matthew
398430af09
MKV: cluster boundaries now require a video keyframe in addition to the 5s minimum, so every cluster has a CuePoint at its start. Pre-first- keyframe frames are dropped. Adds a SeekHead at Segment start with fixed-width back-patched SeekPositions for Info/Tracks/Chapters/Cues. Before this change a 2h26m UHD rip had 52 CuePoints across ~1750 clusters and a 16.5-minute gap between adjacent seek entries; players seeking inside that gap had to scan from the prior cue. After, one CuePoint per cluster. TS (tsmux production path + m2ts_mux): PesFrame.keyframe is plumbed end-to-end. Codec-private parameter sets are prepended on the first keyframe (not the first frame); non-key video before any keyframe is dropped. The first TS packet of a keyframe video PES carries an adaptation field with random_access_indicator=1. m2ts_mux previously hardcoded RAI=1 on every PCR packet; that is now gated on the current PES being a keyframe video PES, combining correctly with PCR when both land on the same packet. Adds 17 tests covering keyframe alignment, cue count/position/timing, SeekHead correctness, RAI set/clear, codec_private gating, non-key drop, and PCR+RAI combination.
829 lines
32 KiB
Rust
829 lines
32 KiB
Rust
//! Standard MPEG-TS (188-byte packets) muxer — sequential-only.
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//!
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//! Distinct from `super::tsmux::TsMuxer` (BD-TS with 192-byte packets
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//! and the 4-byte TP_extra_header). This muxer emits the IETF / ISO/IEC
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//! 13818-1 wire format that ffmpeg, VLC, and `m2tsindex` consume
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//! out of the box. Use it for plain `.ts` / `.m2ts` files over a
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//! [`SequentialSink`](crate::io::sink::SequentialSink), and for
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//! MPEG-TS-over-UDP via [`UdpSocketSink`](crate::io::sink::UdpSocketSink).
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//!
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//! ## Wire format
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//!
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//! Every output packet is exactly 188 bytes:
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//!
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//! ```text
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//! sync_byte:8 = 0x47
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//! transport_error_indicator:1 = 0
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//! payload_unit_start_indicator:1
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//! transport_priority:1 = 0
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//! PID:13
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//! transport_scrambling_control:2 = 0
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//! adaptation_field_control:2
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//! continuity_counter:4
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//! [adaptation field, if signalled]
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//! [payload, if signalled]
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//! ```
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//!
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//! ## Wiring
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//!
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//! Single program (PMT PID `0x1000`, program number `1`):
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//! - PAT on PID `0x0000`
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//! - PMT on PID `0x1000`
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//! - Video (HEVC, stream_type `0x24`) on PID `0x0100`
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//! - First audio (AC3, stream_type `0x81`) on PID `0x0101`
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//! (or TrueHD, stream_type `0x83`, if hinted)
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//!
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//! ## Scope vs. full TS
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//!
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//! This is a deliberately minimal viable muxer:
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//! - One program, one video track, optionally one audio track.
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//! - PAT + PMT re-emitted every `PSI_INTERVAL_PACKETS` packets so a
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//! mid-stream receiver can lock on within ~100 ms at typical
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//! UHD bitrates.
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//! - PCR clock derived from video PTS (`pts - PCR_LEAD_90KHZ`),
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//! attached to the video PID's adaptation field every
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//! `PCR_INTERVAL_PACKETS` packets.
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//! - No language / descriptor tags, no SCTE-35 markers, no per-PID
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//! PMT version bumps, no SDT/EIT. Sufficient for "ffmpeg can play
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//! this back", not for full broadcast deployment.
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use std::io::{self, Write};
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mod packet;
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use packet::{Packet, PacketWriter};
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/// PID `0x0000` — PAT, mandated by spec.
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const PID_PAT: u16 = 0x0000;
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/// PID for the single program's PMT. `0x1000` is the conventional
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/// choice; anything outside reserved/null ranges works.
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const PID_PMT: u16 = 0x1000;
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/// PID for the video elementary stream.
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const PID_VIDEO: u16 = 0x0100;
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/// PID for the (optional) first audio elementary stream.
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const PID_AUDIO: u16 = 0x0101;
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/// Null PID — reserved by spec; never used here.
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#[allow(dead_code)]
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const PID_NULL: u16 = 0x1FFF;
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/// Re-emit PAT/PMT every N TS packets. ~250 × 188 B = 47 KB; at
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/// 80 Mb/s UHD that's ~5 ms — well under typical receiver lock budget.
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const PSI_INTERVAL_PACKETS: u64 = 250;
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/// Re-stamp PCR every N TS packets carrying the video PID. Spec MAX
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/// is 100 ms; 40 packets × 188 B at moderate bitrate keeps us under.
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const PCR_INTERVAL_PACKETS: u64 = 40;
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/// PCR lead time — the PCR must precede the PTS of the first byte of
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/// the picture it timestamps. 200 ms in 90 kHz ticks.
