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439 lines
18 KiB
Rust
439 lines
18 KiB
Rust
// This file is part of Moonfire NVR, a security camera network video recorder.
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// Copyright (C) 2021 The Moonfire NVR Authors; see AUTHORS and LICENSE.txt.
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// SPDX-License-Identifier: GPL-v3.0-or-later WITH GPL-3.0-linking-exception.
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//! H.264 decoding
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//!
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//! For the most part, Moonfire NVR does not try to understand the video codec. However, H.264 has
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//! two byte stream encodings: ISO/IEC 14496-10 Annex B, and ISO/IEC 14496-15 AVC access units.
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//! When streaming from RTSP, ffmpeg supplies the former. We need the latter to stick into `.mp4`
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//! files. This file manages the conversion, both for the ffmpeg "extra data" (which should become
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//! the ISO/IEC 14496-15 section 5.2.4.1 `AVCDecoderConfigurationRecord`) and the actual samples.
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//!
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//! See the [wiki page on standards and
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//! specifications](https://github.com/scottlamb/moonfire-nvr/wiki/Standards-and-specifications)
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//! for help finding a copy of the relevant standards. This code won't make much sense without them!
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//!
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//! ffmpeg of course has logic to do the same thing, but unfortunately it is not exposed except
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//! through ffmpeg's own generated `.mp4` file. Extracting just this part of their `.mp4` files
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//! would be more trouble than it's worth.
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use byteorder::{BigEndian, ByteOrder, WriteBytesExt};
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use failure::{bail, format_err, Error};
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use std::convert::TryFrom;
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// See ISO/IEC 14496-10 table 7-1 - NAL unit type codes, syntax element categories, and NAL unit
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// type classes.
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const NAL_UNIT_SEQ_PARAMETER_SET: u8 = 7;
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const NAL_UNIT_PIC_PARAMETER_SET: u8 = 8;
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const NAL_UNIT_TYPE_MASK: u8 = 0x1F; // bottom 5 bits of first byte of unit.
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// For certain common sub stream anamorphic resolutions, add a pixel aspect ratio box.
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// Assume the camera is 16x9. These are just the standard wide mode; default_pixel_aspect_ratio
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// tries the transpose also.
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const PIXEL_ASPECT_RATIOS: [((u16, u16), (u16, u16)); 6] = [
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((320, 240), (4, 3)),
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((352, 240), (40, 33)),
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((640, 352), (44, 45)),
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((640, 480), (4, 3)),
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((704, 480), (40, 33)),
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((720, 480), (32, 27)),
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];
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/// Get the pixel aspect ratio to use if none is specified.
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///
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/// The Dahua IPC-HDW5231R-Z sets the aspect ratio in the H.264 SPS (correctly) for both square and
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/// non-square pixels. The Hikvision DS-2CD2032-I doesn't set it, even though the sub stream's
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/// pixels aren't square. So define a default based on the pixel dimensions to use if the camera
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/// doesn't tell us what to do.
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///
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/// Note that at least in the case of .mp4 muxing, we don't need to fix up the underlying SPS.
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/// SPS; PixelAspectRatioBox's definition says that it overrides the H.264-level declaration.
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fn default_pixel_aspect_ratio(width: u16, height: u16) -> (u16, u16) {
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if width >= height {
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PIXEL_ASPECT_RATIOS
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.iter()
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.find(|r| r.0 == (width, height))
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.map(|r| r.1)
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.unwrap_or((1, 1))
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} else {
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PIXEL_ASPECT_RATIOS
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.iter()
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.find(|r| r.0 == (height, width))
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.map(|r| (r.1 .1, r.1 .0))
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.unwrap_or((1, 1))
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}
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}
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/// Decodes a H.264 Annex B byte stream into NAL units. Calls `f` for each NAL unit in the byte
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/// stream. Aborts if `f` returns error.
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///
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/// Note `f` is called with the encoded NAL form, not the RBSP. The NAL header byte and any
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/// emulation prevention bytes will be present.
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///
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/// See ISO/IEC 14496-10 section B.2: Byte stream NAL unit decoding process.
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/// This is a relatively simple, unoptimized implementation.
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///
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/// TODO: detect invalid byte streams. For example, several 0x00s not followed by a 0x01, a stream
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/// stream not starting with 0x00 0x00 0x00 0x01, or an empty NAL unit.
