""" OpenWebRX csdr plugin: do the signal processing with csdr This file is part of OpenWebRX, an open-source SDR receiver software with a web UI. Copyright (c) 2013-2015 by Andras Retzler Copyright (c) 2019-2020 by Jakob Ketterl This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see . """ import subprocess import os import signal import threading import math from functools import partial from owrx.kiss import KissClient, DirewolfConfig from owrx.wsjt import Ft8Chopper, WsprChopper, Jt9Chopper, Jt65Chopper, Ft4Chopper import logging logger = logging.getLogger(__name__) class output(object): def send_output(self, t, read_fn): if not self.supports_type(t): # TODO rewrite the output mechanism in a way that avoids producing unnecessary data logger.warning("dumping output of type %s since it is not supported.", t) threading.Thread(target=self.pump(read_fn, lambda x: None)).start() return self.receive_output(t, read_fn) def receive_output(self, t, read_fn): pass def pump(self, read, write): def copy(): run = True while run: data = read() if data is None or (isinstance(data, bytes) and len(data) == 0): run = False else: write(data) return copy def supports_type(self, t): return True class dsp(object): def __init__(self, output): self.samp_rate = 250000 self.output_rate = 11025 self.fft_size = 1024 self.fft_fps = 5 self.offset_freq = 0 self.low_cut = -4000 self.high_cut = 4000 self.bpf_transition_bw = 320 # Hz, and this is a constant self.ddc_transition_bw_rate = 0.15 # of the IF sample rate self.running = False self.secondary_processes_running = False self.audio_compression = "none" self.fft_compression = "none" self.demodulator = "nfm" self.name = "csdr" self.base_bufsize = 512 self.nc_port = None self.csdr_dynamic_bufsize = False self.csdr_print_bufsizes = False self.csdr_through = False self.squelch_level = -150 self.fft_averages = 50 self.iqtee = False self.iqtee2 = False self.secondary_demodulator = None self.secondary_fft_size = 1024 self.secondary_process_fft = None self.secondary_process_demod = None self.pipe_names = [ "bpf_pipe", "shift_pipe", "squelch_pipe", "smeter_pipe", "meta_pipe", "iqtee_pipe", "iqtee2_pipe", "dmr_control_pipe", ] self.pipes = {} self.pipe_files = {} self.secondary_pipe_names = ["secondary_shift_pipe"] self.secondary_offset_freq = 1000 self.unvoiced_quality = 1 self.modification_lock = threading.Lock() self.output = output self.temporary_directory = None self.pipe_base_path = None self.set_temporary_directory("/tmp") self.is_service = False self.direwolf_config = None self.direwolf_port = None self.process = None def set_service(self, flag=True): self.is_service = flag def set_temporary_directory(self, what): self.temporary_directory = what self.pipe_base_path = "{tmp_dir}/openwebrx_pipe_{myid}_".format(tmp_dir=self.temporary_directory, myid=id(self)) def chain(self, which): chain = ["nc -v 127.0.0.1 {nc_port}"] if self.csdr_dynamic_bufsize: chain += ["csdr setbuf {start_bufsize}"] if self.csdr_through: chain += ["csdr through"] if which == "fft": chain += [ "csdr fft_cc {fft_size} {fft_block_size}", "csdr logpower_cf -70" if self.fft_averages == 0 else "csdr logaveragepower_cf -70 {fft_size} {fft_averages}", "csdr fft_exchange_sides_ff {fft_size}", ] if self.fft_compression == "adpcm": chain += ["csdr compress_fft_adpcm_f_u8 {fft_size}"] return chain chain += ["csdr shift_addition_cc --fifo {shift_pipe}"] if self.decimation > 1: chain += ["csdr fir_decimate_cc {decimation} {ddc_transition_bw} HAMMING"] chain += ["csdr bandpass_fir_fft_cc --fifo {bpf_pipe} {bpf_transition_bw} HAMMING"] if self.output.supports_type("smeter"): chain += [ "csdr squelch_and_smeter_cc --fifo {squelch_pipe} --outfifo {smeter_pipe} 5 {smeter_report_every}" ] if self.secondary_demodulator: if self.output.supports_type("secondary_fft"): chain += ["csdr tee {iqtee_pipe}"] chain += ["csdr tee {iqtee2_pipe}"] # early exit if we don't want audio if not self.output.supports_type("audio"): return chain # safe some cpu cycles... no need to decimate if decimation factor is 1 last_decimation_block = ( ["csdr fractional_decimator_ff {last_decimation}"] if self.last_decimation != 1.0 else [] ) if which == "nfm": chain += ["csdr fmdemod_quadri_cf", "csdr limit_ff"] chain += last_decimation_block chain += ["csdr deemphasis_nfm_ff {audio_rate}"] if self.get_audio_rate() != self.get_output_rate(): chain += [ "sox -t raw -r {audio_rate} -e floating-point -b 32 -c 1 --buffer 32 - -t raw -r {output_rate} -e signed-integer -b 16 -c 1 - " ] else: chain += ["csdr convert_f_s16"] elif self.isDigitalVoice(which): chain += ["csdr fmdemod_quadri_cf", "dc_block "] chain += last_decimation_block # dsd modes if which in ["dstar", "nxdn"]: chain += ["csdr limit_ff", "csdr convert_f_s16"] if which == "dstar": chain += ["dsd -fd -i - -o - -u {unvoiced_quality} -g -1 "] elif which == "nxdn": chain += ["dsd -fi -i - -o - -u {unvoiced_quality} -g -1 "] chain += ["CSDR_FIXED_BUFSIZE=32 csdr convert_s16_f"] max_gain = 5 # digiham modes else: chain += ["rrc_filter", "gfsk_demodulator"] if which == "dmr": chain += [ "dmr_decoder --fifo {meta_pipe} --control-fifo {dmr_control_pipe}", "mbe_synthesizer -f -u {unvoiced_quality}", ] elif which == "ysf": chain += ["ysf_decoder --fifo {meta_pipe}", "mbe_synthesizer -y -f -u {unvoiced_quality}"] max_gain = 0.0005 chain += [ "digitalvoice_filter -f", "CSDR_FIXED_BUFSIZE=32 csdr agc_ff 160000 0.8 1 0.0000001 {max_gain}".format(max_gain=max_gain), "sox -t raw -r 8000 -e floating-point -b 32 -c 1 --buffer 32 - -t raw -r {output_rate} -e signed-integer -b 16 -c 1 - ", ] elif which == "am": chain += ["csdr amdemod_cf", "csdr fastdcblock_ff"] chain += last_decimation_block chain += ["csdr agc_ff", "csdr limit_ff", "csdr convert_f_s16"] elif which == "ssb": chain += ["csdr realpart_cf"] chain += last_decimation_block chain += ["csdr agc_ff", "csdr limit_ff"] # fixed sample rate necessary for the wsjt-x tools. fix with sox... if self.get_audio_rate() != self.get_output_rate(): chain += [ "sox -t raw -r {audio_rate} -e floating-point -b 32 -c 1 --buffer 32 - -t raw -r {output_rate} -e signed-integer -b 16 -c 1 - " ] else: chain += ["csdr convert_f_s16"] if self.audio_compression == "adpcm": chain += ["csdr encode_ima_adpcm_i16_u8"] return chain def secondary_chain(self, which): chain = ["cat {input_pipe}"] if which == "fft": chain += [ "csdr realpart_cf", "csdr fft_fc {secondary_fft_input_size} {secondary_fft_block_size}", "csdr logpower_cf -70", ] if self.fft_compression == "adpcm": chain += ["csdr compress_fft_adpcm_f_u8 {secondary_fft_size}"] return chain elif which == "bpsk31" or which == "bpsk63": return chain + [ "csdr shift_addition_cc --fifo {secondary_shift_pipe}", "csdr bandpass_fir_fft_cc -{secondary_bpf_cutoff} {secondary_bpf_cutoff} {secondary_bpf_cutoff}", "csdr simple_agc_cc 0.001 0.5", "csdr timing_recovery_cc GARDNER {secondary_samples_per_bits} 0.5 2 --add_q", "CSDR_FIXED_BUFSIZE=1 csdr dbpsk_decoder_c_u8", "CSDR_FIXED_BUFSIZE=1 csdr psk31_varicode_decoder_u8_u8", ] elif self.isWsjtMode(which): chain += ["csdr realpart_cf"] if self.last_decimation != 1.0: chain += ["csdr fractional_decimator_ff {last_decimation}"] return chain + ["csdr limit_ff", "csdr convert_f_s16"] elif which == "packet": chain += ["csdr fmdemod_quadri_cf"] if self.last_decimation != 1.0: chain += ["csdr fractional_decimator_ff {last_decimation}"] return chain + ["csdr convert_f_s16", "direwolf -c {direwolf_config} -r {audio_rate} -t 0 -q d -q h 1>&2"] elif which == "pocsag": chain += ["csdr fmdemod_quadri_cf"] if self.last_decimation != 1.0: chain += ["csdr fractional_decimator_ff {last_decimation}"] return chain + ["fsk_demodulator -i", "pocsag_decoder"] def