314 lines
12 KiB
Python
314 lines
12 KiB
Python
"""Provides the worker thread needed for processing streams."""
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from __future__ import annotations
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from collections import deque
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from io import BytesIO
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import logging
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from typing import cast
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import av
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from . import redact_credentials
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from .const import (
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AUDIO_CODECS,
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MAX_MISSING_DTS,
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MAX_TIMESTAMP_GAP,
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MIN_SEGMENT_DURATION,
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PACKETS_TO_WAIT_FOR_AUDIO,
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SEGMENT_CONTAINER_FORMAT,
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STREAM_TIMEOUT,
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)
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from .core import Segment, StreamOutput
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from .fmp4utils import get_init_and_moof_data
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_LOGGER = logging.getLogger(__name__)
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class SegmentBuffer:
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"""Buffer for writing a sequence of packets to the output as a segment."""
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def __init__(self, outputs_callback) -> None:
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"""Initialize SegmentBuffer."""
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self._stream_id = 0
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self._outputs_callback = outputs_callback
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self._outputs: list[StreamOutput] = []
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self._sequence = 0
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self._segment_start_pts = None
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self._memory_file: BytesIO = cast(BytesIO, None)
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self._av_output: av.container.OutputContainer = None
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self._input_video_stream: av.video.VideoStream = None
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self._input_audio_stream = None # av.audio.AudioStream | None
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self._output_video_stream: av.video.VideoStream = None
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self._output_audio_stream = None # av.audio.AudioStream | None
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self._segment: Segment = cast(Segment, None)
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@staticmethod
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def make_new_av(
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memory_file: BytesIO, sequence: int, input_vstream: av.video.VideoStream
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) -> av.container.OutputContainer:
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"""Make a new av OutputContainer."""
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return av.open(
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memory_file,
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mode="w",
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format=SEGMENT_CONTAINER_FORMAT,
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container_options={
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# Removed skip_sidx - see https://github.com/home-assistant/core/pull/39970
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# "cmaf" flag replaces several of the movflags used, but too recent to use for now
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"movflags": "frag_custom+empty_moov+default_base_moof+frag_discont+negative_cts_offsets+skip_trailer",
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"avoid_negative_ts": "disabled",
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"fragment_index": str(sequence + 1),
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"video_track_timescale": str(int(1 / input_vstream.time_base)),
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},
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)
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def set_streams(
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self,
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video_stream: av.video.VideoStream,
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audio_stream,
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# no type hint for audio_stream until https://github.com/PyAV-Org/PyAV/pull/775 is merged
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) -> None:
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"""Initialize output buffer with streams from container."""
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self._input_video_stream = video_stream
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self._input_audio_stream = audio_stream
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def reset(self, video_pts):
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"""Initialize a new stream segment."""
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# Keep track of the number of segments we've processed
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self._sequence += 1
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self._segment_start_pts = video_pts
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# Fetch the latest StreamOutputs, which may have changed since the
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# worker started.
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self._outputs = self._outputs_callback().values()
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self._memory_file = BytesIO()
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self._av_output = self.make_new_av(
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memory_file=self._memory_file,
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sequence=self._sequence,
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input_vstream=self._input_video_stream,
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)
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self._output_video_stream = self._av_output.add_stream(
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template=self._input_video_stream
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)
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# Check if audio is requested
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self._output_audio_stream = None
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if self._input_audio_stream and self._input_audio_stream.name in AUDIO_CODECS:
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self._output_audio_stream = self._av_output.add_stream(
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template=self._input_audio_stream
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)
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def mux_packet(self, packet):
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"""Mux a packet to the appropriate output stream."""
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# Check for end of segment
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if packet.stream == self._input_video_stream and packet.is_keyframe:
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duration = (packet.pts - self._segment_start_pts) * packet.time_base
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if duration >= MIN_SEGMENT_DURATION:
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# Save segment to outputs
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self.flush(duration)
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# Reinitialize
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self.reset(packet.pts)
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# Mux the packet
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if packet.stream == self._input_video_stream:
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packet.stream = self._output_video_stream
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self._av_output.mux(packet)
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elif packet.stream == self._input_audio_stream:
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packet.stream = self._output_audio_stream
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self._av_output.mux(packet)
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def flush(self, duration):
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"""Create a segment from the buffered packets and write to output."""
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self._av_output.close()
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segment = Segment(
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self._sequence,
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*get_init_and_moof_data(self._memory_file.getbuffer()),
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duration,
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self._stream_id,
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)
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self._memory_file.close()
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for stream_output in self._outputs:
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stream_output.put(segment)
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def discontinuity(self):
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"""Mark the stream as having been restarted."""
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# Preserving sequence and stream_id here keep the HLS playlist logic
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# simple to check for discontinuity at output time, and to determine
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# the discontinuity sequence number.
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self._stream_id += 1
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def close(self):
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"""Close stream buffer."""
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self._av_output.close()
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self._memory_file.close()
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def stream_worker(source, options, segment_buffer, quit_event): # noqa: C901
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"""Handle consuming streams."""