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fn decode_h264_annex_b<'a, F>(mut data: &'a [u8], mut f: F) -> Result<(), Error>
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where
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F: FnMut(&'a [u8]) -> Result<(), Error>,
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{
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let start_code = &b"\x00\x00\x01"[..];
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use nom::FindSubstring;
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'outer: while let Some(pos) = data.find_substring(start_code) {
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let mut unit = &data[0..pos];
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data = &data[pos + start_code.len()..];
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// Have zero or more bytes that end in a start code. Strip out any trailing 0x00s and
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// process the unit if there's anything left.
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loop {
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match unit.last() {
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None => continue 'outer,
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Some(b) if *b == 0 => {
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unit = &unit[..unit.len() - 1];
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}
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Some(_) => break,
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}
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}
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f(unit)?;
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}
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// No remaining start codes; likely a unit left.
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if !data.is_empty() {
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f(data)?;
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}
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Ok(())
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}
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/// Parses Annex B extra data, returning a tuple holding the `sps` and `pps` substrings.
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fn parse_annex_b_extra_data(data: &[u8]) -> Result<(&[u8], &[u8]), Error> {
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let mut sps = None;
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let mut pps = None;
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decode_h264_annex_b(data, |unit| {
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let nal_type = (unit[0] as u8) & NAL_UNIT_TYPE_MASK;
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match nal_type {
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NAL_UNIT_SEQ_PARAMETER_SET => sps = Some(unit),
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NAL_UNIT_PIC_PARAMETER_SET => pps = Some(unit),
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_ => bail!("Expected SPS and PPS; got type {}", nal_type),
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};
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Ok(())
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})?;
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match (sps, pps) {
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(Some(s), Some(p)) => Ok((s, p)),
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_ => bail!("SPS and PPS must be specified"),
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}
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}
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/// Parsed representation of ffmpeg's "extradata".
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#[derive(Debug, PartialEq, Eq)]
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pub struct ExtraData {
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pub entry: db::VideoSampleEntryToInsert,
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/// True iff sample data should be transformed from Annex B format to AVC format via a call to
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/// `transform_sample_data`. (The assumption is that if the extra data was in Annex B format,
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/// the sample data is also.)
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pub need_transform: bool,
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}
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impl ExtraData {
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/// Parses "extradata" from ffmpeg. This data may be in either Annex B format or AVC format.
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pub fn parse(extradata: &[u8], width: u16, height: u16) -> Result<ExtraData, Error> {
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let raw_sps_and_pps;
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let need_transform;
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let ctx;
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let sps_owner;
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let sps; // reference to either within ctx or to sps_owner.
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if extradata.starts_with(b"\x00\x00\x00\x01") || extradata.starts_with(b"\x00\x00\x01") {
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// ffmpeg supplied "extradata" in Annex B format.
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let (s, p) = parse_annex_b_extra_data(extradata)?;
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let rbsp = h264_reader::rbsp::decode_nal(&s[1..]);
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sps_owner = h264_reader::nal::sps::SeqParameterSet::from_bytes(&rbsp)
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.map_err(|e| format_err!("Bad SPS: {:?}", e))?;
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sps = &sps_owner;
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raw_sps_and_pps = Some((s, p));
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need_transform = true;
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} else {
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// Assume "extradata" holds an AVCDecoderConfiguration.
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need_transform = false;
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raw_sps_and_pps = None;
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let avcc = h264_reader::avcc::AvcDecoderConfigurationRecord::try_from(extradata)
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.map_err(|e| format_err!("Bad AvcDecoderConfigurationRecord: {:?}", e))?;
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if avcc.num_of_sequence_parameter_sets() != 1 {
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bail!("Multiple SPSs!");
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}
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ctx = avcc
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.create_context(())
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.map_err(|e| format_err!("Can't load SPS+PPS: {:?}", e))?;
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sps = ctx
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.sps_by_id(h264_reader::nal::pps::ParamSetId::from_u32(0).unwrap())
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.ok_or_else(|| format_err!("No SPS 0"))?;
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};
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let mut sample_entry = Vec::with_capacity(256);
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// This is a concatenation of the following boxes/classes.
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// SampleEntry, ISO/IEC 14496-12 section 8.5.2.