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const PCR_LEAD_90KHZ: u64 = 90_000 / 5;
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/// Stream-type codes from ISO/IEC 13818-1 Table 2-29 + later amendments.
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const STREAM_TYPE_HEVC: u8 = 0x24;
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const STREAM_TYPE_AC3: u8 = 0x81;
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const STREAM_TYPE_TRUEHD: u8 = 0x83;
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/// Audio codec hint for [`M2tsMux::new`] / [`M2tsMux::set_audio`]. The
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/// muxer needs to know the codec to pick the right PMT `stream_type`
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/// and the right PES stream_id; it doesn't decode the audio.
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#[derive(Debug, Clone, Copy)]
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pub enum AudioCodec {
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/// AC-3 / E-AC-3, stream_type `0x81`, PES stream_id `0xBD`.
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Ac3,
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/// Dolby TrueHD, stream_type `0x83`, PES stream_id `0xBD`.
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TrueHd,
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}
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impl AudioCodec {
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fn stream_type(self) -> u8 {
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match self {
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AudioCodec::Ac3 => STREAM_TYPE_AC3,
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AudioCodec::TrueHd => STREAM_TYPE_TRUEHD,
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}
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}
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}
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/// Sequential MPEG-TS muxer with one video and optional one audio track.
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pub struct M2tsMux<W: Write> {
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out: PacketWriter<W>,
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/// hvcC parameter set bytes to prepend to the first video PES.
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/// Optional — if the upstream frames already carry inline params,
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/// callers can omit this.
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video_codec_private: Option<Vec<u8>>,
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/// Set on first video frame: have we emitted VPS/SPS/PPS?
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params_written: bool,
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/// Audio codec, if an audio track is configured. `None` = video-only.
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audio: Option<AudioCodec>,
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/// First seen PTS (90 kHz). All subsequent PTS / PCR values are
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/// relative to this so output streams start near t=0 and don't
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/// confuse downstream parsers that don't tolerate huge starting
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/// timestamps.
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base_pts_90k: Option<u64>,
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/// Per-PID continuity counter, 4 bits, monotonically increasing.
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cc_video: u8,
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cc_audio: u8,
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cc_pat: u8,
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cc_pmt: u8,
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/// Total packets written, used to gate PSI / PCR cadence.
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packets_written: u64,
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/// Video packets written since last PCR, used to gate PCR cadence.
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video_packets_since_pcr: u64,
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}
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impl<W: Write> M2tsMux<W> {
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/// Construct a muxer wrapping `writer`. By default audio is
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/// disabled; call [`set_audio`](Self::set_audio) before the first
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/// frame to enable.
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pub fn new(writer: W) -> Self {
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Self {
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out: PacketWriter::new(writer),
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video_codec_private: None,
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params_written: false,
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audio: None,
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base_pts_90k: None,
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cc_video: 0,
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cc_audio: 0,
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cc_pat: 0,
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cc_pmt: 0,
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packets_written: 0,
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video_packets_since_pcr: 0,
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}
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}
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/// Provide the `HEVCDecoderConfigurationRecord` for video so the
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/// muxer prepends VPS/SPS/PPS Annex B NALs at stream start.
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pub fn set_video_codec_private(&mut self, hvcc: Vec<u8>) {
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self.video_codec_private = Some(hvcc);
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}
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/// Enable a single audio track. Must be called before
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/// [`write_audio`](Self::write_audio).
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pub fn set_audio(&mut self, codec: AudioCodec) {
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self.audio = Some(codec);
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}
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/// Write one video PES frame. `data` is either length-prefixed
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/// NALUs (MKV-style) or already Annex B; both are accepted. `keyframe`
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/// drives the random_access_indicator bit on the first packet of this
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/// PES (and gates codec_private NAL prepending — those only attach to
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/// the first keyframe).
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pub fn write_video(&mut self, pts_ns: i64, keyframe: bool, data: &[u8]) -> io::Result<()> {
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let pts_90k = self.base_relative_pts(pts_ns);
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// PCR comes "before" the PTS it timestamps; clamp at 0 for the
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// first frame so we don't underflow.
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let pcr = pts_90k.saturating_sub(PCR_LEAD_90KHZ);
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// Annex-B-ify the frame and prepend VPS/SPS/PPS once, on the
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// FIRST keyframe (not first frame — non-key frames before the
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// first keyframe can't carry params usefully).
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let mut es = Vec::with_capacity(data.len() + 64);
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if keyframe && !self.params_written {
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if let Some(cp) = &self.video_codec_private {
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let payload = hvcc_payload(cp);
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if !payload.is_empty() {
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let params = super::hevc::length_prefixed_to_annex_b(&payload);
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es.extend_from_slice(¶ms);
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}
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}
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self.params_written = true;
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}
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let annex_b = super::hevc::length_prefixed_to_annex_b(data);
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es.extend_from_slice(&annex_b);
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let pes = build_video_pes(pts_90k, &es);
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self.write_pes(PID_VIDEO, &pes, Some(pcr), keyframe)
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}
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/// Write one audio PES frame. Returns `Ok(())` and silently drops
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/// the frame if no audio track was configured — the design assumes
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/// the upstream picks tracks and won't ship audio to a video-only
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/// muxer, but defending against it keeps the API a single shape.