set_secondary_demodulator(self, what): if self.get_secondary_demodulator() == what: return self.secondary_demodulator = what self.calculate_decimation() self.restart() def secondary_fft_block_size(self): return (self.samp_rate / self.decimation) / ( self.fft_fps * 2 ) # *2 is there because we do FFT on real signal here def secondary_decimation(self): return 1 # currently unused def secondary_bpf_cutoff(self): if self.secondary_demodulator == "bpsk31": return 31.25 / self.if_samp_rate() elif self.secondary_demodulator == "bpsk63": return 62.5 / self.if_samp_rate() return 0 def secondary_bpf_transition_bw(self): if self.secondary_demodulator == "bpsk31": return 31.25 / self.if_samp_rate() elif self.secondary_demodulator == "bpsk63": return 62.5 / self.if_samp_rate() return 0 def secondary_samples_per_bits(self): if self.secondary_demodulator == "bpsk31": return int(round(self.if_samp_rate() / 31.25)) & ~3 elif self.secondary_demodulator == "bpsk63": return int(round(self.if_samp_rate() / 62.5)) & ~3 return 0 def secondary_bw(self): if self.secondary_demodulator == "bpsk31": return 31.25 elif self.secondary_demodulator == "bpsk63": return 62.5 def start_secondary_demodulator(self): if not self.secondary_demodulator: return logger.debug("starting secondary demodulator from IF input sampled at %d" % self.if_samp_rate()) secondary_command_demod = " | ".join(self.secondary_chain(self.secondary_demodulator)) self.try_create_pipes(self.secondary_pipe_names, secondary_command_demod) self.try_create_configs(secondary_command_demod) secondary_command_demod = secondary_command_demod.format( input_pipe=self.pipes["iqtee2_pipe"], secondary_shift_pipe=self.pipes["secondary_shift_pipe"], secondary_decimation=self.secondary_decimation(), secondary_samples_per_bits=self.secondary_samples_per_bits(), secondary_bpf_cutoff=self.secondary_bpf_cutoff(), secondary_bpf_transition_bw=self.secondary_bpf_transition_bw(), if_samp_rate=self.if_samp_rate(), last_decimation=self.last_decimation, audio_rate=self.get_audio_rate(), direwolf_config=self.direwolf_config, ) logger.debug("secondary command (demod) = %s", secondary_command_demod) my_env = os.environ.copy() # if self.csdr_dynamic_bufsize: my_env["CSDR_DYNAMIC_BUFSIZE_ON"]="1"; if self.csdr_print_bufsizes: my_env["CSDR_PRINT_BUFSIZES"] = "1" if self.output.supports_type("secondary_fft"): secondary_command_fft = " | ".join(self.secondary_chain("fft")) secondary_command_fft = secondary_command_fft.format( input_pipe=self.pipes["iqtee_pipe"], secondary_fft_input_size=self.secondary_fft_size, secondary_fft_size=self.secondary_fft_size, secondary_fft_block_size=self.secondary_fft_block_size(), ) logger.debug("secondary command (fft) = %s", secondary_command_fft) self.secondary_process_fft = subprocess.Popen( secondary_command_fft, stdout=subprocess.PIPE, shell=True, start_new_session=True, env=my_env ) self.output.send_output( "secondary_fft", partial(self.secondary_process_fft.stdout.read, int(self.get_secondary_fft_bytes_to_read())), ) # direwolf does not provide any meaningful data on stdout # more specifically, it doesn't provide any data. if however, for any strange reason, it would start to do so, # it would block if not read. by piping it to devnull, we avoid a potential pitfall here. secondary_output = subprocess.DEVNULL if self.isPacket() else subprocess.PIPE self.secondary_process_demod = subprocess.Popen( secondary_command_demod, stdout=secondary_output, shell=True, start_new_session=True, env=my_env ) self.secondary_processes_running = True if self.isWsjtMode(): smd = self.get_secondary_demodulator() chopper = None if smd == "ft8": chopper = Ft8Chopper(self.secondary_process_demod.stdout) elif smd == "wspr": chopper = WsprChopper(self.secondary_process_demod.stdout) elif smd == "jt65": chopper = Jt65Chopper(self.secondary_process_demod.stdout) elif