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let avc1_len_pos = sample_entry.len();
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// length placeholder + type + reserved + data_reference_index = 1
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sample_entry.extend_from_slice(b"\x00\x00\x00\x00avc1\x00\x00\x00\x00\x00\x00\x00\x01");
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// VisualSampleEntry, ISO/IEC 14496-12 section 12.1.3.
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sample_entry.extend_from_slice(&[0; 16]); // pre-defined + reserved
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sample_entry.write_u16::<BigEndian>(width)?;
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sample_entry.write_u16::<BigEndian>(height)?;
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sample_entry.extend_from_slice(&[
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0x00, 0x48, 0x00, 0x00, // horizresolution
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0x00, 0x48, 0x00, 0x00, // vertresolution
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0x00, 0x00, 0x00, 0x00, // reserved
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0x00, 0x01, // frame count
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0x00, 0x00, 0x00, 0x00, // compressorname
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x00, 0x00, 0x00, //
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0x00, 0x18, 0xff, 0xff, // depth + pre_defined
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]);
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// AVCSampleEntry, ISO/IEC 14496-15 section 5.3.4.1.
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// AVCConfigurationBox, ISO/IEC 14496-15 section 5.3.4.1.
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let avcc_len_pos = sample_entry.len();
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sample_entry.extend_from_slice(b"\x00\x00\x00\x00avcC");
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if let Some((sps, pps)) = raw_sps_and_pps {
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// Create the AVCDecoderConfiguration, ISO/IEC 14496-15 section 5.2.4.1.
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// The beginning of the AVCDecoderConfiguration takes a few values from
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// the SPS (ISO/IEC 14496-10 section 7.3.2.1.1). One caveat: that section
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// defines the syntax in terms of RBSP, not NAL. The difference is the
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// escaping of 00 00 01 and 00 00 02; see notes about
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// "emulation_prevention_three_byte" in ISO/IEC 14496-10 section 7.4.
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// It looks like 00 is not a valid value of profile_idc, so this distinction
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// shouldn't be relevant here. And ffmpeg seems to ignore it.
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sample_entry.push(1); // configurationVersion
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sample_entry.push(sps[1]); // profile_idc . AVCProfileIndication
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sample_entry.push(sps[2]); // ...misc bits... . profile_compatibility
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sample_entry.push(sps[3]); // level_idc . AVCLevelIndication
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// Hardcode lengthSizeMinusOne to 3, matching TransformSampleData's 4-byte
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// lengths.
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sample_entry.push(0xff);
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// Only support one SPS and PPS.
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// ffmpeg's ff_isom_write_avcc has the same limitation, so it's probably
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// fine. This next byte is a reserved 0b111 + a 5-bit # of SPSs (1).
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sample_entry.push(0xe1);
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sample_entry.write_u16::<BigEndian>(u16::try_from(sps.len())?)?;
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sample_entry.extend_from_slice(sps);
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sample_entry.push(1); // # of PPSs.
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sample_entry.write_u16::<BigEndian>(u16::try_from(pps.len())?)?;
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sample_entry.extend_from_slice(pps);
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} else {
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sample_entry.extend_from_slice(extradata);
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};
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// Fix up avc1 and avcC box lengths.
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let cur_pos = sample_entry.len();
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BigEndian::write_u32(
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&mut sample_entry[avcc_len_pos..avcc_len_pos + 4],
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u32::try_from(cur_pos - avcc_len_pos)?,
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);
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// PixelAspectRatioBox, ISO/IEC 14496-12 section 12.1.4.2.
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// Write a PixelAspectRatioBox if necessary, as the sub streams can be be anamorphic.