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pub fn write_audio(&mut self, pts_ns: i64, data: &[u8]) -> io::Result<()> {
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if self.audio.is_none() {
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return Ok(());
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}
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let pts_90k = self.base_relative_pts(pts_ns);
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let pes = build_audio_pes(pts_90k, data);
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self.write_pes(PID_AUDIO, &pes, None, false)
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}
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/// Drain the underlying writer. No TS-level trailer is mandatory —
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/// receivers detect end-of-stream from socket close or file EOF.
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pub fn finish(&mut self) -> io::Result<()> {
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self.out.flush()
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}
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/// Convert input PTS (nanoseconds) to 90 kHz ticks rebased on the
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/// first frame's PTS. Saturating at 0 keeps the math friendly when
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/// frames arrive slightly out of decode order.
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fn base_relative_pts(&mut self, pts_ns: i64) -> u64 {
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let raw_90k = if pts_ns > 0 {
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(pts_ns as u64) * 9 / 100_000
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} else {
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0
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};
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let base = *self.base_pts_90k.get_or_insert(raw_90k);
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raw_90k.saturating_sub(base)
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}
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/// Emit one PES payload as a chain of TS packets on `pid`. If `pcr`
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/// is provided the first packet carries an adaptation field with
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/// the PCR. PAT/PMT are re-emitted every `PSI_INTERVAL_PACKETS`.
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///
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/// Packet-size math (TS = 188 bytes, header = 4 bytes):
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/// - 184 B remain after the header for the adaptation-field area
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/// plus the payload area.
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/// - With AF body of `b` bytes and `s` stuffing bytes: AF total =
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/// `1 + b + s` (the leading `1` is the `adaptation_field_length`
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/// byte itself). Payload = `184 - (1 + b + s)`.
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/// - With no AF area at all: payload = `184`.
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///
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/// The fit-the-tail logic on the last packet of the PES uses
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/// stuffing rather than a separate small packet, which is the
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/// standard MPEG-TS convention.
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fn write_pes(
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&mut self,
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pid: u16,
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pes: &[u8],
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pcr: Option<u64>,
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is_keyframe_video: bool,
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) -> io::Result<()> {
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// PSI cadence is enforced per TS packet — interleave a fresh
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// PAT+PMT into the packet stream every PSI_INTERVAL_PACKETS so
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// long single-PES emissions (e.g. one 60 KB video frame) don't
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// starve receivers tuning in mid-stream.
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let mut offset = 0;
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let mut first = true;
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while offset < pes.len() {
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self.maybe_emit_psi()?;
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let attach_pcr = first
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&& (pid == PID_VIDEO)
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&& (pcr.is_some())
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&& (self.packets_written == 0
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|| self.video_packets_since_pcr >= PCR_INTERVAL_PACKETS);
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// RAI rides only the FIRST packet of a keyframe video PES.
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let attach_rai = first && is_keyframe_video && pid == PID_VIDEO;
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let mut af_body: Vec<u8> = if attach_pcr {
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build_pcr_adaptation(pcr.unwrap_or(0))
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} else {
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Vec::new()
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};
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if attach_rai {
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if af_body.is_empty() {
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af_body.push(0x40); // flags: RAI only
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} else {
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af_body[0] |= 0x40; // OR RAI into existing PCR flags
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}
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}
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let remaining = pes.len() - offset;
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// Capacity for payload given AF body and 1-byte AF length.
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// When AF body is empty we can still skip the AF entirely
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// and get the full 184 B; only invoke the AF when we'd
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// otherwise need stuffing.
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let (af_present, payload_len, stuffing): (bool, usize, usize) = if !af_body.is_empty() {
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// AF is mandatory (PCR). 1 byte length + body + stuffing
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// + payload = 184.
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let max_payload = 184 - 1 - af_body.len();
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let p = remaining.min(max_payload);
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let s = max_payload - p;
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(true, p, s)
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} else if remaining >= 184 {
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// Full payload packet — no AF at all.
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(false, 184, 0)
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} else {
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// Last (small) packet — stuff via empty AF.
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// 1 byte length + 0 body + stuffing + payload = 184.
