match table_id {
57            TABLE_ID_PF_ACTUAL => Some(Self::PresentFollowingActual),
58            TABLE_ID_PF_OTHER => Some(Self::PresentFollowingOther),
59            TABLE_ID_SCHEDULE_ACTUAL_FIRST..=TABLE_ID_SCHEDULE_ACTUAL_LAST => {
60                Some(Self::ScheduleActual)
61            }
62            TABLE_ID_SCHEDULE_OTHER_FIRST..=TABLE_ID_SCHEDULE_OTHER_LAST => {
63                Some(Self::ScheduleOther)
64            }
65            _ => None,
66        }
67    }
68}
69
70/// One event in the EIT.
71#[derive(Debug, Clone, PartialEq, Eq)]
72#[cfg_attr(feature = "serde", derive(serde::Serialize))]
73pub struct EitEvent<'a> {
74    /// 16-bit event_id.
75    pub event_id: u16,
76    /// 40-bit start_time: 16-bit MJD followed by 24-bit BCD UTC (HHMMSS).
77    pub start_time_raw: [u8; 5],
78    /// 24-bit BCD duration HHMMSS.
79    pub duration_raw: [u8; 3],
80    /// 3-bit running_status.
81    pub running_status: u8,
82    /// free_CA_mode flag.
83    pub free_ca_mode: bool,
84    /// Descriptor loop for this event. Serializes as the typed descriptor
85    /// sequence; `.raw()` yields the wire bytes.
86    pub descriptors: DescriptorLoop<'a>,
87}
88
89/// Event Information Table.
90#[derive(Debug, Clone, PartialEq, Eq)]
91#[cfg_attr(feature = "serde", derive(serde::Serialize))]
92pub struct Eit<'a> {
93    /// Variant based on table_id.
94    pub kind: EitKind,
95    /// Raw table_id byte as parsed (for schedule sub-tables, identifies the slot).
96    pub table_id: u8,
97    /// service_id the events belong to (table_id_extension).
98    pub service_id: u16,
99    /// 5-bit version_number.
100    pub version_number: u8,
101    /// current_next_indicator bit.
102    pub current_next_indicator: bool,
103    /// section_number.
104    pub section_number: u8,
105    /// last_section_number.
106    pub last_section_number: u8,
107    /// transport_stream_id the events are carried on.
108    pub transport_stream_id: u16,
109    /// original_network_id.
110    pub original_network_id: u16,
111    /// segment_last_section_number.
112    pub segment_last_section_number: u8,
113    /// last_table_id (for schedule sub-table grouping).
114    pub last_table_id: u8,
115    /// Events in wire order.
116    pub events: Vec<EitEvent<'a>>,
117}
118
119impl<'a> Parse<'a> for Eit<'a> {
120    type Error = crate::error::Error;
121    fn parse(bytes: &'a [u8]) -> Result<Self> {
122        let min_len = MIN_HEADER_LEN + EXTENSION_HEADER_LEN + POST_EXTENSION_LEN + CRC_LEN;
123        if bytes.len() < min_len {
124            return Err(Error::BufferTooShort {
125                need: min_len,
126                have: bytes.len(),
127                what: "Eit",
128            });
129        }
130
131        let table_id = bytes[0];
132        let kind = EitKind::from_table_id(table_id).ok_or(Error::UnexpectedTableId {
133            table_id,
134            what: "Eit",
135            expected: &[
136                TABLE_ID_PF_ACTUAL,
137                TABLE_ID_PF_OTHER,
138                TABLE_ID_SCHEDULE_ACTUAL_FIRST,
139                TABLE_ID_SCHEDULE_OTHER_FIRST,
140            ],
141        })?;
142
143        let section_length = ((bytes[1] & 0x0F) as u16) << 8 | bytes[2] as u16;
144        let total = MIN_HEADER_LEN + section_length as usize;
145        if bytes.len() < total {
146            return Err(Error::SectionLengthOverflow {
147                declared: section_length as usize,
148                available: bytes.len() - MIN_HEADER_LEN,
