openwebrx-clone/owrx/dsp.py

from owrx.source import SdrSourceEventClient, SdrSourceState, SdrClientClass
from owrx.property import PropertyStack, PropertyLayer, PropertyValidator
from owrx.property.validators import OrValidator, RegexValidator, BoolValidator
from owrx.modes import Modes, DigitalMode
from csdr.chain import Chain
from csdr.chain.demodulator import BaseDemodulatorChain, FixedIfSampleRateChain, FixedAudioRateChain, HdAudio, SecondaryDemodulator, DialFrequencyReceiver, MetaProvider, SlotFilterChain, SecondarySelectorChain, DeemphasisTauChain, DemodulatorError
from csdr.chain.selector import Selector, SecondarySelector
from csdr.chain.clientaudio import ClientAudioChain
from csdr.chain.fft import FftChain
from csdr.chain.dummy import DummyDemodulator
from pycsdr.modules import Buffer, Writer
from pycsdr.types import Format
from typing import Union, Optional
from io import BytesIO
from abc import ABC, abstractmethod
import threading
import re
import pickle

import logging

logger = logging.getLogger(__name__)


# now that's a name. help, i've reached enterprise level OOP here
class ClientDemodulatorSecondaryDspEventClient(ABC):
    @abstractmethod
    def onSecondaryDspRateChange(self, rate):
        pass

    @abstractmethod
    def onSecondaryDspBandwidthChange(self, bw):
        pass


class ClientDemodulatorChain(Chain):
    def __init__(self, demod: BaseDemodulatorChain, sampleRate: int, outputRate: int, hdOutputRate: int, audioCompression: str, secondaryDspEventReceiver: ClientDemodulatorSecondaryDspEventClient):
        self.sampleRate = sampleRate
        self.outputRate = outputRate
        self.hdOutputRate = hdOutputRate
        self.secondaryDspEventReceiver = secondaryDspEventReceiver
        self.selector = Selector(sampleRate, outputRate)
        self.selector.setBandpass(-4000, 4000)
        self.selectorBuffer = Buffer(Format.COMPLEX_FLOAT)
        self.audioBuffer = None
        self.demodulator = demod
        self.secondaryDemodulator = None
        self.centerFrequency = None
        self.frequencyOffset = None
        self.wfmDeemphasisTau = 50e-6
        inputRate = demod.getFixedAudioRate() if isinstance(demod, FixedAudioRateChain) else outputRate
        oRate = hdOutputRate if isinstance(demod, HdAudio) else outputRate
        self.clientAudioChain = ClientAudioChain(demod.getOutputFormat(), inputRate, oRate, audioCompression)
        self.secondaryFftSize = 2048
        self.secondaryFftOverlapFactor = 0.3
        self.secondaryFftFps = 9
        self.secondaryFftCompression = "adpcm"
        self.secondaryFftChain = None
        self.metaWriter = None
        self.secondaryFftWriter = None
        self.secondaryWriter = None
        self.squelchLevel = -150
        self.secondarySelector = None
        self.secondaryFrequencyOffset = None
        super().__init__([self.selector, self.demodulator, self.clientAudioChain])

    def stop(self):
        super().stop()
        if self.secondaryFftChain is not None:
            self.secondaryFftChain.stop()
            self.secondaryFftChain = None
        if self.secondaryDemodulator is not None:
            self.secondaryDemodulator.stop()
            self.secondaryDemodulator = None

    def _connect(self, w1, w2, buffer: Optional[Buffer] = None) -> None:
        if w1 is self.selector:
            super()._connect(w1, w2, self.selectorBuffer)
        elif w2 is self.clientAudioChain:
            format = w1.getOutputFormat()
            if self.audioBuffer is None or self.audioBuffer.getFormat() != format:
                self.audioBuffer = Buffer(format)
                if self.secondaryDemodulator is not None and self.secondaryDemodulator.getInputFormat() is not Format.COMPLEX_FLOAT:
                    self.secondaryDemodulator.setReader(self.audioBuffer.getReader())
            super()._connect(w1, w2, self.audioBuffer)
        else:
            super()._connect(w1, w2)