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let max_payload = 183;
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let p = remaining.min(max_payload);
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let s = max_payload - p;
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(true, p, s)
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};
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let cc = self.advance_cc(pid);
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let mut packet = Packet::new();
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packet.set_header(pid, first, true, af_present, cc);
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if af_present {
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packet.append_adaptation(&af_body, stuffing);
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}
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packet.append_payload(&pes[offset..offset + payload_len]);
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debug_assert_eq!(packet.len(), 188, "packet not 188 bytes");
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self.out.write_packet(&packet)?;
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self.packets_written += 1;
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if pid == PID_VIDEO {
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if attach_pcr {
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self.video_packets_since_pcr = 0;
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} else {
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self.video_packets_since_pcr += 1;
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}
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}
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offset += payload_len;
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first = false;
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}
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Ok(())
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}
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fn advance_cc(&mut self, pid: u16) -> u8 {
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let slot = match pid {
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PID_VIDEO => &mut self.cc_video,
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PID_AUDIO => &mut self.cc_audio,
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PID_PAT => &mut self.cc_pat,
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PID_PMT => &mut self.cc_pmt,
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_ => return 0,
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};
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let cc = *slot;
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*slot = (*slot + 1) & 0x0F;
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cc
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}
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fn maybe_emit_psi(&mut self) -> io::Result<()> {
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if self.packets_written == 0 || self.packets_written % PSI_INTERVAL_PACKETS == 0 {
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self.emit_pat()?;
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self.emit_pmt()?;
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}
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Ok(())
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}
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fn emit_pat(&mut self) -> io::Result<()> {
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let payload = build_pat(PID_PMT);
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let cc = self.advance_cc(PID_PAT);
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let mut packet = Packet::new();
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packet.set_header(PID_PAT, true, true, false, cc);
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packet.append_payload(&payload);
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packet.pad_to_188();
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self.out.write_packet(&packet)?;
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self.packets_written += 1;
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Ok(())
|
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}
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||
|
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fn emit_pmt(&mut self) -> io::Result<()> {
|
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let payload = build_pmt(self.audio);
|
||
let cc = self.advance_cc(PID_PMT);
|
||
let mut packet = Packet::new();
|
||
packet.set_header(PID_PMT, true, true, false, cc);
|
||
packet.append_payload(&payload);
|
||
packet.pad_to_188();
|
||
self.out.write_packet(&packet)?;
|
||
self.packets_written += 1;
|
||
Ok(())
|
||
}
|
||
}
|
||
|
||
/// Extract the raw hvcC bytes for handoff to `length_prefixed_to_annex_b`.
|
||
/// hvcC layout: 22-byte fixed header, then `numOfArrays` arrays of
|
||
/// `(nalType, numNalus, [nalLength:u16, NAL bytes]…)`. We convert this
|
||
/// directly to a length-prefixed byte stream (NAL length is u16 in
|
||
/// hvcC; widen to u32 for the standard length-prefixed encoding).
|
||
fn hvcc_payload(hvcc: &[u8]) -> Vec<u8> {
|
||
if hvcc.len() < 23 {
|
||
return Vec::new();
|
||
}
|
||
let num_arrays = hvcc[22] as usize;
|
||
let mut out = Vec::new();
|
||
let mut offset = 23;
|
||
for _ in 0..num_arrays {
|
||
if offset + 3 > hvcc.len() {
|
||
break;
|
||
}
|
||
offset += 1;
|
||
let num_nalus = u16::from_be_bytes([hvcc[offset], hvcc[offset + 1]]) as usize;
|
||
offset += 2;
|
||
for _ in 0..num_nalus {
|
||
if offset + 2 > hvcc.len() {
|
||
break;
|
||
}
|
||
let nal_len = u16::from_be_bytes([hvcc[offset], hvcc[offset + 1]]) as usize;
|
||
offset += 2;
|
||
if offset + nal_len > hvcc.len() {
|
||
break;
|
||
}
|
||
out.extend_from_slice(&(nal_len as u32).to_be_bytes());
|
||
out.extend_from_slice(&hvcc[offset..offset + nal_len]);
|
||
offset += nal_len;
|
||
}
|
||
}
|
||
out
|
||
}
|
||
|
||
/// Build a PES packet for a video access unit.
|
||
fn build_video_pes(pts_90k: u64, es: &[u8]) -> Vec<u8> {
|
||
build_pes_packet(0xE0, pts_90k, es, /* length_in_header */ false)
|
||
}
|
||
|
||
/// Build a PES packet for an audio access unit.
|
||
fn build_audio_pes(pts_90k: u64, es: &[u8]) -> Vec<u8> {
|
||
// Audio PES: length is fillable when it fits in u16. We always
|
||
// write the length so receivers don't have to scan for the next
|
||
// start code.
|
||
build_pes_packet(0xBD, pts_90k, es, /* length_in_header */ true)
|
||
}
|
||
|
||
fn build_pes_packet(stream_id: u8, pts_90k: u64, es: &[u8], length_in_header: bool) -> Vec<u8> {
|
||
let mut out = Vec::with_capacity(es.len() + 14);
|
||
out.extend_from_slice(&[0x00, 0x00, 0x01, stream_id]);
|
||
// PES_packet_length: total bytes after this field. 3 flag bytes + 5
|
||
// PTS bytes + es.len(). Zero means "unbounded" — used for video
|
||
// where PES can exceed u16.
