Swapped audio channels

[romekb]

I found bug in Audio::Gain function causing audio channel swapping and wrong balance operation.
The correct function should look like this:

int32_t Audio::Gain(int16_t s[2]) {
   int32_t v[2];
   float step = (float)m_vol /254;
   uint8_t l = 0, r = 0;

   if(m_balance < 0){
       step = step * (float)(abs(m_balance) * 16);
       r = (uint8_t)(step);            // bugfix
   }
   if(m_balance > 0){
       step = step * m_balance * 16;
       l = (uint8_t)(step);            // bugfix
   }

   v[LEFTCHANNEL] = (s[LEFTCHANNEL]  * (m_vol - l)) >> 8;
   v[RIGHTCHANNEL]= (s[RIGHTCHANNEL] * (m_vol - r)) >> 8;

   return (v[RIGHTCHANNEL] << 16) | (v[LEFTCHANNEL] & 0xffff);   // bugfix
} 

[enjoyneering]

please open here - https://github.com/schreibfaul1/ESP32-audioI2S

[romekb]

This library use different way to control volume and balance.
This bug only occurs in the yoRadio code.