    def setDemodulator(self, demodulator: BaseDemodulatorChain):
        if demodulator is self.demodulator:
            return

        try:
            self.clientAudioChain.setFormat(demodulator.getOutputFormat())
        except ValueError:
            # this will happen if the new format does not match the current demodulator.
            # it's expected and should be mended when swapping out the demodulator in the next step
            pass

        self.replace(1, demodulator)

        if self.demodulator is not None:
            self.demodulator.stop()

        self.demodulator = demodulator

        self.selector.setOutputRate(self._getSelectorOutputRate())

        clientRate = self._getClientAudioInputRate()
        self.clientAudioChain.setInputRate(clientRate)
        self.demodulator.setSampleRate(clientRate)

        if isinstance(self.demodulator, DeemphasisTauChain):
            self.demodulator.setDeemphasisTau(self.wfmDeemphasisTau)

        self._updateDialFrequency()
        self._syncSquelch()

        outputRate = self.hdOutputRate if isinstance(self.demodulator, HdAudio) else self.outputRate
        self.clientAudioChain.setClientRate(outputRate)

        if self.metaWriter is not None and isinstance(demodulator, MetaProvider):
            demodulator.setMetaWriter(self.metaWriter)

    def stopDemodulator(self):
        if self.demodulator is None:
            return

        # we need to get the currrent demodulator out of the chain so that it can be deallocated properly
        # so we just replace it with a dummy here
        # in order to avoid any client audio chain hassle, the dummy simply imitates the output format of the current
        # demodulator
        self.replace(1, DummyDemodulator(self.demodulator.getOutputFormat()))

        self.demodulator.stop()
        self.demodulator = None

    def _getSelectorOutputRate(self):
        if isinstance(self.demodulator, FixedIfSampleRateChain):
            return self.demodulator.getFixedIfSampleRate()
        elif isinstance(self.secondaryDemodulator, FixedAudioRateChain):
            if isinstance(self.demodulator, FixedAudioRateChain) and self.demodulator.getFixedAudioRate() != self.secondaryDemodulator.getFixedAudioRate():
                raise ValueError("secondary and primary demodulator chain audio rates do not match!")
            return self.secondaryDemodulator.getFixedAudioRate()
        else:
            return self.hdOutputRate if isinstance(self.demodulator, HdAudio) else self.outputRate

    def _getClientAudioInputRate(self):
        if isinstance(self.demodulator, FixedAudioRateChain):
            return self.demodulator.getFixedAudioRate()
        elif isinstance(self.secondaryDemodulator, FixedAudioRateChain):
            return self.secondaryDemodulator.getFixedAudioRate()
        else:
            return self.hdOutputRate if isinstance(self.demodulator, HdAudio) else self.outputRate

    def setSecondaryDemodulator(self, demod: Optional[SecondaryDemodulator]):
        if demod is self.secondaryDemodulator:
            return

        if self.secondaryDemodulator is not None:
            self.secondaryDemodulator.stop()

        self.secondaryDemodulator = demod

        rate = self._getSelectorOutputRate()
        self.selector.setOutputRate(rate)

        clientRate = self._getClientAudioInputRate()
        self.clientAudioChain.setInputRate(clientRate)
        self.demodulator.setSampleRate(clientRate)

        self._updateDialFrequency()
        self._syncSquelch()

        if isinstance(self.secondaryDemodulator, SecondarySelectorChain):
            bandwidth = self.secondaryDemodulator.getBandwidth()
            self.secondarySelector = SecondarySelector(rate, bandwidth)
            self.secondarySelector.setReader(self.selectorBuffer.getReader())
            self.secondarySelector.setFrequencyOffset(self.secondaryFrequencyOffset)
            self.secondaryDspEventReceiver.onSecondaryDspBandwidthChange(bandwidth)
        else:
            self.secondarySelector = None