|
||
let pes_len = 8 + es.len();
|
||
if length_in_header && pes_len <= u16::MAX as usize {
|
||
out.extend_from_slice(&(pes_len as u16).to_be_bytes());
|
||
} else {
|
||
out.extend_from_slice(&[0x00, 0x00]);
|
||
}
|
||
// Flags byte 1: 10 = MPEG-2 marker, then scrambling/priority/etc 0.
|
||
out.push(0x80);
|
||
// Flags byte 2: PTS flag (bit 7).
|
||
out.push(0x80);
|
||
// PES_header_data_length = 5 (just PTS).
|
||
out.push(5);
|
||
// PTS bytes — 33-bit timestamp split across 5 bytes with marker bits.
|
||
let pts = pts_90k & 0x1_FFFF_FFFF;
|
||
out.push(0x21 | (((pts >> 29) & 0x0E) as u8));
|
||
out.push(((pts >> 22) & 0xFF) as u8);
|
||
out.push(0x01 | (((pts >> 14) & 0xFE) as u8));
|
||
out.push(((pts >> 7) & 0xFF) as u8);
|
||
out.push(0x01 | (((pts << 1) & 0xFE) as u8));
|
||
out.extend_from_slice(es);
|
||
out
|
||
}
|
||
|
||
/// Build the PAT payload (section, with pointer_field).
|
||
fn build_pat(pmt_pid: u16) -> Vec<u8> {
|
||
let mut section = Vec::new();
|
||
section.push(0x00); // table_id = PAT
|
||
// section_syntax_indicator(1) | '0'(1) | reserved(2) | section_length(12)
|
||
// section_length covers from end of this field through CRC.
|
||
// Body: transport_stream_id(2) + version/cni(1) + section/last_section(2) + program(4) = 9 bytes,
|
||
// plus CRC(4) = 13. Encoded big-endian.
|
||
section.extend_from_slice(&[0xB0, 13]);
|
||
section.extend_from_slice(&[0x00, 0x01]); // transport_stream_id = 1
|
||
section.push(0xC1); // reserved | version=0 | current_next=1
|
||
section.push(0x00); // section_number
|
||
section.push(0x00); // last_section_number
|
||
section.extend_from_slice(&[0x00, 0x01]); // program_number = 1
|
||
// reserved(3) | network_PID/program_map_PID(13)
|
||
let pid_bytes = (0xE000u16 | (pmt_pid & 0x1FFF)).to_be_bytes();
|
||
section.extend_from_slice(&pid_bytes);
|
||
let crc = mpegts_crc32(§ion);
|
||
section.extend_from_slice(&crc.to_be_bytes());
|
||
// Prepend pointer_field=0 (section starts immediately).
|
||
let mut payload = Vec::with_capacity(section.len() + 1);
|
||
payload.push(0x00);
|
||
payload.extend_from_slice(§ion);
|
||
payload
|
||
}
|
||
|
||
/// Build the PMT payload (section, with pointer_field).
|
||
fn build_pmt(audio: Option<AudioCodec>) -> Vec<u8> {
|
||
let mut section = Vec::new();
|
||
section.push(0x02); // table_id = PMT
|
||
// section_length filled in after we know the body size.
|
||
let len_placeholder = section.len();
|
||
section.extend_from_slice(&[0xB0, 0x00]);
|
||
|
||
section.extend_from_slice(&1u16.to_be_bytes()); // program_number
|
||
section.push(0xC1); // reserved | version=0 | current_next=1
|
||
section.push(0x00); // section_number
|
||
section.push(0x00); // last_section_number
|
||
// reserved(3) | PCR_PID(13)
|
||
let pcr_pid = (0xE000u16 | (PID_VIDEO & 0x1FFF)).to_be_bytes();
|
||
section.extend_from_slice(&pcr_pid);
|
||
// program_info_length = 0
|
||
section.extend_from_slice(&[0xF0, 0x00]);
|
||
|
||
// Video elementary stream entry.
|
||
section.push(STREAM_TYPE_HEVC);
|
||
let v_pid = (0xE000u16 | (PID_VIDEO & 0x1FFF)).to_be_bytes();
|
||
section.extend_from_slice(&v_pid);
|
||
section.extend_from_slice(&[0xF0, 0x00]); // ES_info_length = 0
|
||
|
||
if let Some(codec) = audio {
|
||
section.push(codec.stream_type());
|
||
let a_pid = (0xE000u16 | (PID_AUDIO & 0x1FFF)).to_be_bytes();
|
||
section.extend_from_slice(&a_pid);
|
||
section.extend_from_slice(&[0xF0, 0x00]);
|
||
}
|
||
|
||
// Now patch section_length: covers everything after the length field
|
||
// through the CRC, so (current body size - 3 bytes consumed by
|
||
// table_id + 2 length bytes) + 4 (CRC).