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let pasp = sps
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.vui_parameters
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.as_ref()
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.and_then(|v| v.aspect_ratio_info.as_ref())
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.and_then(|a| a.clone().get())
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.unwrap_or_else(|| default_pixel_aspect_ratio(width, height));
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if pasp != (1, 1) {
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sample_entry.extend_from_slice(b"\x00\x00\x00\x10pasp"); // length + box name
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sample_entry.write_u32::<BigEndian>(pasp.0.into())?;
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sample_entry.write_u32::<BigEndian>(pasp.1.into())?;
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}
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let cur_pos = sample_entry.len();
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BigEndian::write_u32(
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&mut sample_entry[avc1_len_pos..avc1_len_pos + 4],
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u32::try_from(cur_pos - avc1_len_pos)?,
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);
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let profile_idc = sample_entry[103];
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let constraint_flags = sample_entry[104];
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let level_idc = sample_entry[105];
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let rfc6381_codec = format!(
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"avc1.{:02x}{:02x}{:02x}",
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profile_idc, constraint_flags, level_idc
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);
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Ok(ExtraData {
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entry: db::VideoSampleEntryToInsert {
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data: sample_entry,
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rfc6381_codec,
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width,
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height,
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pasp_h_spacing: pasp.0,
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pasp_v_spacing: pasp.1,
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},
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need_transform,
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})
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}
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}
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/// Transforms sample data from Annex B format to AVC format. Should be called on samples iff
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/// `ExtraData::need_transform` is true. Uses an out parameter `avc_sample` rather than a return
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/// so that memory allocations can be reused from sample to sample.
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pub fn transform_sample_data(annexb_sample: &[u8], avc_sample: &mut Vec<u8>) -> Result<(), Error> {
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// See AVCParameterSamples, ISO/IEC 14496-15 section 5.3.2.
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avc_sample.clear();
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// The output will be about as long as the input. Annex B stop codes require at least three
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// bytes; many seem to be four. The output lengths are exactly four.
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avc_sample.reserve(annexb_sample.len() + 4);
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decode_h264_annex_b(annexb_sample, |unit| {
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// 4-byte length; this must match ParseExtraData's lengthSizeMinusOne == 3.
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avc_sample.write_u32::<BigEndian>(unit.len() as u32)?; // length
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avc_sample.extend_from_slice(unit);
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Ok(())
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})?;
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Ok(())
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}
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#[cfg(test)]
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mod tests {
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use db::testutil;
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#[rustfmt::skip]
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const ANNEX_B_TEST_INPUT: [u8; 35] = [
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0x00, 0x00, 0x00, 0x01, 0x67, 0x4d, 0x00, 0x1f,
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0x9a, 0x66, 0x02, 0x80, 0x2d, 0xff, 0x35, 0x01,
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0x01, 0x01, 0x40, 0x00, 0x00, 0xfa, 0x00, 0x00,
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0x1d, 0x4c, 0x01, 0x00, 0x00, 0x00, 0x01, 0x68,
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0xee, 0x3c, 0x80,
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];
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#[rustfmt::skip]
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const AVC_DECODER_CONFIG_TEST_INPUT: [u8; 38] = [
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0x01, 0x4d, 0x00, 0x1f, 0xff, 0xe1, 0x00, 0x17,