        if self.secondaryDemodulator is not None:
            self.secondaryDemodulator.setSampleRate(rate)
            if self.secondarySelector is not None:
                buffer = Buffer(Format.COMPLEX_FLOAT)
                self.secondarySelector.setWriter(buffer)
                self.secondaryDemodulator.setReader(buffer.getReader())
            elif self.secondaryDemodulator.getInputFormat() is Format.COMPLEX_FLOAT:
                self.secondaryDemodulator.setReader(self.selectorBuffer.getReader())
            else:
                self.secondaryDemodulator.setReader(self.audioBuffer.getReader())
            self.secondaryDemodulator.setWriter(self.secondaryWriter)

        if self.secondaryDemodulator is None and self.secondaryFftChain is not None:
            self.secondaryFftChain.stop()
            self.secondaryFftChain = None

        if self.secondaryDemodulator is not None and self.secondaryFftChain is None:
            self._createSecondaryFftChain()

        if self.secondaryFftChain is not None:
            self.secondaryFftChain.setSampleRate(rate)
            self.secondaryDspEventReceiver.onSecondaryDspRateChange(rate)

    def _createSecondaryFftChain(self):
        if self.secondaryFftChain is not None:
            self.secondaryFftChain.stop()
        self.secondaryFftChain = FftChain(self._getSelectorOutputRate(), self.secondaryFftSize, self.secondaryFftOverlapFactor, self.secondaryFftFps, self.secondaryFftCompression)
        self.secondaryFftChain.setReader(self.selectorBuffer.getReader())
        self.secondaryFftChain.setWriter(self.secondaryFftWriter)

    def _syncSquelch(self):
        if not self.demodulator.supportsSquelch() or (self.secondaryDemodulator is not None and not self.secondaryDemodulator.supportsSquelch()):
            self.selector.setSquelchLevel(-150)
        else:
            self.selector.setSquelchLevel(self.squelchLevel)

    def setLowCut(self, lowCut):
        self.selector.setLowCut(lowCut)

    def setHighCut(self, highCut):
        self.selector.setHighCut(highCut)

    def setBandpass(self, lowCut, highCut):
        self.selector.setBandpass(lowCut, highCut)

    def setFrequencyOffset(self, offset: int) -> None:
        if offset == self.frequencyOffset:
            return
        self.frequencyOffset = offset
        self.selector.setFrequencyOffset(offset)
        self._updateDialFrequency()

    def setCenterFrequency(self, frequency: int) -> None:
        if frequency == self.centerFrequency:
            return
        self.centerFrequency = frequency
        self._updateDialFrequency()

    def _updateDialFrequency(self):
        if self.centerFrequency is None or self.frequencyOffset is None:
            return
        dialFrequency = self.centerFrequency + self.frequencyOffset
        if isinstance(self.demodulator, DialFrequencyReceiver):
            self.demodulator.setDialFrequency(dialFrequency)
        if isinstance(self.secondaryDemodulator, DialFrequencyReceiver):
            self.secondaryDemodulator.setDialFrequency(dialFrequency)

    def setAudioCompression(self, compression: str) -> None:
        self.clientAudioChain.setAudioCompression(compression)

    def setSquelchLevel(self, level: float) -> None:
        if level == self.squelchLevel:
            return
        self.squelchLevel = level
        self._syncSquelch()

    def setOutputRate(self, outputRate) -> None:
        if outputRate == self.outputRate:
            return

        self.outputRate = outputRate

        if isinstance(self.demodulator, HdAudio):
            return
        self._updateDemodulatorOutputRate(outputRate)

    def setHdOutputRate(self, outputRate) -> None:
        if outputRate == self.hdOutputRate:
            return

        self.hdOutputRate = outputRate

        if not isinstance(self.demodulator, HdAudio):
            return
        self._updateDemodulatorOutputRate(outputRate)

