"""Provides the worker thread needed for processing streams.""" from __future__ import annotations from collections import defaultdict, deque from collections.abc import Callable, Generator, Iterator, Mapping import contextlib import datetime from io import BytesIO import logging from threading import Event from typing import Any, cast import av from homeassistant.core import HomeAssistant from . import redact_credentials from .const import ( ATTR_SETTINGS, AUDIO_CODECS, DOMAIN, HLS_PROVIDER, MAX_MISSING_DTS, MAX_TIMESTAMP_GAP, PACKETS_TO_WAIT_FOR_AUDIO, SEGMENT_CONTAINER_FORMAT, SOURCE_TIMEOUT, ) from .core import Part, Segment, StreamOutput, StreamSettings from .hls import HlsStreamOutput _LOGGER = logging.getLogger(__name__) class StreamWorkerError(Exception): """An exception thrown while processing a stream.""" class StreamEndedError(StreamWorkerError): """Raised when the stream is complete, exposed for facilitating testing.""" class StreamState: """Responsible for trakcing output and playback state for a stream. Holds state used for playback to interpret a decoded stream. A source stream may be reset (e.g. reconnecting to an rtsp stream) and this object tracks the state to inform the player. """ def __init__( self, hass: HomeAssistant, outputs_callback: Callable[[], Mapping[str, StreamOutput]], ) -> None: """Initialize StreamState.""" self._stream_id: int = 0 self.hass = hass self._outputs_callback: Callable[ [], Mapping[str, StreamOutput] ] = outputs_callback # sequence gets incremented before the first segment so the first segment # has a sequence number of 0. self._sequence = -1 @property def sequence(self) -> int: """Return the current sequence for the latest segment.""" return self._sequence def next_sequence(self) -> int: """Increment the sequence number.""" self._sequence += 1 return self._sequence @property def stream_id(self) -> int: """Return the readonly stream_id attribute.""" return self._stream_id def discontinuity(self) -> None: """Mark the stream as having been restarted.""" # Preserving sequence and stream_id here keep the HLS playlist logic # simple to check for discontinuity at output time, and to determine # the discontinuity sequence number. self._stream_id += 1 # Call discontinuity to remove incomplete segment from the HLS output if hls_output := self._outputs_callback().get(HLS_PROVIDER): cast(HlsStreamOutput, hls_output).discontinuity() @property def outputs(self) -> list[StreamOutput]: """Return the active stream outputs.""" return list(self._outputs_callback().values()) class StreamMuxer: """StreamMuxer re-packages video/audio packets for output.""" def __init__( self, hass: HomeAssistant, video_stream: av.video.VideoStream, audio_stream: av.audio.stream.AudioStream | None, stream_state: StreamState, ) -> None: """Initialize StreamMuxer.""" self._hass = hass self._segment_start_dts: int = cast(int, None) self._memory_file: BytesIO = cast(BytesIO, None) self._av_output: av.container.OutputContainer = None self._input_video_stream: av.video.VideoStream = video_stream self._input_audio_stream: av.audio.stream.AudioStream | None = audio_stream self._output_video_stream: av.video.VideoStream = None self._output_audio_stream: av.audio.stream.AudioStream | None = None self._segment: Segment | None = None # the following 3 member variables are used for Part formation self._memory_file_pos: int = cast(int, None) self._part_start_dts: int = cast(int, None) self._part_has_keyframe = False self._stream_settings: StreamSettings = hass.data[DOMAIN][ATTR_SETTINGS] self._stream_state = stream_state self._start_time = datetime.datetime.utcnow() def make_new_av( self, memory_file: BytesIO, sequence: int, input_vstream: av.video.VideoStream, input_astream: av.audio.stream.AudioStream | None, ) -> tuple[ av.container.OutputContainer, av.video.VideoStream, av.audio.stream.AudioStream | None, ]: """Make a new av OutputContainer and add output streams.""" container = av.open( memory_file, mode="w", format=SEGMENT_CONTAINER_FORMAT, container_options={ **{ # Removed skip_sidx - see https://github.com/home-assistant/core/pull/39970 # "cmaf" flag replaces several of the movflags used, but too recent to use for now "movflags": "frag_custom+empty_moov+default_base_moof+frag_discont+negative_cts_offsets+skip_trailer", # Sometimes the first segment begins with negative timestamps, and this setting just # adjusts the timestamps in the output from that segment to start from 0. Helps from # having to make some adjustments in test_durations "avoid_negative_ts": "make_non_negative", "fragment_index": str(sequence + 1), "video_track_timescale": str(int(1 / input_vstream.time_base)), }, # Only do extra fragmenting if we are using ll_hls # Let ffmpeg do the work using frag_duration # Fragment durations may exceed the 15% allowed variance but it seems ok **( { "movflags": "empty_moov+default_base_moof+frag_discont+negative_cts_offsets+skip_trailer", # Create a fragment every TARGET_PART_DURATION. The data from each fragment is stored in # a "Part" that can be combined with the data from all the other "Part"s, plus an init # section, to reconstitute the data in a "Segment". # The LL-HLS spec allows for a fragment's duration to be within the range [0.85x,1.0x] # of the part target duration. We use the frag_duration option to tell ffmpeg to try to # cut the fragments when they reach frag_duration. However, the resulting fragments can # have variability in their durations and can end up being too short or too long. With a # video track with no audio, the discrete nature of frames means that the frame at the # end of a fragment will sometimes extend slightly beyond the desired frag_duration. # If there are two tracks, as in the case of a video feed with audio, there is an added # wrinkle as the fragment cut seems to be done on the first track that crosses the desired # threshold, and cutting on the audio track may also result in a shorter video fragment # than desired. # Given this, our approach is to give ffmpeg a frag_duration somewhere in the middle # of the range, hoping that the parts stay pretty well bounded, and we adjust the part # durations a bit in the hls metadata so that everything "looks" ok. "frag_duration": str( self._stream_settings.part_target_duration * 9e5 ), } if self._stream_settings.ll_hls else {} ), }, ) output_vstream = container.add_stream(template=input_vstream) # Check if audio is requested output_astream = None if input_astream: output_astream = container.add_stream(template=input_astream) return container, output_vstream, output_astream def reset(self, video_dts: int) -> None: """Initialize a new stream segment.""" self._part_start_dts = self._segment_start_dts = video_dts self._segment = None self._memory_file = BytesIO() self._memory_file_pos = 0 ( self._av_output, self._output_video_stream, self._output_audio_stream, ) = self.make_new_av( memory_file=self._memory_file, sequence=self._stream_state.next_sequence(), input_vstream=self._input_video_stream, input_astream=self._input_audio_stream, ) if self._output_video_stream.name == "hevc": self._output_video_stream.codec_tag = "hvc1" def mux_packet(self, packet: av.Packet) -> None: """Mux a packet to the appropriate output stream.""" # Check for end of segment if packet.stream == self._input_video_stream: if ( packet.is_keyframe and (packet.dts - self._segment_start_dts) * packet.time_base >= self._stream_settings.min_segment_duration ): # Flush segment (also flushes the stub part segment) self.flush(packet, last_part=True) # Mux the packet packet.stream = self._output_video_stream self._av_output.mux(packet) self.check_flush_part(packet) self._part_has_keyframe |= packet.is_keyframe elif packet.stream == self._input_audio_stream: packet.stream = self._output_audio_stream self._av_output.mux(packet) def check_flush_part(self, packet: av.Packet) -> None: """Check for and mark a part segment boundary and record its duration.""" if self._memory_file_pos == self._memory_file.tell(): return if self._segment is None: # We have our first non-zero byte position. This means the init has just # been written. Create a Segment and put it to the queue of each output. self._segment = Segment( sequence=self._stream_state.sequence, stream_id=self._stream_state.stream_id, init=self._memory_file.getvalue(), # Fetch the latest StreamOutputs, which may have changed since the # worker started. stream_outputs=self._stream_state.outputs, start_time=self._start_time, ) self._memory_file_pos = self._memory_file.tell() else: # These are the ends of the part segments self.flush(packet, last_part=False) def flush(self, packet: av.Packet, last_part: bool) -> None: """Output a part from the most recent bytes in the memory_file. If last_part is True, also close the segment, give it a duration, and clean up the av_output and memory_file. There are two different ways to enter this function, and when last_part is True, packet has not yet been muxed, while when last_part is False, the packet has already been muxed. However, in both cases, packet is the next packet and is not included in the Part. This function writes the duration metadata for