"""Provides the worker thread needed for processing streams."""
from collections import deque
import io
import logging
import av
from .const import (
MAX_MISSING_DTS,
MAX_TIMESTAMP_GAP,
MIN_SEGMENT_DURATION,
PACKETS_TO_WAIT_FOR_AUDIO,
STREAM_TIMEOUT,
)
from .core import Segment, StreamBuffer
_LOGGER = logging.getLogger(__name__)
def create_stream_buffer(stream_output, video_stream, audio_stream, sequence):
"""Create a new StreamBuffer."""
segment = io.BytesIO()
container_options = (
stream_output.container_options(sequence)
if stream_output.container_options
else {}
)
output = av.open(
segment,
mode="w",
format=stream_output.format,
container_options={
"video_track_timescale": str(int(1 / video_stream.time_base)),
**container_options,
},
)
vstream = output.add_stream(template=video_stream)
# Check if audio is requested
astream = None
if audio_stream and audio_stream.name in stream_output.audio_codecs:
astream = output.add_stream(template=audio_stream)
return StreamBuffer(segment, output, vstream, astream)
def stream_worker(hass, stream, quit_event):
"""Handle consuming streams."""
try:
container = av.open(
stream.source, options=stream.options, timeout=STREAM_TIMEOUT
)
except av.AVError:
_LOGGER.error("Error opening stream %s", stream.source)
return
try:
video_stream = container.streams.video[0]
except (KeyError, IndexError):
_LOGGER.error("Stream has no video")
container.close()
return
try:
audio_stream = container.streams.audio[0]
except (KeyError, IndexError):
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
# Iterator for demuxing
container_packets = None
# The decoder timestamps of the latest packet in each stream we processed
last_dts = {video_stream: float("-inf"), audio_stream: float("-inf")}
# Keep track of consecutive packets without a dts to detect end of stream.
missing_dts = 0
# Holds the buffers for each stream provider
outputs = None
# Keep track of the number of segments we've processed
sequence = 0
# The video pts at the beginning of the segment
segment_start_pts = None
# Because of problems 1 and 2 below, we need to store the first few packets and replay them
initial_packets = deque()
# 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
def peek_first_pts():
"""Initialize by peeking into the first few packets of the stream.
Deal with problem #1 above (bad first packet pts/dts) by recalculating using pts/dts from second packet.
Also load the first video keyframe pts into segment_start_pts and check if the audio stream really exists.
"""
nonlocal segment_start_pts, audio_stream, container_packets
missing_dts = 0
found_audio = False
try:
container_packets = container.demux((video_stream, audio_stream))
first_packet = None
# Get to first video keyframe
while first_packet is None:
packet = next(container_packets)
if (
packet.dts is None
): # Allow MAX_MISSING_DTS packets with no dts, raise error on the next one
if missing_dts >= MAX_MISSING_DTS:
raise StopIteration(
f"Invalid data - got {MAX_MISSING_DTS+1} packets with missing DTS while initializing"
)
missing_dts += 1
continue
if packet.stream == audio_stream:
found_audio = True
elif packet.is_keyframe: # video_keyframe
first_packet = packet
initial_packets.append(packet)
# Get first_pts from subsequent frame to first keyframe
while segment_start_pts is None or (
audio_stream
and not found_audio
and len(initial_packets) < PACKETS_TO_WAIT_FOR_AUDIO
):
packet = next(container_packets)
if (
packet.dts is None
): # Allow MAX_MISSING_DTS packet with no dts, raise error on the next one
if missing_dts >= MAX_MISSING_DTS:
raise StopIteration(
f"Invalid data - got {MAX_MISSING_DTS+1} packets with missing DTS while initializing"
)
missing_dts += 1
continue
if packet.stream == audio_stream:
found_audio = True
elif (
segment_start_pts is None
): # This is the second video frame to calculate first_pts from
segment_start_pts = packet.dts - packet.duration
first_packet.pts = segment_start_pts
first_packet.dts = segment_start_pts
initial_packets.append(packet)
if audio_stream and not found_audio:
_LOGGER.warning(
"Audio stream not found"
) # Some streams declare an audio stream and never send any packets
audio_stream = None
except (av.AVError, StopIteration) as ex:
_LOGGER.error(
"Error demuxing stream while finding first packet: %s", str(ex)
)
return False
return True
def initialize_segment(video_pts):
"""Reset some variables and initialize outputs for each segment."""
nonlocal outputs, sequence, segment_start_pts
# Clear outputs and increment sequence
outputs = {}
sequence += 1
segment_start_pts = video_pts
for stream_output in stream.outputs.values():
if video_stream.name not in stream_output.video_codecs:
continue
buffer = create_stream_buffer(
stream_output, video_stream, audio_stream, sequence
)
outputs[stream_output.name] = (
buffer,
{video_stream: buffer.vstream, audio_stream: buffer.astream},
)
def mux_video_packet(packet):
# mux packets to each buffer
for buffer, output_streams in outputs.values():
# Assign the packet to the new stream & mux
packet.stream = output_streams[video_stream]
buffer.output.mux(packet)
def mux_audio_packet(packet):
# almost the same as muxing video but add extra check
for buffer, output_streams in outputs.values():
# Assign the packet to the new stream & mux
if output_streams.get(audio_stream):
packet.stream = output_streams[audio_stream]
buffer.output.mux(packet)
if not peek_first_pts():
container.close()
return
initialize_segment(segment_start_pts)
while not quit_event.is_set():
try:
if len(initial_packets) > 0:
packet = initial_packets.popleft()
else:
packet = next(container_packets)
if packet.dts is None:
# Allow MAX_MISSING_DTS consecutive packets without dts. Terminate the stream on the next one.
if missing_dts >= MAX_MISSING_DTS:
raise StopIteration(
f"No dts in {MAX_MISSING_DTS+1} consecutive packets"
)
missing_dts += 1
continue
missing_dts = 0
except (av.AVError, StopIteration) as ex:
_LOGGER.error("Error demuxing stream: %s", str(ex))
break
# Discard packet if dts is not monotonic
if packet.dts <= last_dts[packet.stream]:
if (
packet.time_base * (last_dts[packet.stream] - packet.dts)
> MAX_TIMESTAMP_GAP
):
_LOGGER.warning(
"Timestamp overflow detected: last dts %s, dts = %s, resetting stream",
last_dts[packet.stream],
packet.dts,
)
break
continue
# Check for end of segment
if packet.stream == video_stream and packet.is_keyframe:
segment_duration = (packet.pts - segment_start_pts) * packet.time_base
if segment_duration >= MIN_SEGMENT_DURATION:
# Save segment to outputs
for fmt, (buffer, _) in outputs.items():
buffer.output.close()
if stream.outputs.get(fmt):
stream.outputs[fmt].put(
Segment(
sequence,
buffer.segment,
segment_duration,
),
)
# Reinitialize
initialize_segment(packet.pts)
# Update last_dts processed
last_dts[packet.stream] = packet.dts
# mux packets
if packet.stream == video_stream:
mux_video_packet(packet) # mutates packet timestamps
else:
mux_audio_packet(packet) # mutates packet timestamps
# Close stream
for buffer, _ in outputs.values():
buffer.output.close()
container.close()