149            });
150        }
151
152        let service_id = u16::from_be_bytes([bytes[3], bytes[4]]);
153        let version_number = (bytes[5] >> 1) & 0x1F;
154        let current_next_indicator = (bytes[5] & 0x01) != 0;
155        let section_number = bytes[6];
156        let last_section_number = bytes[7];
157
158        let transport_stream_id = u16::from_be_bytes([bytes[8], bytes[9]]);
159        let original_network_id = u16::from_be_bytes([bytes[10], bytes[11]]);
160        let segment_last_section_number = bytes[12];
161        let last_table_id = bytes[13];
162
163        let events_start = MIN_HEADER_LEN + EXTENSION_HEADER_LEN + POST_EXTENSION_LEN;
164        let events_end = total - CRC_LEN;
165        let mut events = Vec::new();
166        let mut pos = events_start;
167        while pos + EVENT_HEADER_LEN <= events_end {
168            let event_id = u16::from_be_bytes([bytes[pos], bytes[pos + 1]]);
169            let start_time_raw = [
170                bytes[pos + 2],
171                bytes[pos + 3],
172                bytes[pos + 4],
173                bytes[pos + 5],
174                bytes[pos + 6],
175            ];
176            let duration_raw = [bytes[pos + 7], bytes[pos + 8], bytes[pos + 9]];
177            let status_and_len_hi = bytes[pos + 10];
178            let running_status = (status_and_len_hi >> 5) & 0x07;
179            let free_ca_mode = (status_and_len_hi & 0x10) != 0;
180            let descriptors_loop_length =
181                (((status_and_len_hi & 0x0F) as usize) << 8) | bytes[pos + 11] as usize;
182            let desc_start = pos + EVENT_HEADER_LEN;
183            let desc_end = desc_start + descriptors_loop_length;
184            if desc_end > events_end {
185                return Err(Error::SectionLengthOverflow {
186                    declared: descriptors_loop_length,
187                    available: events_end - desc_start,
188                });
189            }
190            events.push(EitEvent {
191                event_id,
192                start_time_raw,
193                duration_raw,
194                running_status,
195                free_ca_mode,
196                descriptors: DescriptorLoop::new(&bytes[desc_start..desc_end]),
197            });
198            pos = desc_end;
199        }
200
201        Ok(Eit {
202            kind,
203            table_id,
204            service_id,
205            version_number,
206            current_next_indicator,
207            section_number,
208            last_section_number,
209            transport_stream_id,
210            original_network_id,
211            segment_last_section_number,
212            last_table_id,
213            events,
214        })
215    }
216}
217
218impl Serialize for Eit<'_> {
219    type Error = crate::error::Error;
220    fn serialized_len(&self) -> usize {
221        let ev_bytes: usize = self
222            .events
223            .iter()
224            .map(|e| EVENT_HEADER_LEN + e.descriptors.len())
225            .sum();
226        MIN_HEADER_LEN + EXTENSION_HEADER_LEN + POST_EXTENSION_LEN + ev_bytes + CRC_LEN
227    }
228
229    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
230        let len = self.serialized_len();
231        if buf.len() < len {
232            return Err(Error::OutputBufferTooSmall {
233                need: len,
234                have: buf.len(),
235            });
236        }
237        let section_length: u16 = (len - MIN_HEADER_LEN) as u16;
