sdrplay-fm-radio/radio.py

from threading import Thread
import SoapySDR as soapy
import prefixed
from formats import *
import sys
import subprocess
import struct
from soapyhelpers import *
from samplerates import *
from streamer import Streamer, is_alive


class Radio(Streamer):
    REST_PATH = "radio"
    FORMAT = "CS16"
    SAMPLES = 8192

    def __init__(self, name, device_info):
        super().__init__()

        self.name = name
        self.device_info = device_info
        self.device = soapy.Device(device_info)
        if self.device is None:
            raise RuntimeError("Failed to connect to radio device")

        self.capabilities = self._get_capabilities()

    def configure(self, frequency):
        if self.is_streaming():
            raise RuntimeError("Cannot configure radio while a stream is active")

        frequency = int(prefixed.Float(frequency))
        bandwidth = 200000

        sample_rates = preferred_sample_rates(self.capabilities["rx"]["sample-rates"])
        if len(sample_rates) == 0:
            raise RuntimeError("No suitable sample rates are available")
        self.sample_rate, self.output_rate = sample_rates[0]

        self.device.setFrequency(soapy.SOAPY_SDR_RX, 0, frequency)
        self.device.setSampleRate(soapy.SOAPY_SDR_RX, 0, self.sample_rate)
        self.device.setBandwidth(soapy.SOAPY_SDR_RX, 0, bandwidth)

        # Set automatic gain
        self.device.setGainMode(soapy.SOAPY_SDR_RX, 0, True)

        return {
            "frequency": self.device.getFrequency(soapy.SOAPY_SDR_RX, 0),
            "sample-rate": self.device.getSampleRate(soapy.SOAPY_SDR_RX, 0),
            "bandwidth": self.device.getBandwidth(soapy.SOAPY_SDR_RX, 0),
            "gain-mode": "auto"
            if self.device.getGainMode(soapy.SOAPY_SDR_RX, 0)
            else "manual",
        }

    def get_info(self):
        return {
            "name": self.name,
            "device": self.device_info,
            "capabilities": self.capabilities,
            "stream-path": self._stream_path(),
            "streaming": self.is_streaming(),
        }

    def _get_capabilities(self):
        def get_direction_capabilities(direction):
            return {
                "antennas": self.device.listAntennas(direction, 0),
                "gains": self.device.listGains(direction, 0),
                "frequencies": self.device.listFrequencies(direction, 0),
                "sample-rates": self.device.listSampleRates(direction, 0),
                "bandwidths": self.device.listBandwidths(direction, 0),
                "sensors": self.device.listSensors(direction, 0),
                "formats": self.device.getStreamFormats(direction, 0),
            }

        return {
            "rx": get_direction_capabilities(soapy.SOAPY_SDR_RX),
            "tx": get_direction_capabilities(soapy.SOAPY_SDR_TX),
            "clock-sources": self.device.listClockSources(),
            "time-sources": self.device.listTimeSources(),
            "register-interfaces": self.device.listRegisterInterfaces(),
            "gpios": self.device.listGPIOBanks(),
            "uarts": self.device.listUARTs(),
        }

    def _stream_thread(self):
        self._init_stream()

        while self.run:
            # Check that the child processes are still running
            if (not is_alive(self.demod)) or (not is_alive(self.playback)):
                print("DSP chain failed, aborting stream.", file=sys.stderr)
                break

            result = self.device.readStream(self.stream, [self.buffer], Radio.SAMPLES)

            if result == 0:
                continue
            elif result.ret < 0:
                error = SoapyError(result.ret)
                if error is not SoapyError.Timeout:
                    print(
                        "Stream read failed, aborting stream:", error, file=sys.stderr
                    )
                    break
                continue
            else:
                read_size = int(result.ret * 2)
                self.demod.stdin.write(
                    struct.pack(
                        FORMATS[Radio.FORMAT].packing % read_size,
                        *self.buffer[:read_size],
                    )
                )

        self._cleanup_stream()

    def _init_stream(self):
        self.playback = subprocess.Popen(
            [
                "/usr/bin/ffmpeg",
                "-f",
                "s16le",
                "-ar",
                str(self.output_rate),
                "-ac",
                "2",
                "-i",
                "-",
                "-f",
                "rtsp",
                self.stream_address(),
            ],
            stdin=subprocess.PIPE,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        self.demod = subprocess.Popen(
            [
                "/usr/bin/python3",
                "fm_demod.py",
                "-f",
                "CS16",
                "-s",
                str(self.sample_rate),
                "-d",
                str(self.output_rate),
            ],
            stdin=subprocess.PIPE,
            stdout=self.playback.stdin,
            stderr=subprocess.DEVNULL,
        )

        self.buffer = np.array([0] * Radio.SAMPLES * 2, FORMATS[Radio.FORMAT].numpy)
        self.stream = self.device.setupStream(
            soapy.SOAPY_SDR_RX, FORMATS[Radio.FORMAT].soapy
        )
        result = self.device.activateStream(self.stream)

        if result != 0:
            raise RuntimeError(f"Error activating stream: {result}")

    def _cleanup_stream(self):
        self.run = False

        # Cleanup the streaming objects in the reverse order to the _init method.
        self.device.deactivateStream(self.stream)
        self.device.closeStream(self.stream)
        self.buffer = None

        # .terminate()/.kill() followed by .wait() is required to properly clear
        # killed zombie processes from the process table.
        # https://stackoverflow.com/a/41961462
        self.demod.kill()
        self.demod.wait()
        self.demod = None
        self.playback.kill()
        self.playback.wait()
        self.playback = None


"""
Quick and dirty test of the Radio class.
"""
if __name__ == "__main__":
    import time

    sdr = Radio("demo", {"driver": "sdrplay"})

    print("Configuring...")
    sdr.configure("105.5M")
    print("Configured.")

    print("Starting stream...")
    sdr.start_stream()
    print("Stream started.")

    # Let the stream play for a while
    time.sleep(15)

    print("Ending stream...")
    sdr.end_stream()
    print("Stream ended.")