the Part and for the Segment. However, as the fragmentation done by ffmpeg may result in fragment durations which fall outside the [0.85x,1.0x] tolerance band allowed by LL-HLS, we need to fudge some durations a bit by reporting them as being within that range. Note that repeated adjustments may cause drift between the part durations in the metadata and those in the media and result in playback issues in some clients. """ # Part durations should not exceed the part target duration adjusted_dts = min( packet.dts, self._part_start_dts + self._stream_settings.part_target_duration / packet.time_base, ) if last_part: # Closing the av_output will write the remaining buffered data to the # memory_file as a new moof/mdat. self._av_output.close() elif not self._part_has_keyframe: # Parts which are not the last part or an independent part should # not have durations below 0.85 of the part target duration. adjusted_dts = max( adjusted_dts, self._part_start_dts + 0.85 * self._stream_settings.part_target_duration / packet.time_base, ) assert self._segment self._memory_file.seek(self._memory_file_pos) self._hass.loop.call_soon_threadsafe( self._segment.async_add_part, Part( duration=float( (adjusted_dts - self._part_start_dts) * packet.time_base ), has_keyframe=self._part_has_keyframe, data=self._memory_file.read(), ), ( segment_duration := float( (adjusted_dts - self._segment_start_dts) * packet.time_base ) ) if last_part else 0, ) if last_part: # If we've written the last part, we can close the memory_file. self._memory_file.close() # We don't need the BytesIO object anymore self._start_time += datetime.timedelta(seconds=segment_duration) # Reinitialize self.reset(packet.dts) else: # For the last part, these will get set again elsewhere so we can skip # setting them here. self._memory_file_pos = self._memory_file.tell() self._part_start_dts = adjusted_dts self._part_has_keyframe = False def close(self) -> None: """Close stream buffer.""" self._av_output.close() self._memory_file.close() class PeekIterator(Iterator): """An Iterator that may allow multiple passes. This may be consumed like a normal Iterator, however also supports a peek() method that buffers consumed items from the iterator. """ def __init__(self, iterator: Iterator[av.Packet]) -> None: """Initialize PeekIterator.""" self._iterator = iterator self._buffer: deque[av.Packet] = deque() # A pointer to either _iterator or _buffer self._next = self._iterator.__next__ def __iter__(self) -> Iterator: """Return an iterator.""" return self def __next__(self) -> av.Packet: """Return and consume the next item available.""" return self._next() def replace_underlying_iterator(self, new_iterator: Iterator) -> None: """Replace the underlying iterator while preserving the buffer.""" self._iterator = new_iterator if not self._buffer: self._next = self._iterator.__next__ def _pop_buffer(self) -> av.Packet: """Consume items from the buffer until exhausted.""" if self._buffer: return self._buffer.popleft() # The buffer is empty, so change to consume from the iterator self._next = self._iterator.__next__ return self._next() def peek(self) -> Generator[av.Packet, None, None]: """Return items without consuming from the iterator.""" # Items consumed are added to a buffer for future calls to __next__ # or peek. First iterate over the buffer from previous calls to peek. self._next = self._pop_buffer for packet in self._buffer: yield packet for packet in self._iterator: self._buffer.append(packet) yield packet class TimestampValidator: """Validate ordering of timestamps for packets in a stream.""" def __init__(self) -> None: """Initialize the TimestampValidator.""" # Decompression timestamp of last packet in each stream self._last_dts: dict[av.stream.Stream, int | float] = defaultdict( lambda: float("-inf") ) # Number of consecutive missing decompression timestamps self._missing_dts = 0 def is_valid(self, packet: av.Packet) -> bool: """Validate the packet timestamp based on ordering within the stream.""" # Discard packets missing DTS. Terminate if too many are missing. if packet.dts is None: if self._missing_dts >= MAX_MISSING_DTS: raise StreamWorkerError( f"No dts in {MAX_MISSING_DTS+1} consecutive packets" ) self._missing_dts += 1 return False self._missing_dts = 0 # Discard when dts is not monotonic. Terminate if gap is too wide. prev_dts = self._last_dts[packet.stream] if packet.dts <= prev_dts: gap = packet.time_base * (prev_dts - packet.dts) if gap > MAX_TIMESTAMP_GAP: raise StreamWorkerError( f"Timestamp overflow detected: last dts = {prev_dts}, dts = {packet.dts}" ) return False self._last_dts[packet.stream] = packet.dts return True def is_keyframe(packet: av.Packet) -> Any: """Return true if the packet is a keyframe.""" return packet.is_keyframe def unsupported_audio(packets: Iterator[av.Packet], audio_stream: Any) -> bool: """Detect ADTS AAC, which is not supported by pyav.""" if not audio_stream: return False for count, packet in enumerate(packets): if count >= PACKETS_TO_WAIT_FOR_AUDIO: # Some streams declare an audio stream and never send any packets _LOGGER.warning("Audio stream not found") break if packet.stream == audio_stream: # detect ADTS AAC and disable audio if audio_stream.codec.name == "aac" and packet.size > 2: with memoryview(packet) as packet_view: if packet_view[0] == 0xFF and packet_view[1] & 0xF0 == 0xF0: _LOGGER.warning("ADTS AAC detected - disabling audio stream") return True break return False def stream_worker( source: str, options: dict[str, str], stream_state: StreamState, quit_event: Event, ) -> None: """Handle consuming streams.""" try: container = av.open(source, options=options, timeout=SOURCE_TIMEOUT) except av.AVError as err: raise StreamWorkerError( "Error opening stream %s" % redact_credentials(str(source)) ) from err try: video_stream = container.streams.video[0] except (KeyError, IndexError) as ex: raise StreamWorkerError("Stream has no video") from ex try: audio_stream = container.streams.audio[0] except (KeyError, IndexError): audio_stream = None if audio_stream and audio_stream.name not in AUDIO_CODECS: audio_stream = None # These formats need aac_adtstoasc bitstream filter, but auto_bsf not # compatible with empty_moov and manual bitstream filters not in PyAV if container.format.name in {"hls", "mpegts"}: audio_stream = None # Some audio streams do not have a profile and throw errors when remuxing if audio_stream and audio_stream.profile is None: audio_stream = None dts_validator = TimestampValidator() container_packets = PeekIterator( filter(dts_validator.is_valid, container.demux((video_stream, audio_stream))) ) def is_video(packet: av.Packet) -> Any: """Return true if the packet is for the video stream.""" return packet.stream == video_stream # Have to work around two problems with RTSP feeds in ffmpeg # 1 - first frame has bad pts/dts https://trac.ffmpeg.org/ticket/5018 # 2 - seeking can be problematic https://trac.ffmpeg.org/ticket/7815 # # Use a peeking iterator to peek into the start of the stream, ensuring # everything looks good, then go back to the start when muxing below. try: if audio_stream and unsupported_audio(container_packets.peek(), audio_stream): audio_stream = None container_packets.replace_underlying_iterator( filter(dts_validator.is_valid, container.demux(video_stream)) ) # Advance to the first keyframe for muxing, then rewind so the muxing # loop below can consume. first_keyframe = next( filter(lambda pkt: is_keyframe(pkt) and is_video(pkt), container_packets) ) # Deal with problem #1 above (bad first packet pts/dts) by recalculating # using pts/dts from second packet. Use the peek iterator to advance # without consuming from container_packets. Skip over the first keyframe # then use the duration from the second video packet to adjust dts. next_video_packet = next(filter(is_video, container_packets.peek())) # Since the is_valid filter has already been applied before the following # adjustment, it does not filter out the case where the duration below is # 0 and both the first_keyframe and next_video_packet end up with the same # dts. Use "or 1" to deal with this. start_dts = next_video_packet.dts - (next_video_packet.duration or 1) first_keyframe.dts = first_keyframe.pts = start_dts except StreamWorkerError as ex: container.close() raise ex except StopIteration as ex: container.close() raise StreamEndedError("Stream ended; no additional packets") from ex except av.AVError as ex: container.close() raise StreamWorkerError( "Error demuxing stream while finding first packet: %s" % str(ex) ) from ex muxer = StreamMuxer(stream_state.hass, video_stream, audio_stream, stream_state) muxer.reset(start_dts) # Mux the first keyframe, then proceed through the rest of the packets muxer.mux_packet(first_keyframe) with contextlib.closing(container), contextlib.closing(muxer): while not quit_event.is_set(): try: packet = next(container_packets) except StreamWorkerError as ex: raise ex except StopIteration as ex: raise StreamEndedError("Stream ended; no additional packets") from ex except av.AVError as ex: raise StreamWorkerError("Error demuxing stream: %s" % str(ex)) from ex muxer.mux_packet(packet)