    def _updateDemodulatorOutputRate(self, outputRate):
        if not isinstance(self.demodulator, FixedIfSampleRateChain):
            self.selector.setOutputRate(outputRate)
            self.demodulator.setSampleRate(outputRate)
            if self.secondaryDemodulator is not None:
                self.secondaryDemodulator.setSampleRate(outputRate)
        if not isinstance(self.demodulator, FixedAudioRateChain):
            self.clientAudioChain.setClientRate(outputRate)

    def setSampleRate(self, sampleRate: int) -> None:
        if sampleRate == self.sampleRate:
            return
        self.sampleRate = sampleRate
        self.selector.setInputRate(sampleRate)

    def setPowerWriter(self, writer: Writer) -> None:
        self.selector.setPowerWriter(writer)

    def setMetaWriter(self, writer: Writer) -> None:
        if writer is self.metaWriter:
            return
        self.metaWriter = writer
        if isinstance(self.demodulator, MetaProvider):
            self.demodulator.setMetaWriter(self.metaWriter)

    def setSecondaryFftWriter(self, writer: Writer) -> None:
        if writer is self.secondaryFftWriter:
            return
        self.secondaryFftWriter = writer

        if self.secondaryFftChain is not None:
            self.secondaryFftChain.setWriter(writer)

    def setSecondaryWriter(self, writer: Writer) -> None:
        if writer is self.secondaryWriter:
            return
        self.secondaryWriter = writer
        if self.secondaryDemodulator is not None:
            self.secondaryDemodulator.setWriter(writer)

    def setSlotFilter(self, filter: int) -> None:
        if not isinstance(self.demodulator, SlotFilterChain):
            return
        self.demodulator.setSlotFilter(filter)

    def setSecondaryFftSize(self, size: int) -> None:
        if size == self.secondaryFftSize:
            return
        self.secondaryFftSize = size
        if not self.secondaryFftChain:
            return
        self._createSecondaryFftChain()

    def setSecondaryFrequencyOffset(self, freq: int) -> None:
        if self.secondaryFrequencyOffset == freq:
            return
        self.secondaryFrequencyOffset = freq

        if self.secondarySelector is None:
            return
        self.secondarySelector.setFrequencyOffset(self.secondaryFrequencyOffset)

    def setSecondaryFftCompression(self, compression: str) -> None:
        if compression == self.secondaryFftCompression:
            return
        self.secondaryFftCompression = compression
        if not self.secondaryFftChain:
            return
        self.secondaryFftChain.setCompression(self.secondaryFftCompression)

    def setSecondaryFftOverlapFactor(self, overlap: float) -> None:
        if overlap == self.secondaryFftOverlapFactor:
            return
        self.secondaryFftOverlapFactor = overlap
        if not self.secondaryFftChain:
            return
        self.secondaryFftChain.setVOverlapFactor(self.secondaryFftOverlapFactor)

    def setSecondaryFftFps(self, fps: int) -> None:
        if fps == self.secondaryFftFps:
            return
        self.secondaryFftFps = fps
        if not self.secondaryFftChain:
            return
        self.secondaryFftChain.setFps(self.secondaryFftFps)

    def getSecondaryFftOutputFormat(self) -> Format:
        if self.secondaryFftCompression == "adpcm":
            return Format.CHAR
        return Format.SHORT

    def setWfmDeemphasisTau(self, tau: float) -> None:
        if tau == self.wfmDeemphasisTau:
            return
        self.wfmDeemphasisTau = tau
        if isinstance(self.demodulator, DeemphasisTauChain):
            self.demodulator.setDeemphasisTau(self.wfmDeemphasisTau)


class ModulationValidator(OrValidator):
    """
    This validator only allows alphanumeric characters and numbers, but no spaces or special characters
    """

    def __init__(self):
        super().__init__(BoolValidator(), RegexValidator(re.compile("^[a-z0-9]+$")))


class DspManager(SdrSourceEventClient, ClientDemodulatorSecondaryDspEventClient):
    def __init__(self, handler, sdrSource):
        self.handler = handler
        self.sdrSource = sdrSource

        self.props = PropertyStack()