238        buf[0] = self.table_id;
239        buf[1] = 0xB0 | ((section_length >> 8) as u8 & 0x0F);
240        buf[2] = (section_length & 0xFF) as u8;
241        buf[3..5].copy_from_slice(&self.service_id.to_be_bytes());
242        buf[5] = 0xC0 | ((self.version_number & 0x1F) << 1) | u8::from(self.current_next_indicator);
243        buf[6] = self.section_number;
244        buf[7] = self.last_section_number;
245        buf[8..10].copy_from_slice(&self.transport_stream_id.to_be_bytes());
246        buf[10..12].copy_from_slice(&self.original_network_id.to_be_bytes());
247        buf[12] = self.segment_last_section_number;
248        buf[13] = self.last_table_id;
249
250        let mut pos = MIN_HEADER_LEN + EXTENSION_HEADER_LEN + POST_EXTENSION_LEN;
251        for ev in &self.events {
252            buf[pos..pos + 2].copy_from_slice(&ev.event_id.to_be_bytes());
253            buf[pos + 2..pos + 7].copy_from_slice(&ev.start_time_raw);
254            buf[pos + 7..pos + 10].copy_from_slice(&ev.duration_raw);
255            let dll = ev.descriptors.len() as u16;
256            buf[pos + 10] = ((ev.running_status & 0x07) << 5)
257                | (u8::from(ev.free_ca_mode) << 4)
258                | ((dll >> 8) as u8 & 0x0F);
259            buf[pos + 11] = (dll & 0xFF) as u8;
260            let desc_start = pos + EVENT_HEADER_LEN;
261            buf[desc_start..desc_start + ev.descriptors.len()]
262                .copy_from_slice(ev.descriptors.raw());
263            pos = desc_start + ev.descriptors.len();
264        }
265
266        let crc_pos = len - CRC_LEN;
267        let crc = dvb_common::crc32_mpeg2::compute(&buf[..crc_pos]);
268        buf[crc_pos..len].copy_from_slice(&crc.to_be_bytes());
269        Ok(len)
270    }
271}
272
273impl<'a> Table<'a> for Eit<'a> {
274    const TABLE_ID: u8 = TABLE_ID_PF_ACTUAL;
275    const PID: u16 = PID;
276}
277
278impl<'a> crate::traits::TableDef<'a> for Eit<'a> {
279    const TABLE_ID_RANGES: &'static [(u8, u8)] =
280        &[(TABLE_ID_PF_ACTUAL, TABLE_ID_SCHEDULE_OTHER_LAST)];
281    const NAME: &'static str = "EVENT_INFORMATION";
282}
283
284#[cfg(feature = "chrono")]
285impl EitEvent<'_> {
286    /// Decode `start_time_raw` (16-bit MJD + 24-bit BCD UTC) to a UTC datetime.
287    /// Returns `None` if the BCD nibbles are out of range.
288    ///
289    /// MJD→calendar conversion per ETSI EN 300 468 Annex C.
290    #[must_use]
291    pub fn start_time(&self) -> Option<chrono::DateTime<chrono::Utc>> {
292        use chrono::{NaiveDate, NaiveDateTime, TimeZone};
293        let mjd = u16::from_be_bytes([self.start_time_raw[0], self.start_time_raw[1]]);
294        let (y, m, d) = mjd_to_ymd(mjd);
295        let h = bcd_byte(self.start_time_raw[2])?;
296        let mi = bcd_byte(self.start_time_raw[3])?;
297        let s = bcd_byte(self.start_time_raw[4])?;
298        let date = NaiveDate::from_ymd_opt(y, m, d)?;
299        let time = chrono::NaiveTime::from_hms_opt(u32::from(h), u32::from(mi), u32::from(s))?;
300        let naive = NaiveDateTime::new(date, time);
301        chrono::Utc.from_local_datetime(&naive).single()
302    }
303}
304
305#[cfg(feature = "chrono")]
306fn bcd_byte(b: u8) -> Option<u8> {
307    let hi = b >> 4;
308    let lo = b & 0x0F;
309    if hi > 9 || lo > 9 {
310        return None;
311    }
312    Some(hi * 10 + lo)
313}
314
315#[cfg(feature = "chrono")]
316fn mjd_to_ymd(mjd: u16) -> (i32, u32, u32) {
317    // ETSI EN 300 468 Annex C: Y', M', K, Y, M, D via the Zeller-like formula.
