[feat](trx-rds,trx-frontend-http): reset rds on tune changes

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs

@@ -149,6 +149,10 @@ impl WfmStereoDecoder {
     pub fn rds_data(&self) -> Option<RdsData> {
         self.rds_decoder.snapshot()
     }
+
+    pub fn reset_rds(&mut self) {
+        self.rds_decoder.reset();
+    }
 }
 
 /// Selects the demodulation algorithm for a channel.

src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs

@@ -502,6 +502,12 @@ impl ChannelDsp {
         self.wfm_decoder.as_ref().and_then(WfmStereoDecoder::rds_data)
     }
 
+    pub fn reset_rds(&mut self) {
+        if let Some(decoder) = &mut self.wfm_decoder {
+            decoder.reset_rds();
+        }
+    }
+
     /// Process a block of raw IQ samples through the full DSP chain.
     ///
     /// 1. **Batch mixer**: compute the full LO signal for the block at once,

src/trx-server/trx-backend/trx-backend-soapysdr/src/lib.rs

@@ -252,6 +252,7 @@ impl RigCat for SoapySdrRig {
     ) -> Pin<Box<dyn std::future::Future<Output = DynResult<()>> + Send + 'a>> {
         Box::pin(async move {
             tracing::debug!("SoapySdrRig: set_freq -> {} Hz", freq.hz);
+            let freq_changed = self.freq.hz != freq.hz;
             self.freq = freq;
             let half_span_hz = i128::from(self.pipeline.sdr_sample_rate) / 2;
             let current_center_hz = i128::from(self.center_hz);
@@ -271,7 +272,11 @@ impl RigCat for SoapySdrRig {
 
             if let Some(dsp_arc) = self.pipeline.channel_dsps.get(self.primary_channel_idx) {
                 let channel_if_hz = (self.freq.hz as i64 - self.center_hz) as f64;
-                dsp_arc.lock().unwrap().set_channel_if_hz(channel_if_hz);
+                let mut dsp = dsp_arc.lock().unwrap();
+                dsp.set_channel_if_hz(channel_if_hz);
+                if freq_changed {
+                    dsp.reset_rds();
+                }
             }
             Ok(())
         })