        # current audio mode. should be "audio" or "hd_audio" depending on what demodulatur is in use.
        self.audioOutput = None

        # local demodulator properties not forwarded to the sdr
        # ensure strict validation since these can be set from the client
        # and are used to build executable commands
        validators = {
            "output_rate": "int",
            "hd_output_rate": "int",
            "squelch_level": "num",
            "secondary_mod": ModulationValidator(),
            "low_cut": "num",
            "high_cut": "num",
            "offset_freq": "int",
            "mod": ModulationValidator(),
            "secondary_offset_freq": "int",
            "dmr_filter": "int",
        }
        self.localProps = PropertyValidator(PropertyLayer().filter(*validators.keys()), validators)

        self.props.addLayer(0, self.localProps)
        # properties that we inherit from the sdr
        self.props.addLayer(
            1,
            self.sdrSource.getProps().filter(
                "audio_compression",
                "fft_compression",
                "digimodes_fft_size",
                "samp_rate",
                "center_freq",
                "start_mod",
                "start_freq",
                "wfm_deemphasis_tau",
                "digital_voice_codecserver",
            ),
        )

        # defaults for values that may not be set
        self.props.addLayer(
            2,
            PropertyLayer(
                output_rate=12000,
                hd_output_rate=48000,
                digital_voice_codecserver="",
            ).readonly()
        )

        self.chain = ClientDemodulatorChain(
            self._getDemodulator("nfm"),
            self.props["samp_rate"],
            self.props["output_rate"],
            self.props["hd_output_rate"],
            self.props["audio_compression"],
            self
        )

        self.readers = {}

        if "start_mod" in self.props:
            mode = Modes.findByModulation(self.props["start_mod"])
            if mode:
                self.setDemodulator(mode.get_modulation())
                if isinstance(mode, DigitalMode):
                    self.setSecondaryDemodulator(mode.modulation)
                if mode.bandpass:
                    bpf = [mode.bandpass.low_cut, mode.bandpass.high_cut]
                    self.chain.setBandpass(*bpf)
            else:
                # TODO modes should be mandatory
                self.setDemodulator(self.props["start_mod"])

        if "start_freq" in self.props and "center_freq" in self.props:
            self.chain.setFrequencyOffset(self.props["start_freq"] - self.props["center_freq"])
        else:
            self.chain.setFrequencyOffset(0)

        self.subscriptions = [
            self.props.wireProperty("audio_compression", self.setAudioCompression),
            self.props.wireProperty("fft_compression", self.chain.setSecondaryFftCompression),
            self.props.wireProperty("fft_voverlap_factor", self.chain.setSecondaryFftOverlapFactor),
            self.props.wireProperty("fft_fps", self.chain.setSecondaryFftFps),
            self.props.wireProperty("digimodes_fft_size", self.setSecondaryFftSize),
            self.props.wireProperty("samp_rate", self.chain.setSampleRate),
            self.props.wireProperty("output_rate", self.chain.setOutputRate),
            self.props.wireProperty("hd_output_rate", self.chain.setHdOutputRate),
            self.props.wireProperty("offset_freq", self.chain.setFrequencyOffset),
            self.props.wireProperty("center_freq", self.chain.setCenterFrequency),
            self.props.wireProperty("squelch_level", self.chain.setSquelchLevel),
            self.props.wireProperty("low_cut", self.chain.setLowCut),
            self.props.wireProperty("high_cut", self.chain.setHighCut),
            self.props.wireProperty("mod", self.setDemodulator),
            self.props.wireProperty("dmr_filter", self.chain.setSlotFilter),
            self.props.wireProperty("wfm_deemphasis_tau", self.chain.setWfmDeemphasisTau),
            self.props.wireProperty("secondary_mod", self.setSecondaryDemodulator),
            self.props.wireProperty("secondary_offset_freq", self.chain.setSecondaryFrequencyOffset),
        ]