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try:
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container = av.open(source, options=options, timeout=STREAM_TIMEOUT)
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except av.AVError:
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_LOGGER.error("Error opening stream %s", redact_credentials(str(source)))
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return
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try:
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video_stream = container.streams.video[0]
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except (KeyError, IndexError):
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_LOGGER.error("Stream has no video")
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container.close()
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return
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try:
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audio_stream = container.streams.audio[0]
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except (KeyError, IndexError):
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audio_stream = None
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# These formats need aac_adtstoasc bitstream filter, but auto_bsf not
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# compatible with empty_moov and manual bitstream filters not in PyAV
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if container.format.name in {"hls", "mpegts"}:
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audio_stream = None
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# Some audio streams do not have a profile and throw errors when remuxing
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if audio_stream and audio_stream.profile is None:
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audio_stream = None
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# Iterator for demuxing
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container_packets = None
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# The decoder timestamps of the latest packet in each stream we processed
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last_dts = {video_stream: float("-inf"), audio_stream: float("-inf")}
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# Keep track of consecutive packets without a dts to detect end of stream.
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missing_dts = 0
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# The video pts at the beginning of the segment
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segment_start_pts = None
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# Because of problems 1 and 2 below, we need to store the first few packets and replay them
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initial_packets = deque()
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# Have to work around two problems with RTSP feeds in ffmpeg
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# 1 - first frame has bad pts/dts https://trac.ffmpeg.org/ticket/5018
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# 2 - seeking can be problematic https://trac.ffmpeg.org/ticket/7815
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def peek_first_pts():
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"""Initialize by peeking into the first few packets of the stream.
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Deal with problem #1 above (bad first packet pts/dts) by recalculating using pts/dts from second packet.
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Also load the first video keyframe pts into segment_start_pts and check if the audio stream really exists.
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"""
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nonlocal segment_start_pts, audio_stream, container_packets
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missing_dts = 0
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found_audio = False
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try:
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container_packets = container.demux((video_stream, audio_stream))
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first_packet = None
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# Get to first video keyframe
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while first_packet is None:
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packet = next(container_packets)
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if (
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packet.dts is None
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): # Allow MAX_MISSING_DTS packets with no dts, raise error on the next one
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if missing_dts >= MAX_MISSING_DTS:
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raise StopIteration(
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f"Invalid data - got {MAX_MISSING_DTS+1} packets with missing DTS while initializing"
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)
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missing_dts += 1
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continue
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if packet.stream == audio_stream:
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found_audio = True
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elif packet.is_keyframe: # video_keyframe
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first_packet = packet
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initial_packets.append(packet)
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# Get first_pts from subsequent frame to first keyframe
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while segment_start_pts is None or (
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audio_stream
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and not found_audio
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and len(initial_packets) < PACKETS_TO_WAIT_FOR_AUDIO
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):
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packet = next(container_packets)
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if (
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packet.dts is None
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): # Allow MAX_MISSING_DTS packet with no dts, raise error on the next one
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if missing_dts >= MAX_MISSING_DTS:
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raise StopIteration(
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f"Invalid data - got {MAX_MISSING_DTS+1} packets with missing DTS while initializing"
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)
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missing_dts += 1
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continue
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if packet.stream == audio_stream:
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# detect ADTS AAC and disable audio
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if audio_stream.codec.name == "aac" and packet.size > 2:
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with memoryview(packet) as packet_view:
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if packet_view[0] == 0xFF and packet_view[1] & 0xF0 == 0xF0:
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_LOGGER.warning(
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"ADTS AAC detected - disabling audio stream"
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)
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container_packets = container.demux(video_stream)
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audio_stream = None
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continue
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found_audio = True
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elif (
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segment_start_pts is None
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): # This is the second video frame to calculate first_pts from
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segment_start_pts = packet.dts - packet.duration
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first_packet.pts = segment_start_pts
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first_packet.dts = segment_start_pts
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initial_packets.append(packet)
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if audio_stream and not found_audio:
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_LOGGER.warning(
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"Audio stream not found"
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) # Some streams declare an audio stream and never send any packets
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audio_stream = None
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except (av.AVError, StopIteration) as ex:
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_LOGGER.error(
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"Error demuxing stream while finding first packet: %s", str(ex)
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)
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return False
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return True
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if not peek_first_pts():
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container.close()
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return
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segment_buffer.set_streams(video_stream, audio_stream)
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segment_buffer.reset(segment_start_pts)
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while not quit_event.is_set():
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try:
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if len(initial_packets) > 0:
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packet = initial_packets.popleft()
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else:
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packet = next(container_packets)
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if packet.dts is None:
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# Allow MAX_MISSING_DTS consecutive packets without dts. Terminate the stream on the next one.
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if missing_dts >= MAX_MISSING_DTS:
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raise StopIteration(
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f"No dts in {MAX_MISSING_DTS+1} consecutive packets"
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)
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missing_dts += 1
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continue
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missing_dts = 0
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except (av.AVError, StopIteration) as ex:
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_LOGGER.error("Error demuxing stream: %s", str(ex))
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break
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# Discard packet if dts is not monotonic
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if packet.dts <= last_dts[packet.stream]:
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if (
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packet.time_base * (last_dts[packet.stream] - packet.dts)
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> MAX_TIMESTAMP_GAP
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):
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_LOGGER.warning(
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"Timestamp overflow detected: last dts %s, dts = %s, resetting stream",
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last_dts[packet.stream],
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packet.dts,
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)
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break
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continue
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# Update last_dts processed
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last_dts[packet.stream] = packet.dts
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# Mux packets, and possibly write a segment to the output stream.
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# This mutates packet timestamps and stream
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segment_buffer.mux_packet(packet)
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# Close stream
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segment_buffer.close()
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container.close()
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