first stab at ft8 decoding: chop up audio, call jt9 binary to decode

owrx/wsjt.py

@@ -0,0 +1,79 @@
+import threading
+import wave
+from datetime import datetime, timedelta
+import time
+import sched
+import subprocess
+
+import logging
+logger = logging.getLogger(__name__)
+
+
+class Ft8Chopper(threading.Thread):
+    def __init__(self, source):
+        self.source = source
+        (self.wavefilename, self.wavefile) = self.getWaveFile()
+        self.scheduler = sched.scheduler(time.time, time.sleep)
+        self.queue = []
+        self.doRun = True
+        super().__init__()
+
+    def getWaveFile(self):
+        filename = "/tmp/openwebrx-ft8chopper-{0}.wav".format(datetime.now().strftime("%Y%m%d-%H%M%S"))
+        wavefile = wave.open(filename, "wb")
+        wavefile.setnchannels(1)
+        wavefile.setsampwidth(2)
+        wavefile.setframerate(12000)
+        return (filename, wavefile)
+
+    def getNextDecodingTime(self):
+        t = datetime.now()
+        seconds = (int(t.second / 15) + 1) * 15
+        if seconds >= 60:
+            t = t + timedelta(minutes = 1)
+            seconds = 0
+        t = t.replace(second = seconds, microsecond = 0)
+        logger.debug("scheduling: {0}".format(t))
+        return t.timestamp()
+
+    def startScheduler(self):
+        self._scheduleNextSwitch()
+        threading.Thread(target = self.scheduler.run).start()
+
+    def emptyScheduler(self):
+        for event in self.scheduler.queue:
+            self.scheduler.cancel(event)
+
+    def _scheduleNextSwitch(self):
+        self.scheduler.enterabs(self.getNextDecodingTime(), 1, self.switchFiles)
+
+    def switchFiles(self):
+        file = self.wavefile
+        filename = self.wavefilename
+        (self.wavefilename, self.wavefile) = self.getWaveFile()
+
+        file.close()
+        self.queue.append(filename)
+        self._scheduleNextSwitch()
+
+    def decode(self):
+        if self.queue:
+            file = self.queue.pop()
+            logger.debug("processing file {0}".format(file))
+            #TODO expose decoding quality parameters through config
+            self.decoder = subprocess.Popen(["jt9", "--ft8", "-d", "3", file])
+
+    def run(self) -> None:
+        logger.debug("FT8 chopper starting up")
+        self.startScheduler()
+        while self.doRun:
+            data = self.source.read(256)
+            if data is None or (isinstance(data, bytes) and len(data) == 0):
+                logger.warning("zero read on ft8 chopper")
+                self.doRun = False
+            else:
+                self.wavefile.writeframes(data)
+
+            self.decode()
+        logger.debug("FT8 chopper shutting down")
+        self.emptyScheduler()