        # wire power level output
        buffer = Buffer(Format.FLOAT)
        self.chain.setPowerWriter(buffer)
        self.wireOutput("smeter", buffer)

        # wire meta output
        buffer = Buffer(Format.CHAR)
        self.chain.setMetaWriter(buffer)
        self.wireOutput("meta", buffer)

        # wire secondary FFT
        buffer = Buffer(self.chain.getSecondaryFftOutputFormat())
        self.chain.setSecondaryFftWriter(buffer)
        self.wireOutput("secondary_fft", buffer)

        # wire secondary demodulator
        buffer = Buffer(Format.CHAR)
        self.chain.setSecondaryWriter(buffer)
        self.wireOutput("secondary_demod", buffer)

        self.startOnAvailable = False

        self.sdrSource.addClient(self)

    def setSecondaryFftSize(self, size):
        self.chain.setSecondaryFftSize(size)
        self.handler.write_secondary_dsp_config({"secondary_fft_size": size})

    def _getDemodulator(self, demod: Union[str, BaseDemodulatorChain]) -> Optional[BaseDemodulatorChain]:
        if isinstance(demod, BaseDemodulatorChain):
            return demod
        # TODO: move this to Modes
        if demod == "nfm":
            from csdr.chain.analog import NFm
            return NFm(self.props["output_rate"])
        elif demod == "wfm":
            from csdr.chain.analog import WFm
            return WFm(self.props["hd_output_rate"], self.props["wfm_deemphasis_tau"])
        elif demod == "am":
            from csdr.chain.analog import Am
            return Am()
        elif demod in ["usb", "lsb", "cw"]:
            from csdr.chain.analog import Ssb
            return Ssb()
        elif demod == "dmr":
            from csdr.chain.digiham import Dmr
            return Dmr(self.props["digital_voice_codecserver"])
        elif demod == "dstar":
            from csdr.chain.digiham import Dstar
            return Dstar(self.props["digital_voice_codecserver"])
        elif demod == "ysf":
            from csdr.chain.digiham import Ysf
            return Ysf(self.props["digital_voice_codecserver"])
        elif demod == "nxdn":
            from csdr.chain.digiham import Nxdn
            return Nxdn(self.props["digital_voice_codecserver"])
        elif demod == "m17":
            from csdr.chain.m17 import M17
            return M17()
        elif demod == "drm":
            from csdr.chain.drm import Drm
            return Drm()
        elif demod == "freedv":
            from csdr.chain.freedv import FreeDV
            return FreeDV()

    def setDemodulator(self, mod):
        self.chain.stopDemodulator()
        try:
            demodulator = self._getDemodulator(mod)
            if demodulator is None:
                raise ValueError("unsupported demodulator: {}".format(mod))
            self.chain.setDemodulator(demodulator)

            output = "hd_audio" if isinstance(demodulator, HdAudio) else "audio"

            if output != self.audioOutput:
                self.audioOutput = output
                # re-wire the audio to the correct client API
                buffer = Buffer(self.chain.getOutputFormat())
                self.chain.setWriter(buffer)
                self.wireOutput(self.audioOutput, buffer)
        except DemodulatorError as de:
            self.handler.write_demodulator_error(str(de))

    def _getSecondaryDemodulator(self, mod) -> Optional[SecondaryDemodulator]:
        if isinstance(mod, SecondaryDemodulator):
            return mod
        if mod in ["ft8", "wspr", "jt65", "jt9", "ft4", "fst4", "fst4w", "q65"]:
            from csdr.chain.digimodes import AudioChopperDemodulator
            from owrx.wsjt import WsjtParser
            return AudioChopperDemodulator(mod, WsjtParser())
        elif mod == "js8":
            from csdr.chain.digimodes import AudioChopperDemodulator
            from owrx.js8 import Js8Parser
            return AudioChopperDemodulator(mod, Js8Parser())
        elif mod == "packet":
            from csdr.chain.digimodes import PacketDemodulator
            return PacketDemodulator()
        elif mod == "pocsag":
            from csdr.chain.digimodes import PocsagDemodulator
            return PocsagDemodulator()
        elif mod == "bpsk31":
            from csdr.chain.digimodes import PskDemodulator
            return PskDemodulator(31.25)
        elif mod == "bpsk63":
            from csdr.chain.digimodes import PskDemodulator
            return PskDemodulator(62.5)