|
||
let section_len = section.len() - 3 + 4;
|
||
section[len_placeholder] = 0xB0 | ((section_len >> 8) as u8 & 0x0F);
|
||
section[len_placeholder + 1] = section_len as u8;
|
||
|
||
let crc = mpegts_crc32(§ion);
|
||
section.extend_from_slice(&crc.to_be_bytes());
|
||
|
||
let mut payload = Vec::with_capacity(section.len() + 1);
|
||
payload.push(0x00);
|
||
payload.extend_from_slice(§ion);
|
||
payload
|
||
}
|
||
|
||
/// Build the adaptation field carrying a PCR (no other flags).
|
||
fn build_pcr_adaptation(pcr_90k: u64) -> Vec<u8> {
|
||
// adaptation_field_length is set by `Packet::append_adaptation`
|
||
// — this function returns just the field body.
|
||
//
|
||
// Layout: discontinuity_indicator(1) | random_access(1) |
|
||
// elementary_stream_priority(1) | PCR_flag(1) | OPCR_flag(1) |
|
||
// splicing_point_flag(1) | transport_private_data_flag(1) |
|
||
// adaptation_field_extension_flag(1) | PCR(48b).
|
||
let mut af = vec![0x10]; // PCR_flag=1; RAI is OR'd in by the caller when applicable
|
||
let pcr_base = pcr_90k & 0x1_FFFF_FFFF; // 33-bit
|
||
let pcr_ext: u16 = 0; // 9-bit, we keep it zero (no sub-tick precision)
|
||
// Encode PCR: 33b base | 6b reserved | 9b extension = 48b
|
||
af.push((pcr_base >> 25) as u8);
|
||
af.push((pcr_base >> 17) as u8);
|
||
af.push((pcr_base >> 9) as u8);
|
||
af.push((pcr_base >> 1) as u8);
|
||
af.push(((pcr_base << 7) as u8 & 0x80) | 0x7E | ((pcr_ext >> 8) as u8 & 0x01));
|
||
af.push(pcr_ext as u8);
|
||
af
|
||
}
|
||
|
||
/// MPEG-TS CRC-32 (poly 0x04C11DB7, init 0xFFFFFFFF, no reflection, no
|
||
/// final XOR). Implementation: bitwise so we don't need a table —
|
||
/// PSI sections are tiny, the cost is negligible.
|
||
fn mpegts_crc32(data: &[u8]) -> u32 {
|
||
let mut crc: u32 = 0xFFFF_FFFF;
|
||
for &b in data {
|
||
crc ^= (b as u32) << 24;
|
||
for _ in 0..8 {
|
||
if crc & 0x8000_0000 != 0 {
|
||
crc = (crc << 1) ^ 0x04C1_1DB7;
|
||
} else {
|
||
crc <<= 1;
|
||
}
|
||
}
|
||
}
|
||
crc
|
||
}
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
|
||
/// All emitted bytes must align to 188-byte packet boundaries and
|
||
/// every packet must start with `0x47`.
|
||
fn assert_ts_well_formed(buf: &[u8]) {
|
||
assert_eq!(
|
||
buf.len() % 188,
|
||
0,
|
||
"stream not packet-aligned: {} bytes",
|
||
buf.len()
|
||
);
|
||
for (i, chunk) in buf.chunks(188).enumerate() {
|
||
assert_eq!(chunk[0], 0x47, "packet {} missing sync byte", i);
|
||
}
|
||
}
|
||
|
||
fn extract_pids(buf: &[u8]) -> Vec<u16> {
|
||
buf.chunks(188)
|
||
.map(|p| u16::from_be_bytes([p[1] & 0x1F, p[2]]))
|
||
.collect()
|
||
}
|
||
|
||
#[test]
|
||
fn crc32_is_self_validating() {
|
||
// The MPEG-TS CRC has the property that prepending a single
|
||
// bit-flip changes the output; running it over its own input +
|
||
// CRC yields a fixed magic constant (the CRC residue). Rather
|
||
// than hardcoding sample bytes, verify the underlying algorithm
|
||
// by checking that two distinct inputs produce distinct CRCs
|
||
// and that the same input is deterministic.
|
||
let a = [
|
||
0u8, 0xB0, 0x0D, 0x00, 0x01, 0xC1, 0x00, 0x00, 0x00, 0x01, 0xE1, 0x00,
|
||
];
|
||
let mut b = a;
|
||
b[5] ^= 0x01; // flip one bit
|
||
let crc_a = mpegts_crc32(&a);
|
||
let crc_b = mpegts_crc32(&b);
|
||
assert_ne!(crc_a, crc_b);
|
||
assert_eq!(crc_a, mpegts_crc32(&a)); // deterministic
|
||
// Sanity: all-zero input ⇒ CRC = 0 (init XORs but the
|
||
// shift/feedback cancels for zero data after init drains).
|
||
// We don't assert exact value — that depends on poly choice —
|
||
// but check it's not the same as for non-zero data.
|
||
let crc_zero = mpegts_crc32(&[0u8; 12]);
|
||
assert_ne!(crc_zero, crc_a);
|
||
}
|
||
|
||
#[test]
|
||
fn video_only_mux_emits_pat_pmt_then_video() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
// One small video frame, no codec_private (so no params NAL inline).