smd == "jt9": chopper = Jt9Chopper(self.secondary_process_demod.stdout) elif smd == "ft4": chopper = Ft4Chopper(self.secondary_process_demod.stdout) if chopper is not None: chopper.start() self.output.send_output("wsjt_demod", chopper.read) elif self.isPacket(): # we best get the ax25 packets from the kiss socket kiss = KissClient(self.direwolf_port) self.output.send_output("packet_demod", kiss.read) elif self.isPocsag(): self.output.send_output("pocsag_demod", self.secondary_process_demod.stdout.readline) else: self.output.send_output("secondary_demod", partial(self.secondary_process_demod.stdout.read, 1)) # open control pipes for csdr and send initialization data if self.has_pipe("secondary_shift_pipe"): # TODO digimodes self.pipe_files["secondary_shift_pipe"] = open(self.pipes["secondary_shift_pipe"], "w") # TODO digimodes self.set_secondary_offset_freq(self.secondary_offset_freq) # TODO digimodes def set_secondary_offset_freq(self, value): self.secondary_offset_freq = value if self.secondary_processes_running and self.has_pipe("secondary_shift_pipe"): self.pipe_files["secondary_shift_pipe"].write("%g\n" % (-float(self.secondary_offset_freq) / self.if_samp_rate())) self.pipe_files["secondary_shift_pipe"].flush() def stop_secondary_demodulator(self): if not self.secondary_processes_running: return self.try_delete_pipes(self.secondary_pipe_names) self.try_delete_configs() if self.secondary_process_fft: try: os.killpg(os.getpgid(self.secondary_process_fft.pid), signal.SIGTERM) except ProcessLookupError: # been killed by something else, ignore pass if self.secondary_process_demod: try: os.killpg(os.getpgid(self.secondary_process_demod.pid), signal.SIGTERM) except ProcessLookupError: # been killed by something else, ignore pass self.secondary_processes_running = False def get_secondary_demodulator(self): return self.secondary_demodulator def set_secondary_fft_size(self, secondary_fft_size): # to change this, restart is required self.secondary_fft_size = secondary_fft_size def set_audio_compression(self, what): self.audio_compression = what def get_audio_bytes_to_read(self): # desired latency: 5ms # uncompressed audio has 16 bits = 2 bytes per sample base = self.output_rate * 0.005 * 2 # adpcm compresses the bitstream by 4 if self.audio_compression == "adpcm": base = base / 4 return int(base) def set_fft_compression(self, what): self.fft_compression = what def get_fft_bytes_to_read(self): if self.fft_compression == "none": return self.fft_size * 4 if self.fft_compression == "adpcm": return int((self.fft_size / 2) + (10 / 2)) def get_secondary_fft_bytes_to_read(self): if self.fft_compression == "none": return self.secondary_fft_size * 4 if self.fft_compression == "adpcm": return (self.secondary_fft_size / 2) + (10 / 2) def set_samp_rate(self, samp_rate): self.samp_rate = samp_rate self.calculate_decimation() if self.running: self.restart() def calculate_decimation(self): (self.decimation, self.last_decimation, _) = self.get_decimation(self.samp_rate, self.get_audio_rate()) def get_decimation(self, input_rate, output_rate): decimation = 1 while input_rate / (decimation + 1) >= output_rate: decimation += 1 fraction = float(input_rate / decimation) / output_rate intermediate_rate = input_rate / decimation return decimation, fraction, intermediate_rate def if_samp_rate(self): return self.samp_rate / self.decimation def get_name(self): return self.name def get_output_rate(self): return self.output_rate def get_audio_rate(self): if self.isDigitalVoice() or self.isPacket() or self.isPocsag(): return 48000 elif self.isWsjtMode(): return 12000 return self.get_output_rate() def isDigitalVoice(self, demodulator=None): if demodulator is None: demodulator = self.get_demodulator() return demodulator in ["dmr", "dstar", "nxdn", "ysf"] def isWsjtMode(self, demodulator=None): if