first steps adding RDS decoding with redsea

csdr/chain/analog.py

@@ -1,6 +1,10 @@
-from csdr.chain.demodulator import BaseDemodulatorChain, FixedIfSampleRateChain, HdAudio, DeemphasisTauChain
-from pycsdr.modules import AmDemod, DcBlock, FmDemod, Limit, NfmDeemphasis, Agc, WfmDeemphasis, FractionalDecimator, RealPart
+from csdr.chain.demodulator import BaseDemodulatorChain, FixedIfSampleRateChain, HdAudio, DeemphasisTauChain, MetaProvider
+from pycsdr.modules import AmDemod, DcBlock, FmDemod, Limit, NfmDeemphasis, Agc, WfmDeemphasis, FractionalDecimator, \
+    RealPart, Writer, Buffer
 from pycsdr.types import Format, AgcProfile
+from csdr.chain.redsea import Redsea
+from typing import Optional
+from owrx.feature import FeatureDetector
 
 
 class Am(BaseDemodulatorChain):
@@ -38,18 +42,27 @@ class NFm(BaseDemodulatorChain):
         self.replace(2, NfmDeemphasis(sampleRate))
 
 
-class WFm(BaseDemodulatorChain, FixedIfSampleRateChain, DeemphasisTauChain, HdAudio):
+class WFm(BaseDemodulatorChain, FixedIfSampleRateChain, DeemphasisTauChain, HdAudio, MetaProvider):
     def __init__(self, sampleRate: int, tau: float):
         self.sampleRate = sampleRate
         self.tau = tau
+        self.limit = Limit()
+        # this buffer is used to tap into the raw audio stream for redsea RDS decoding
+        self.metaTapBuffer = Buffer(Format.FLOAT)
         workers = [
             FmDemod(),
-            Limit(),
+            self.limit,
             FractionalDecimator(Format.FLOAT, 200000.0 / self.sampleRate, prefilter=True),
             WfmDeemphasis(self.sampleRate, self.tau),
         ]
+        self.metaChain = None
         super().__init__(workers)
 
+    def _connect(self, w1, w2, buffer: Optional[Buffer] = None) -> None:
+        if w1 is self.limit:
+            buffer = self.metaTapBuffer
+        super()._connect(w1, w2, buffer)
+
     def getFixedIfSampleRate(self):
         return 200000
 
@@ -66,6 +79,14 @@ class WFm(BaseDemodulatorChain, FixedIfSampleRateChain, DeemphasisTauChain, HdAu
         self.replace(2, FractionalDecimator(Format.FLOAT, 200000.0 / self.sampleRate, prefilter=True))
         self.replace(3, WfmDeemphasis(self.sampleRate, self.tau))
 
+    def setMetaWriter(self, writer: Writer) -> None:
+        if not FeatureDetector().is_available("redsea"):
+            return
+        if self.metaChain is None:
+            self.metaChain = Redsea(self.getFixedIfSampleRate())
+            self.metaChain.setReader(self.metaTapBuffer.getReader())
+        self.metaChain.setWriter(writer)
+
 
 class Ssb(BaseDemodulatorChain):
     def __init__(self):

csdr/chain/redsea.py

@@ -0,0 +1,14 @@
+from csdr.chain import Chain
+from pycsdr.modules import Convert
+from pycsdr.types import Format
+from owrx.rds.redsea import RedseaModule
+from csdr.module import JsonParser
+
+
+class Redsea(Chain):
+    def __init__(self, sampleRate: int):
+        super().__init__([
+            Convert(Format.FLOAT, Format.SHORT),
+            RedseaModule(sampleRate),
+            JsonParser("RDS"),
+        ])

owrx/feature.py

@@ -89,6 +89,7 @@ class FeatureDetector(object):
         "ism": ["rtl_433"],
         "dumphfdl": ["dumphfdl"],
         "dumpvdl2": ["dumpvdl2"],
+        "redsea": ["redsea"],
     }
 
     def feature_availability(self):
@@ -636,3 +637,14 @@ class FeatureDetector(object):
         `dumpvdl2`.
         """
         return self.command_is_runnable("dumpvdl2 --version")
+
+    def has_redsea(self):
+        """
+        OpenWebRX can decode RDS data on WFM broadcast station if the `redsea` decoder is available.
+
+        You can find more information [here](https://github.com/windytan/redsea)
+
+        If you are using the OpenWebRX Debian or Ubuntu repository, you should be able to install the package
+        `redsea`.
+        """
+        return self.command_is_runnable("redsea --version")

owrx/rds/redsea.py

@@ -0,0 +1,11 @@
+from pycsdr.modules import ExecModule
+from pycsdr.types import Format
+
+
+class RedseaModule(ExecModule):
+    def __init__(self, sampleRate: int):
+        super().__init__(
+            Format.SHORT,
+            Format.CHAR,
+            ["redsea", "--input", "mpx", "--samplerate", str(sampleRate)]
+        )