318    let mjd = i64::from(mjd);
319    let y_prime = ((mjd as f64 - 15_078.2) / 365.25) as i64;
320    let m_prime = ((mjd as f64 - 14_956.1 - (y_prime as f64 * 365.25).floor()) / 30.6001) as i64;
321    let d = mjd
322        - 14_956
323        - (y_prime as f64 * 365.25).floor() as i64
324        - (m_prime as f64 * 30.6001).floor() as i64;
325    let k = if m_prime == 14 || m_prime == 15 { 1 } else { 0 };
326    let y = y_prime + k + 1900;
327    let m = m_prime - 1 - k * 12;
328    (y as i32, m as u32, d as u32)
329}
330
331#[cfg(test)]
332mod tests {
333    use super::*;
334
335    type TestEvent = (u16, [u8; 5], [u8; 3], u8, bool, Vec<u8>);
336
337    fn build_eit(
338        table_id: u8,
339        service_id: u16,
340        version: u8,
341        tsid: u16,
342        onid: u16,
343        events: &[TestEvent],
344    ) -> Vec<u8> {
345        let ev_bytes: usize = events
346            .iter()
347            .map(|(_, _, _, _, _, d)| EVENT_HEADER_LEN + d.len())
348            .sum();
349        let section_length: u16 =
350            (EXTENSION_HEADER_LEN + POST_EXTENSION_LEN + ev_bytes + CRC_LEN) as u16;
351        let mut v = Vec::new();
352        v.push(table_id);
353        v.push(0xB0 | ((section_length >> 8) as u8 & 0x0F));
354        v.push((section_length & 0xFF) as u8);
355        v.extend_from_slice(&service_id.to_be_bytes());
356        v.push(0xC0 | ((version & 0x1F) << 1) | 0x01);
357        v.push(0);
358        v.push(0);
359        v.extend_from_slice(&tsid.to_be_bytes());
360        v.extend_from_slice(&onid.to_be_bytes());
361        v.push(0);
362        v.push(table_id);
363        for (eid, start, dur, rs, fca, desc) in events {
364            v.extend_from_slice(&eid.to_be_bytes());
365            v.extend_from_slice(start);
366            v.extend_from_slice(dur);
367            let dll = desc.len() as u16;
368            v.push(((*rs & 0x07) << 5) | (u8::from(*fca) << 4) | ((dll >> 8) as u8 & 0x0F));
369            v.push((dll & 0xFF) as u8);
370            v.extend_from_slice(desc);
371        }
372        v.extend_from_slice(&[0, 0, 0, 0]);
373        v
374    }
375
376    #[test]
377    fn parse_pf_actual_and_other_map_to_correct_kind() {
378        for (tid, expected) in [
379            (TABLE_ID_PF_ACTUAL, EitKind::PresentFollowingActual),
380            (TABLE_ID_PF_OTHER, EitKind::PresentFollowingOther),
381        ] {
382            let bytes = build_eit(tid, 1, 0, 0x20, 0x30, &[]);
383            assert_eq!(Eit::parse(&bytes).unwrap().kind, expected);
384        }
385    }
386
387    #[test]
388    fn schedule_tables_0x50_through_0x5f_all_decode_as_schedule_actual() {
389        for tid in TABLE_ID_SCHEDULE_ACTUAL_FIRST..=TABLE_ID_SCHEDULE_ACTUAL_LAST {
390            let bytes = build_eit(tid, 1, 0, 0x20, 0x30, &[]);
391            assert_eq!(Eit::parse(&bytes).unwrap().kind, EitKind::ScheduleActual);
392        }
393    }
394
395    #[test]
396    fn schedule_tables_0x60_through_0x6f_all_decode_as_schedule_other() {
397        for tid in TABLE_ID_SCHEDULE_OTHER_FIRST..=TABLE_ID_SCHEDULE_OTHER_LAST {
398            let bytes = build_eit(tid, 1, 0, 0x20, 0x30, &[]);
399            assert_eq!(Eit::parse(&bytes).unwrap().kind, EitKind::ScheduleOther);
400        }
401    }
402
403    #[test]
404    fn event_loop_with_descriptor_bytes_preserved() {
405        let desc = vec![0x4D, 0x05, 0x01, 0x02, 0x03, 0x04, 0x05];
406        let bytes = build_eit(
407            TABLE_ID_PF_ACTUAL,
408            1,
409            0,
410            0x20,
411            0x30,
412            &[(
413                42,
414                [0xDF, 0xA1, 0x12, 0x34, 0x56],
415                [0x00, 0x30, 0x00],
416                4,
417                false,
418                desc.clone(),