demodulator is None: demodulator = self.get_secondary_demodulator() return demodulator in ["ft8", "wspr", "jt65", "jt9", "ft4"] def isPacket(self, demodulator=None): if demodulator is None: demodulator = self.get_secondary_demodulator() return demodulator == "packet" def isPocsag(self, demodulator=None): if demodulator is None: demodulator = self.get_secondary_demodulator() return demodulator == "pocsag" def set_output_rate(self, output_rate): if self.output_rate == output_rate: return self.output_rate = output_rate self.calculate_decimation() self.restart() def set_demodulator(self, demodulator): if self.demodulator == demodulator: return self.demodulator = demodulator self.calculate_decimation() self.restart() def get_demodulator(self): return self.demodulator def set_fft_size(self, fft_size): self.fft_size = fft_size self.restart() def set_fft_fps(self, fft_fps): self.fft_fps = fft_fps self.restart() def set_fft_averages(self, fft_averages): self.fft_averages = fft_averages self.restart() def fft_block_size(self): if self.fft_averages == 0: return self.samp_rate / self.fft_fps else: return self.samp_rate / self.fft_fps / self.fft_averages def set_offset_freq(self, offset_freq): self.offset_freq = offset_freq if self.running: with self.modification_lock: self.pipe_files["shift_pipe"].write("%g\n" % (-float(self.offset_freq) / self.samp_rate)) self.pipe_files["shift_pipe"].flush() def set_bpf(self, low_cut, high_cut): self.low_cut = low_cut self.high_cut = high_cut if self.running: with self.modification_lock: self.pipe_files["bpf_pipe"].write( "%g %g\n" % (float(self.low_cut) / self.if_samp_rate(), float(self.high_cut) / self.if_samp_rate()) ) self.pipe_files["bpf_pipe"].flush() def get_bpf(self): return [self.low_cut, self.high_cut] def convertToLinear(self, db): return float(math.pow(10, db / 10)) def set_squelch_level(self, squelch_level): self.squelch_level = squelch_level # no squelch required on digital voice modes actual_squelch = -150 if self.isDigitalVoice() or self.isPacket() or self.isPocsag() else self.squelch_level if self.running: with self.modification_lock: self.pipe_files["squelch_pipe"].write("%g\n" % (self.convertToLinear(actual_squelch))) self.pipe_files["squelch_pipe"].flush() def set_unvoiced_quality(self, q): self.unvoiced_quality = q self.restart() def get_unvoiced_quality(self): return self.unvoiced_quality def set_dmr_filter(self, filter): if self.has_pipe("dmr_control_pipe"): self.pipe_files["dmr_control_pipe"].write("{0}\n".format(filter)) self.pipe_files["dmr_control_pipe"].flush() def mkfifo(self, path): try: os.unlink(path) except: pass os.mkfifo(path) def ddc_transition_bw(self): return self.ddc_transition_bw_rate * (self.if_samp_rate() / float(self.samp_rate)) def try_create_pipes(self, pipe_names, command_base): for pipe_name in pipe_names: if "{" + pipe_name + "}" in command_base: p = self.pipe_base_path + pipe_name self.pipes[pipe_name] = p self.mkfifo(p) else: self.pipes[pipe_name] = None def has_pipe(self, name): return name in self.pipes and self.pipes[name] is not None def try_delete_pipes(self, pipe_names): for pipe_name in pipe_names: if self.has_pipe(pipe_name): pipe_path = self.pipes[pipe_name] try: os.unlink(pipe_path) except FileNotFoundError: # it seems like we keep calling this twice. no idea why, but we don't need the resulting error. pass except Exception: logger.exception("try_delete_pipes()") finally: self.pipes[pipe_name] = None def try_create_configs(self, command): if "{direwolf_config}" in command: self.direwolf_config = "{tmp_dir}/openwebrx_direwolf_{myid}.conf".format( tmp_dir=self.temporary_directory, myid=id(self) ) self.direwolf_port = KissClient.getFreePort() file = open(self.direwolf_config, "w") file.write(DirewolfConfig().getConfig(self.direwolf_port, self.is_service)) file.close() else: self.direwolf_config = None self.direwolf_port = None def try_delete_configs(self): if self.direwolf_config: try: os.unlink(self.direwolf_config) except FileNotFoundError: # result suits our expectations. fine :) pass except Exception: logger.exception("try_delete_configs()") self.direwolf_config = None def start(self): with self.modification_lock: if self.running: return self.running = True command_base = " | ".join(self.chain(self.demodulator)) # create control pipes for csdr self.try_create_pipes(self.pipe_names, command_base) # run the command command = command_base.format( bpf_pipe=self.pipes["bpf_pipe"], shift_pipe=self.pipes["shift_pipe"], squelch_pipe=self.pipes["squelch_pipe"], smeter_pipe=self.pipes["smeter_pipe"], meta_pipe=self.pipes["meta_pipe"], iqtee_pipe=self.pipes["iqtee_pipe"], iqtee2_pipe=self.pipes["iqtee2_pipe"], dmr_control_pipe=self.pipes["dmr_control_pipe"], decimation=self.decimation, last_decimation=self.last_decimation, fft_size=self.fft_size, fft_block_size=self.fft_block_size(), fft_averages=self.fft_averages, bpf_transition_bw=float(self.bpf_transition_bw) / self.if_samp_rate(), ddc_transition_bw=self.ddc_transition_bw(), flowcontrol=int(self.samp_rate * 2), start_bufsize=self.base_bufsize * self.decimation, nc_port=self.nc_port, output_rate=self.get_output_rate(), smeter_report_every=int(self.if_samp_rate() / 6000), unvoiced_quality=self.get_unvoiced_quality(), audio_rate=self.get_audio_rate(), ) logger.debug("Command = %s", command) my_env = os.environ.copy() if self.csdr_dynamic_bufsize: my_env["CSDR_DYNAMIC_BUFSIZE_ON"] = "1" if self.csdr_print_bufsizes: my_env["CSDR_PRINT_BUFSIZES"] = "1" out = subprocess.PIPE if self.output.supports_type("audio") else subprocess.DEVNULL self.process = subprocess.Popen(command, stdout=out, shell=True, start_new_session=True, env=my_env) def watch_thread(): rc = self.process.wait() logger.debug("dsp thread ended with rc=%d", rc) if rc == 0 and self.running and not self.modification_lock.locked(): logger.debug("restarting since rc = 0, self.running = true, and no modification") self.restart() threading.Thread(target=watch_thread).start() if self.output.supports_type("audio"): self.output.send_output( "audio", partial( self.process.stdout.read, self.get_fft_bytes_to_read() if self.demodulator == "fft" else self.get_audio_bytes_to_read(), ), ) self.start_secondary_demodulator() # open control pipes for csdr for p in ["bpf_pipe", "shift_pipe", "squelch_pipe", "dmr_control_pipe"]: if self.has_pipe(p): self.pipe_files[p] = open(self.pipes[p], "w") # send initial config through the pipes if self.has_pipe("squelch_pipe"): self.set_squelch_level(self.squelch_level) if self.has_pipe("shift_pipe"): self.set_offset_freq(self.offset_freq) if self.has_pipe("bpf_pipe"): self.set_bpf(self.low_cut, self.high_cut) if self.has_pipe("smeter_pipe"): self.pipe_files["smeter_pipe"] = open(self.pipes["smeter_pipe"], "r") def read_smeter(): raw = self.pipe_files["smeter_pipe"].readline() if len(raw) == 0: return None else: return float(raw.rstrip("\n")) self.output.send_output("smeter", read_smeter) if self.has_pipe("meta_pipe"): # TODO make digiham output unicode and then change this here self.pipe_files["meta_pipe"] = open(self.pipes["meta_pipe"], "r", encoding="cp437") def read_meta(): raw = self.pipe_files["meta_pipe"].readline() if len(raw) == 0: return None else: return raw.rstrip("\n") self.output.send_output("meta", read_meta) def stop(self): with self.modification_lock: self.running = False if self.process is not None: try: os.killpg(os.getpgid(self.process.pid), signal.SIGTERM) self.process = None except ProcessLookupError: # been killed by something else, ignore pass self.stop_secondary_demodulator() self.try_delete_pipes(self.pipe_names) def restart(self): if not self.running: return self.stop() self.start() def __del__(self): self.stop()