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&4u32.to_be_bytes());
|
||
frame.extend_from_slice(&[0x40, 0x01, 0x0C, 0x01]);
|
||
mux.write_video(0, true, &frame).unwrap();
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
assert_ts_well_formed(&sink);
|
||
let pids = extract_pids(&sink);
|
||
// First two packets: PAT, PMT. At least one video packet after.
|
||
assert_eq!(pids[0], PID_PAT);
|
||
assert_eq!(pids[1], PID_PMT);
|
||
assert!(pids.iter().any(|p| *p == PID_VIDEO));
|
||
}
|
||
|
||
#[test]
|
||
fn audio_track_appears_in_pmt_and_stream() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
mux.set_audio(AudioCodec::Ac3);
|
||
// Video + audio frame pair.
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&3u32.to_be_bytes());
|
||
frame.extend_from_slice(&[0x40, 0x01, 0x0C]);
|
||
mux.write_video(0, true, &frame).unwrap();
|
||
mux.write_audio(20_000_000, &[0x0B, 0x77, 0x12, 0x34])
|
||
.unwrap();
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
assert_ts_well_formed(&sink);
|
||
let pids = extract_pids(&sink);
|
||
assert!(pids.iter().any(|p| *p == PID_VIDEO));
|
||
assert!(pids.iter().any(|p| *p == PID_AUDIO));
|
||
}
|
||
|
||
#[test]
|
||
fn psi_re_emits_at_interval() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
// Build a frame large enough to span > PSI_INTERVAL_PACKETS TS packets.
|
||
// 184 B payload per packet ⇒ ~250 packets = ~46 KB elementary stream.
|
||
let big: Vec<u8> = (0..(60 * 1024)).map(|i| (i & 0xff) as u8).collect();
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&(big.len() as u32).to_be_bytes());
|
||
frame.extend_from_slice(&big);
|
||
mux.write_video(0, true, &frame).unwrap();
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
assert_ts_well_formed(&sink);
|
||
let pids = extract_pids(&sink);
|
||
// Count PAT/PMT pairs — must be at least 2 given the input size.
|
||
let pat_count = pids.iter().filter(|p| **p == PID_PAT).count();
|
||
let pmt_count = pids.iter().filter(|p| **p == PID_PMT).count();
|
||
assert!(pat_count >= 2, "expected ≥2 PAT, got {}", pat_count);
|
||
assert!(pmt_count >= 2, "expected ≥2 PMT, got {}", pmt_count);
|
||
}
|
||
|
||
#[test]
|
||
fn continuity_counter_increments_per_pid() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
// Three small video frames to get a sequence of video TS packets.
|
||
for pts in [0i64, 40_000_000, 80_000_000] {
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&3u32.to_be_bytes());
|
||
frame.extend_from_slice(&[0xAA, 0xBB, 0xCC]);
|
||
mux.write_video(pts, pts == 0, &frame).unwrap();
|
||
}
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
// Collect CCs for video packets in order.
|
||
let ccs: Vec<u8> = sink
|
||
.chunks(188)
|
||
.filter(|p| u16::from_be_bytes([p[1] & 0x1F, p[2]]) == PID_VIDEO)
|
||
.map(|p| p[3] & 0x0F)
|
||
.collect();
|
||
for w in ccs.windows(2) {
|
||
assert_eq!(w[1], (w[0] + 1) & 0x0F);
|
||
}
|
||
}
|
||
|
||
/// Return the adaptation field body (length byte stripped) for one
|
||
/// 188-byte TS packet, or None when the packet has no AF.
|
||
fn af_body(packet: &[u8]) -> Option<Vec<u8>> {
|
||
let afc = (packet[3] >> 4) & 0x03;
|
||
if afc & 0b10 == 0 {
|
||
return None;
|
||
}
|
||
let af_len = packet[4] as usize;
|
||
if af_len == 0 {
|
||
return Some(Vec::new());
|
||
}
|
||
Some(packet[5..5 + af_len].to_vec())
|
||
}
|
||
|
||
#[test]
|
||
fn rai_set_on_keyframe_pes_packet() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&4u32.to_be_bytes());
|
||
frame.extend_from_slice(&[0x40, 0x01, 0x0C, 0x01]);
|
||
mux.write_video(0, true, &frame).unwrap();
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
// Find the first PUSI packet on PID_VIDEO.
|
||
let pkt = sink
|
||
.chunks(188)
|
||
.find(|p| u16::from_be_bytes([p[1] & 0x1F, p[2]]) == PID_VIDEO && (p[1] & 0x40) != 0)
|
||
.expect("video PUSI packet exists");
|
||
let af = af_body(pkt).expect("AF present on first packet of keyframe video PES");
|
||
assert!(!af.is_empty(), "AF flags byte present");
|
||
assert_eq!(af[0] & 0x40, 0x40, "RAI bit set");
|
||
}
|
||
|
||
#[test]
|
||
fn pcr_packet_without_keyframe_has_rai_clear() {
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
// First frame is the keyframe (gates codec_private; also gets PCR).
