trx-bridge: timestamp improvements

trx-bridge/bridge.c

@@ -2,6 +2,7 @@
 
 // Size of TRX buffer in IQ samples (complex)
 #define TRX_BUFFER_SIZE 4096
+#define SAMPLE_RATE_KHZ 30720
 
 char *bridge_trx_input_get_param_string(void *app_opaque, const char *prop_name) {
 	return potoml_toml_get_string((struct PotomlTomlSubset *) app_opaque, prop_name);
@@ -300,7 +301,6 @@ int main(int argc, char *argv[]) {
 
 	while(1) {
 		// Read from output first to know how many samples should be read
-		output_rx_ts = 0;
 		output_read_count = output_trx_state.trx_read_func2(&output_trx_state, &output_rx_ts, (void **) output_channels, TRX_BUFFER_SIZE, 0, &read_md);
 
 		// As much samples should be read from input than from output.
@@ -314,7 +314,7 @@ int main(int argc, char *argv[]) {
 
 			input_read_count_extra = input_trx_state.trx_read_func2(&input_trx_state, &input_rx_ts, (void **) input_channels, output_read_count - input_read_count, 0, &read_md);
 			// If no samples can be read, escape from infinite loop
-			// This return to operations, but will discard some frames
+			// This return to operations, but might discard some frames
 			if(input_read_count_extra == 0) break;
 			input_read_count += input_read_count_extra;
 		}
@@ -323,25 +323,26 @@ int main(int argc, char *argv[]) {
 		// timestamp and incremented after every write.
 		// The buffer size in TRX SDR is four times the samples rate, so this
 		// value is used here as tn offset between the two timestamps.
-		if(output_tx_ts == 0) output_tx_ts = output_rx_ts + 4 * 23040;
-		if(input_tx_ts == 0) input_tx_ts = input_rx_ts + 4 * 23040;
+		if(output_tx_ts == 0) output_tx_ts = output_rx_ts + 4 * SAMPLE_RATE_KHZ;
+		if(input_tx_ts == 0) input_tx_ts = input_rx_ts + 4 * SAMPLE_RATE_KHZ;
+
+		output_tx_ts += output_read_count;
+		input_tx_ts += input_read_count;
+
+		// Write back samples read from input and output
+		if(input_read_count > 0) output_trx_state.trx_write_func2(&output_trx_state, output_tx_ts, (const void **) input_channels, input_read_count, 0, &write_md);
+		if(output_read_count > 0) input_trx_state.trx_write_func2(&input_trx_state, input_tx_ts, (const void **) output_channels, output_read_count, 0, &write_md);
 
 		// Real behavior: sometimes, the TX timestamp deviates, so it should be matched again.
-		if(output_tx_ts != output_rx_ts + 4 * 23040) {
-			printf("Output timestamp don't match %lu != %lu\n", output_tx_ts, output_rx_ts + 4 * 23040);
-			output_tx_ts = output_rx_ts + 4 * 23040;
+		if(output_tx_ts != output_rx_ts + 4 * SAMPLE_RATE_KHZ) {
+			printf("trx-bridge: output timestamp deviated %lu != %lu\n", output_tx_ts, output_rx_ts + 4 * SAMPLE_RATE_KHZ);
+			output_tx_ts = output_rx_ts + 4 * SAMPLE_RATE_KHZ;
 		}
 
-		if(input_tx_ts != input_rx_ts + 4 * 23040) {
-			printf("Input timestamp don't match %lu != %lu\n", input_tx_ts, input_rx_ts + 4 * 23040);
-			input_tx_ts = input_rx_ts + 4 * 23040;
+		if(input_tx_ts != input_rx_ts + 4 * SAMPLE_RATE_KHZ) {
+			printf("trx-bridge: input timestamp deviated %lu != %lu\n", input_tx_ts, input_rx_ts + 4 * SAMPLE_RATE_KHZ);
+			input_tx_ts = input_rx_ts + 4 * SAMPLE_RATE_KHZ;
 		}
-
-		output_trx_state.trx_write_func2(&output_trx_state, output_tx_ts, (const void **) input_channels_base, input_read_count, 0, &write_md);
-		output_tx_ts += input_read_count;
-
-		input_trx_state.trx_write_func2(&input_trx_state, input_tx_ts, (const void **) output_channels, output_read_count, 0, &write_md);
-		input_tx_ts += output_read_count;
 	}
 
 	dlclose(input_lib_handle);