419            )],
420        );
421        let eit = Eit::parse(&bytes).unwrap();
422        assert_eq!(eit.events.len(), 1);
423        assert_eq!(eit.events[0].event_id, 42);
424        assert_eq!(eit.events[0].descriptors.raw(), &desc[..]);
425    }
426
427    #[test]
428    fn running_status_extracted() {
429        let bytes = build_eit(
430            TABLE_ID_PF_ACTUAL,
431            1,
432            0,
433            0x20,
434            0x30,
435            &[(1, [0; 5], [0; 3], 2, false, vec![])],
436        );
437        assert_eq!(Eit::parse(&bytes).unwrap().events[0].running_status, 2);
438    }
439
440    #[test]
441    fn free_ca_mode_flag_extracted() {
442        let bytes = build_eit(
443            TABLE_ID_PF_ACTUAL,
444            1,
445            0,
446            0x20,
447            0x30,
448            &[(1, [0; 5], [0; 3], 0, true, vec![])],
449        );
450        assert!(Eit::parse(&bytes).unwrap().events[0].free_ca_mode);
451    }
452
453    #[test]
454    fn serialize_round_trip_preserves_all_events() {
455        let desc1: [u8; 2] = [0x54, 0x00];
456        let eit = Eit {
457            kind: EitKind::PresentFollowingActual,
458            table_id: TABLE_ID_PF_ACTUAL,
459            service_id: 0x0100,
460            version_number: 3,
461            current_next_indicator: true,
462            section_number: 0,
463            last_section_number: 0,
464            transport_stream_id: 0x1234,
465            original_network_id: 0x0020,
466            segment_last_section_number: 0,
467            last_table_id: TABLE_ID_PF_ACTUAL,
468            events: vec![
469                EitEvent {
470                    event_id: 1,
471                    start_time_raw: [0xDF, 0xA1, 0x12, 0x34, 0x56],
472                    duration_raw: [0x00, 0x30, 0x00],
473                    running_status: 4,
474                    free_ca_mode: false,
475                    descriptors: DescriptorLoop::new(&desc1),
476                },
477                EitEvent {
478                    event_id: 2,
479                    start_time_raw: [0xDF, 0xA1, 0x13, 0x00, 0x00],
480                    duration_raw: [0x01, 0x00, 0x00],
481                    running_status: 1,
482                    free_ca_mode: true,
483                    descriptors: DescriptorLoop::new(&[]),
484                },
485            ],
486        };
487        let mut buf = vec![0u8; eit.serialized_len()];
488        eit.serialize_into(&mut buf).unwrap();
489        let re = Eit::parse(&buf).unwrap();
490        assert_eq!(eit, re);
491    }
492
493    #[test]
494    fn zero_events_is_valid() {
495        let bytes = build_eit(TABLE_ID_PF_ACTUAL, 1, 0, 0x20, 0x30, &[]);
496        let eit = Eit::parse(&bytes).unwrap();
497        assert_eq!(eit.events.len(), 0);
498    }
499
500    #[test]
501    #[cfg(feature = "chrono")]
502    fn event_start_time_decodes_to_utc_datetime() {
503        // MJD 59945 is 2023-01-01 per ETSI EN 300 468 Annex C; BCD time 12:34:56.
504        let mjd: u16 = 59945;
505        let ev = EitEvent {
506            event_id: 1,
507            start_time_raw: [(mjd >> 8) as u8, (mjd & 0xFF) as u8, 0x12, 0x34, 0x56],
508            duration_raw: [0, 0, 0],
509            running_status: 0,
510            free_ca_mode: false,
511            descriptors: DescriptorLoop::new(&[]),
512        };
513        let dt = ev.start_time().unwrap();
514        use chrono::Datelike;
515        assert_eq!(dt.year(), 2023);
516        assert_eq!(dt.month(), 1);
517        assert_eq!(dt.day(), 1);
518        use chrono::Timelike;
519        assert_eq!(dt.hour(), 12);
520        assert_eq!(dt.minute(), 34);
521        assert_eq!(dt.second(), 56);
522    }
523}
dvb_si/tables/eit.rs

dvb_si/tables/
eit.rs