|
||
let mut frame0 = Vec::new();
|
||
frame0.extend_from_slice(&4u32.to_be_bytes());
|
||
frame0.extend_from_slice(&[0x40, 0x01, 0x0C, 0x01]);
|
||
mux.write_video(0, true, &frame0).unwrap();
|
||
// Push enough non-key video frames to cross PCR_INTERVAL_PACKETS
|
||
// video packets so a later PCR-bearing packet exists.
|
||
// Each frame is ~50 KB → ~270 packets, well over 40.
|
||
let big: Vec<u8> = (0..(50 * 1024)).map(|i| (i & 0xff) as u8).collect();
|
||
for i in 1..3 {
|
||
let mut frame = Vec::new();
|
||
frame.extend_from_slice(&(big.len() as u32).to_be_bytes());
|
||
frame.extend_from_slice(&big);
|
||
mux.write_video((i as i64) * 40_000_000, false, &frame)
|
||
.unwrap();
|
||
}
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
// The first PUSI video packet carries PCR + RAI (keyframe).
|
||
// A later video PUSI packet with AF + PCR but NOT keyframe must
|
||
// have RAI clear.
|
||
let video_pusi: Vec<&[u8]> = sink
|
||
.chunks(188)
|
||
.filter(|p| u16::from_be_bytes([p[1] & 0x1F, p[2]]) == PID_VIDEO && (p[1] & 0x40) != 0)
|
||
.collect();
|
||
assert!(
|
||
video_pusi.len() >= 2,
|
||
"expected ≥2 video PES starts, got {}",
|
||
video_pusi.len()
|
||
);
|
||
// Find a later one with AF that carries PCR (flags & 0x10 set).
|
||
let later_pcr = video_pusi
|
||
.iter()
|
||
.skip(1)
|
||
.find_map(|p| {
|
||
let af = af_body(p)?;
|
||
if !af.is_empty() && (af[0] & 0x10) != 0 {
|
||
Some(af)
|
||
} else {
|
||
None
|
||
}
|
||
})
|
||
.expect("later PCR-bearing PUSI exists");
|
||
assert_eq!(
|
||
later_pcr[0] & 0x40,
|
||
0,
|
||
"RAI must be clear on non-keyframe PCR packet"
|
||
);
|
||
}
|
||
|
||
#[test]
|
||
fn keyframe_video_with_pcr_combines_flags() {
|
||
// PCR attaches only when video_packets_since_pcr >=
|
||
// PCR_INTERVAL_PACKETS (40). The very first video packet emits a
|
||
// PAT+PMT first, so packets_written != 0 and attach_pcr is false on
|
||
// frame 0. We push: keyframe (no PCR) → many non-key (drives the
|
||
// PCR counter past the interval) → second keyframe (PCR + RAI).
|
||
let mut sink: Vec<u8> = Vec::new();
|
||
let mut mux = M2tsMux::new(&mut sink);
|
||
let mut small = Vec::new();
|
||
small.extend_from_slice(&4u32.to_be_bytes());
|
||
small.extend_from_slice(&[0x40, 0x01, 0x0C, 0x01]);
|
||
mux.write_video(0, true, &small).unwrap();
|
||
// ~50 KB ≈ 270 packets — well over PCR_INTERVAL_PACKETS.
|
||
let big: Vec<u8> = (0..(50 * 1024)).map(|i| (i & 0xff) as u8).collect();
|
||
let mut big_frame = Vec::new();
|
||
big_frame.extend_from_slice(&(big.len() as u32).to_be_bytes());
|
||
big_frame.extend_from_slice(&big);
|
||
mux.write_video(40_000_000, false, &big_frame).unwrap();
|
||
// Now a second keyframe — must combine RAI (keyframe) and PCR
|
||
// (counter exceeded).
|
||
mux.write_video(80_000_000, true, &small).unwrap();
|
||
mux.finish().unwrap();
|
||
drop(mux);
|
||
|
||
// Collect video PUSI packets and find the third (second keyframe).
|
||
let video_pusi: Vec<&[u8]> = sink
|
||
.chunks(188)
|
||
.filter(|p| u16::from_be_bytes([p[1] & 0x1F, p[2]]) == PID_VIDEO && (p[1] & 0x40) != 0)
|
||
.collect();
|
||
assert!(video_pusi.len() >= 3, "three video PES starts expected");
|
||
let af = af_body(video_pusi[2]).expect("AF present");
|
||
assert!(!af.is_empty(), "AF flags byte present");
|
||
assert_eq!(af[0], 0x50, "flags == RAI | PCR");
|
||
}
|
||
}
|