    def setSecondaryDemodulator(self, mod):
        demodulator = self._getSecondaryDemodulator(mod)
        if not demodulator:
            self.chain.setSecondaryDemodulator(None)
        else:
            self.chain.setSecondaryDemodulator(demodulator)

    def setAudioCompression(self, comp):
        try:
            self.chain.setAudioCompression(comp)
        except ValueError:
            # wrong output format... need to re-wire
            buffer = Buffer(self.chain.getOutputFormat())
            self.chain.setWriter(buffer)
            self.wireOutput(self.audioOutput, buffer)

    def start(self):
        if self.sdrSource.isAvailable():
            self.chain.setReader(self.sdrSource.getBuffer().getReader())
        else:
            self.startOnAvailable = True

    def unwireOutput(self, t: str):
        if t in self.readers:
            self.readers[t].stop()
            del self.readers[t]

    def wireOutput(self, t: str, buffer: Buffer):
        logger.debug("wiring new output of type %s", t)
        writers = {
            "audio": self.handler.write_dsp_data,
            "hd_audio": self.handler.write_hd_audio,
            "smeter": self.handler.write_s_meter_level,
            "secondary_fft": self.handler.write_secondary_fft,
            "secondary_demod": self._unpickle(self.handler.write_secondary_demod),
            "meta": self._unpickle(self.handler.write_metadata),
        }

        write = writers[t]

        self.unwireOutput(t)

        reader = buffer.getReader()
        self.readers[t] = reader
        threading.Thread(target=self.chain.pump(reader.read, write), name="dsp_pump_{}".format(t)).start()

    def _unpickle(self, callback):
        def unpickler(data):
            b = data.tobytes()
            io = BytesIO(b)
            try:
                while True:
                    callback(pickle.load(io))
            except EOFError:
                pass
            # TODO: this is not ideal. is there a way to know beforehand if the data will be pickled?
            except pickle.UnpicklingError:
                callback(b.decode("ascii"))

        return unpickler

    def stop(self):
        if self.chain:
            self.chain.stop()
            self.chain = None
        for reader in self.readers.values():
            reader.stop()
        self.readers = {}

        self.startOnAvailable = False
        self.sdrSource.removeClient(self)
        for sub in self.subscriptions:
            sub.cancel()
        self.subscriptions = []

    def setProperties(self, props):
        for k, v in props.items():
            self.setProperty(k, v)

    def setProperty(self, prop, value):
        self.localProps[prop] = value

    def getClientClass(self) -> SdrClientClass:
        return SdrClientClass.USER

    def onStateChange(self, state: SdrSourceState):
        if state is SdrSourceState.RUNNING:
            logger.debug("received STATE_RUNNING, attempting DspSource restart")
            if self.startOnAvailable:
                self.chain.setReader(self.sdrSource.getBuffer().getReader())
                self.startOnAvailable = False
        elif state is SdrSourceState.STOPPING:
            logger.debug("received STATE_STOPPING, shutting down DspSource")
            self.stop()

    def onFail(self):
        logger.debug("received onFail(), shutting down DspSource")
        self.stop()

    def onShutdown(self):
        self.stop()

    def onSecondaryDspBandwidthChange(self, bw):
        self.handler.write_secondary_dsp_config({"secondary_bw": bw})

    def onSecondaryDspRateChange(self, rate):
        self.handler.write_secondary_dsp_config({"if_samp_rate": rate})