PA: Adjust Input Fragsize / Latency;

M17: Misc Notes About UDP Audio;

src/dsd_audio.c

@@ -23,6 +23,9 @@ pa_sample_spec zz;
 pa_sample_spec cc;
 pa_sample_spec ff; //float
 
+//pulse audio buffer attributes (input latency)
+pa_buffer_attr lt;
+
 void closePulseOutput (dsd_opts * opts)
 {
   pa_simple_free (opts->pulse_digi_dev_out);
@@ -72,7 +75,34 @@ void openPulseInput(dsd_opts * opts)
   cc.channels = opts->pulse_digi_in_channels;
   cc.rate = opts->pulse_digi_rate_in; //48000
 
-  opts->pulse_digi_dev_in  = pa_simple_new(NULL, "DSD-FME", PA_STREAM_RECORD, NULL, opts->output_name, &cc, NULL, NULL, NULL);
+  //adjust input latency settings (defaults are all -1 to let server set these automatically, but without pavucontrol open, this is approx 2s)
+  //setting fragsize to 960 for 48000 input seems to do the trick to allow a much faster latency without underrun, may need adjusting if
+  //modifying the input rate (will only apply IF using pulse audio input, and not any other input method)
+
+  //TODO: set fragsize vs expected input rate if required in the future
+  //NOTE: If users report any underrun conditions, then either change 960 back to -1, or pass NULL instead of &lt
+
+  //https://freedesktop.org/software/pulseaudio/doxygen/structpa__buffer__attr.html
+
+  //for now, only going to modify the fragsize if using the encoder, else, let the pa server set it automatically
+  // if (opts->m17encoder == 1)
+  //   lt.fragsize = 960*5;
+  // else lt.fragsize = -1;
+
+  //test doing it universally, fall back to above if needed
+  lt.fragsize = 960*5;
+  lt.maxlength = -1;
+  lt.prebuf = -1;
+  lt.tlength = -1;
+
+  opts->pulse_digi_dev_in  = pa_simple_new(NULL, "DSD-FME", PA_STREAM_RECORD, NULL, opts->output_name, &cc, NULL, &lt, NULL);
+
+  //debug
+  // if (opts->m17encoder == 1)
+  // {
+  //   unsigned long long int latency = pa_simple_get_latency (opts->pulse_digi_dev_in, NULL);
+  //   fprintf (stderr, "Pulse Audio Input Latency: %05lld;", latency);
+  // }
 
 }
 

src/dsd_rigctl.c

@@ -307,16 +307,16 @@ int udp_socket_blaster(dsd_opts * opts, dsd_state * state, size_t nsam, void * d
     //listen with:
 
     //short 8k/2
-    //socat stdio udp-listen:23456 | play --buffer 320*2 -q -b 16 -r 8000 -c2 -t s16 -
+    //socat stdio udp-listen:23456 | play --buffer 640 -q -b 16 -r 8000 -c2 -t s16 -
 
     //short 8k/1
-    //socat stdio udp-listen:23456 | play --buffer 160*2 -q -b 16 -r 48000 -c2 -t s16 -
+    //socat stdio udp-listen:23456 | play --buffer 320 -q -b 16 -r 8000 -c1 -t s16 -
 
     //float 8k/2
-    //socat stdio udp-listen:23456 | play --buffer 320*4 -q -e float -b 32 -r 8000 -c2 -t f32 -
+    //socat stdio udp-listen:23456 | play --buffer 1280 -q -e float -b 32 -r 8000 -c2 -t f32 -
 
     //float 8k/1
-    //socat stdio udp-listen:23456 | play --buffer 160*4 -q -e float -b 32 -r 8000 -c1 -t f32 -
+    //socat stdio udp-listen:23456 | play --buffer 640 -q -e float -b 32 -r 8000 -c1 -t f32 -
 
     //send audio or data to socket
     err = sendto(opts->udp_sockfd, data, nsam, 0, (const struct sockaddr * ) & address, sizeof(struct sockaddr_in));
@@ -345,7 +345,7 @@ int udp_socket_blasterA(dsd_opts * opts, dsd_state * state, size_t nsam, void *
     //listen with:
 
     //short 48k/1
-    //socat stdio udp-listen:23456 | play --buffer 960*2 -q -b 16 -r 48000 -c1 -t s16 -
+    //socat stdio udp-listen:23456 | play --buffer 1920 -q -b 16 -r 48000 -c1 -t s16 -
 
     //send audio or data to socket
     err = sendto(opts->udp_sockfdA, data, nsam, 0, (const struct sockaddr * ) & addressA, sizeof(struct sockaddr_in));
@@ -358,10 +358,7 @@ int m17_socket_blaster(dsd_opts * opts, dsd_state * state, size_t nsam, void * d
     UNUSED(state);
     unsigned long long int err = 0;
 
-    //listen with:
+    //See notes in m17.c on line ~3395 regarding usage
-
-    //XX packed bytes
-    //socat stdio udp-listen:17000 | (decoder)
 
     //send audio or data to socket
     err = sendto(opts->m17_udp_sock, data, nsam, 0, (const struct sockaddr * ) & addressM17, sizeof(struct sockaddr_in));

src/m17.c

@@ -2156,6 +2156,13 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
         fprintf (stderr, " SQL HIT: %d;", sql_hit);
       }
 
+      //debug show pulse input latency
+      // if (opts->audio_in_type == 0)
+      // {
+      //   unsigned long long int latency = pa_simple_get_latency (opts->pulse_digi_dev_in, NULL);
+      //   fprintf (stderr, " Latency: %05lld;", latency);
+      // }
+
       //convert bit array into symbols and RF/Audio
       encodeM17RF (opts, state, m17_t4s, 2);
       
@@ -3398,6 +3405,9 @@ void processM17IPF(dsd_opts * opts, dsd_state * state)
   //encode with: dsd-fme -fZ -M M17:1:N0CALL:ALL:48000:1 -o m17:127.0.0.1:17000 -N 2> m17out.ans
   //decode with: dsd-fme -fU -i m17:127.0.0.1:17000 -N 2> m17ip.ans
 
+  //NOTE: Currently, IP Frame decoding cannot be used with -o udp audio output
+  //its a rare use case, but should be noted, I think udpbind does something to block that functionality
+
   //Bind UDP Socket
   int err = 1; //NOTE: err will tell us how many bytes were received, if successful
   opts->udp_sockfd = UDPBind(opts->m17_hostname, opts->m17_portno);