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0x67, 0x4d, 0x00, 0x1f, 0x9a, 0x66, 0x02, 0x80,
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0x2d, 0xff, 0x35, 0x01, 0x01, 0x01, 0x40, 0x00,
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0x00, 0xfa, 0x00, 0x00, 0x1d, 0x4c, 0x01, 0x01,
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0x00, 0x04, 0x68, 0xee, 0x3c, 0x80,
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];
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#[rustfmt::skip]
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const TEST_OUTPUT: [u8; 132] = [
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0x00, 0x00, 0x00, 0x84, 0x61, 0x76, 0x63, 0x31,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x05, 0x00, 0x02, 0xd0, 0x00, 0x48, 0x00, 0x00,
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0x00, 0x48, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x18, 0xff, 0xff, 0x00, 0x00,
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0x00, 0x2e, 0x61, 0x76, 0x63, 0x43, 0x01, 0x4d,
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0x00, 0x1f, 0xff, 0xe1, 0x00, 0x17, 0x67, 0x4d,
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0x00, 0x1f, 0x9a, 0x66, 0x02, 0x80, 0x2d, 0xff,
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0x35, 0x01, 0x01, 0x01, 0x40, 0x00, 0x00, 0xfa,
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0x00, 0x00, 0x1d, 0x4c, 0x01, 0x01, 0x00, 0x04,
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0x68, 0xee, 0x3c, 0x80,
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];
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#[test]
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fn test_decode() {
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testutil::init();
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let data = &ANNEX_B_TEST_INPUT;
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let mut pieces = Vec::new();
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super::decode_h264_annex_b(data, |p| {
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pieces.push(p);
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Ok(())
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})
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.unwrap();
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assert_eq!(&pieces, &[&data[4..27], &data[31..]]);
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}
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#[test]
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fn test_sample_entry_from_avc_decoder_config() {
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testutil::init();
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let e = super::ExtraData::parse(&AVC_DECODER_CONFIG_TEST_INPUT, 1280, 720).unwrap();
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assert_eq!(&e.entry.data[..], &TEST_OUTPUT[..]);
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assert_eq!(e.entry.width, 1280);
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assert_eq!(e.entry.height, 720);
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assert_eq!(e.entry.rfc6381_codec, "avc1.4d001f");
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assert_eq!(e.need_transform, false);
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}
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#[test]
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fn test_sample_entry_from_annex_b() {
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testutil::init();
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let e = super::ExtraData::parse(&ANNEX_B_TEST_INPUT, 1280, 720).unwrap();
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assert_eq!(e.entry.width, 1280);
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assert_eq!(e.entry.height, 720);
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assert_eq!(e.entry.rfc6381_codec, "avc1.4d001f");
|
|
assert_eq!(e.need_transform, true);
|
|
}
|
|
|
|
#[test]
|
|
fn test_transform_sample_data() {
|
|
testutil::init();
|
|
#[rustfmt::skip]
|
|
const INPUT: [u8; 64] = [
|
|
0x00, 0x00, 0x00, 0x01, 0x67, 0x4d, 0x00, 0x1f,
|
|
0x9a, 0x66, 0x02, 0x80, 0x2d, 0xff, 0x35, 0x01,
|
|
0x01, 0x01, 0x40, 0x00, 0x00, 0xfa, 0x00, 0x00,
|
|
0x1d, 0x4c, 0x01,
|
|
|
|
0x00, 0x00, 0x00, 0x01, 0x68, 0xee, 0x3c, 0x80,
|
|
|
|
0x00, 0x00, 0x00, 0x01, 0x06, 0x06, 0x01, 0xc4,
|
|
0x80,
|
|
|
|
0x00, 0x00, 0x00, 0x01, 0x65, 0x88, 0x80, 0x10,
|
|
0x00, 0x08, 0x7f, 0x00, 0x5d, 0x27, 0xb5, 0xc1,
|
|
0xff, 0x8c, 0xd6, 0x35,
|
|
// (truncated)
|
|
];
|
|
#[rustfmt::skip]
|
|
const EXPECTED_OUTPUT: [u8; 64] = [
|
|
0x00, 0x00, 0x00, 0x17, 0x67, 0x4d, 0x00, 0x1f,
|
|
0x9a, 0x66, 0x02, 0x80, 0x2d, 0xff, 0x35, 0x01,
|
|
0x01, 0x01, 0x40, 0x00, 0x00, 0xfa, 0x00, 0x00,
|
|
0x1d, 0x4c, 0x01,
|
|
|
|
0x00, 0x00, 0x00, 0x04, 0x68, 0xee, 0x3c, 0x80,
|
|
|
|
0x00, 0x00, 0x00, 0x05, 0x06, 0x06, 0x01, 0xc4,
|
|
0x80,
|
|
|
|
0x00, 0x00, 0x00, 0x10, 0x65, 0x88, 0x80, 0x10,
|
|
0x00, 0x08, 0x7f, 0x00, 0x5d, 0x27, 0xb5, 0xc1,
|
|
0xff, 0x8c, 0xd6, 0x35,
|
|
];
|
|
let mut out = Vec::new();
|
|
super::transform_sample_data(&INPUT, &mut out).unwrap();
|
|
assert_eq!(&out[..], &EXPECTED_OUTPUT[..]);
|
|
}
|
|
|
|
#[test]
|
|
fn pixel_aspect_ratios() {
|
|
use super::default_pixel_aspect_ratio;
|
|
use num_rational::Ratio;
|
|
for &((w, h), _) in &super::PIXEL_ASPECT_RATIOS {
|
|
let (h_spacing, v_spacing) = default_pixel_aspect_ratio(w, h);
|
|
assert_eq!(Ratio::new(w * h_spacing, h * v_spacing), Ratio::new(16, 9));
|
|
|
|
// 90 or 270 degree rotation.
|
|
let (h_spacing, v_spacing) = default_pixel_aspect_ratio(h, w);
|
|
assert_eq!(Ratio::new(h * h_spacing, w * v_spacing), Ratio::new(9, 16));
|
|
}
|
|
}
|
|
}
|