[SSTV] Moved correction factor to its own method

examples/SSTV/SSTV_Transmit/SSTV_Transmit.ino

@@ -107,7 +107,16 @@ void setup() {
   Serial.print(F("[SSTV] Initializing ... "));
   // 0 Hz tone frequency:         434.0 MHz
   // SSTV mode:                   Wrasse (SC2-180)
-  // correction factor:           0.95
+  state = sstv.begin(434.0, Wrasse);
+  if(state == RADIOLIB_ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while(true);
+  }
+
+  // set correction factor
   // NOTE: Due to different speeds of various platforms
   //       supported by RadioLib (Arduino Uno, ESP32 etc),
   //       and because SSTV is analog protocol, incorrect
@@ -116,7 +125,8 @@ void setup() {
   //       to adjust the length of timing pulses
   //       (lower number = shorter pulses).
   //       The value is usually around 0.95 (95%).
-  state = sstv.begin(434.0, Wrasse, 0.95);
+  Serial.print(F("[SSTV] Setting correction ... "));
+  state = sstv.setCorrection(0.95);
   if(state == RADIOLIB_ERR_NONE) {
     Serial.println(F("success!"));
   } else {

examples/SSTV/SSTV_Transmit_AFSK/SSTV_Transmit_AFSK.ino

@@ -105,7 +105,16 @@ void setup() {
   // initialize SSTV client
   Serial.print(F("[SSTV] Initializing ... "));
   // SSTV mode:                   Wrasse (SC2-180)
-  // correction factor:           0.95
+  state = sstv.begin(Wrasse);
+  if(state == RADIOLIB_ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while(true);
+  }
+
+  // set correction factor
   // NOTE: Due to different speeds of various platforms
   //       supported by RadioLib (Arduino Uno, ESP32 etc),
   //       and because SSTV is analog protocol, incorrect
@@ -114,7 +123,8 @@ void setup() {
   //       to adjust the length of timing pulses
   //       (lower number = shorter pulses).
   //       The value is usually around 0.95 (95%).
-  state = sstv.begin(Wrasse, 0.95);
+  Serial.print(F("[SSTV] Setting correction ... "));
+  state = sstv.setCorrection(0.95);
   if(state == RADIOLIB_ERR_NONE) {
     Serial.println(F("success!"));
   } else {

src/protocols/SSTV/SSTV.cpp

@@ -169,26 +169,20 @@ SSTVClient::SSTVClient(AFSKClient* audio) {
 #endif
 
 #if !defined(RADIOLIB_EXCLUDE_AFSK)
-int16_t SSTVClient::begin(const SSTVMode_t& mode, float correction) {
+int16_t SSTVClient::begin(const SSTVMode_t& mode) {
   if(_audio == nullptr) {
     // this initialization method can only be used in AFSK mode
     return(RADIOLIB_ERR_WRONG_MODEM);
   }
 
-  return(begin(0, mode, correction));
+  return(begin(0, mode));
 }
 #endif
 
-int16_t SSTVClient::begin(float base, const SSTVMode_t& mode, float correction) {
+int16_t SSTVClient::begin(float base, const SSTVMode_t& mode) {
   // save mode
   _mode = mode;
 
-  // apply correction factor to all timings
-  _mode.scanPixelLen *= correction;
-  for(uint8_t i = 0; i < _mode.numTones; i++) {
-    _mode.tones[i].len *= correction;
-  }
-
   // calculate 24-bit frequency
   _base = (base * 1000000.0) / _phy->getFreqStep();
 
@@ -196,6 +190,20 @@ int16_t SSTVClient::begin(float base, const SSTVMode_t& mode, float correction)
   return(_phy->startDirect());
 }
 
+int16_t SSTVClient::setCorrection(float correction) {
+  // check if mode is initialized
+  if(_mode.visCode == 0) {
+    return(RADIOLIB_ERR_WRONG_MODEM);
+  }
+
+  // apply correction factor to all timings
+  _mode.scanPixelLen *= correction;
+  for(uint8_t i = 0; i < _mode.numTones; i++) {
+    _mode.tones[i].len *= correction;
+  }
+  return(RADIOLIB_ERR_NONE);
+}
+
 void SSTVClient::idle() {
   _phy->transmitDirect();
   this->tone(RADIOLIB_SSTV_TONE_LEADER);

src/protocols/SSTV/SSTV.h

@@ -144,11 +144,9 @@ class SSTVClient {
 
       \param mode SSTV mode to be used. Currently supported modes are Scottie1, Scottie2, ScottieDX, Martin1, Martin2, Wrasse, PasokonP3, PasokonP5 and PasokonP7.
 
-      \param correction Timing correction factor, used to adjust the length of timing pulses. Less than 1.0 leads to shorter timing pulses, defaults to 1.0 (no correction).
-
       \returns \ref status_codes
     */
-    int16_t begin(float base, const SSTVMode_t& mode, float correction = 1.0);
+    int16_t begin(float base, const SSTVMode_t& mode);
 
     #if !defined(RADIOLIB_EXCLUDE_AFSK)
     /*!
@@ -156,12 +154,19 @@ class SSTVClient {
 
       \param mode SSTV mode to be used. Currently supported modes are Scottie1, Scottie2, ScottieDX, Martin1, Martin2, Wrasse, PasokonP3, PasokonP5 and PasokonP7.
 
+      \returns \ref status_codes
+    */
+    int16_t begin(const SSTVMode_t& mode);
+    #endif
+
+    /*!
+      \brief Set correction coefficient for tone length.
+
       \param correction Timing correction factor, used to adjust the length of timing pulses. Less than 1.0 leads to shorter timing pulses, defaults to 1.0 (no correction).
 
       \returns \ref status_codes
     */
-    int16_t begin(const SSTVMode_t& mode, float correction = 1.0);
-    #endif
+    int16_t setCorrection(float correction);
 
     /*!
       \brief Sends out tone at 1900 Hz.