RVA2ChannelTypeLookup example

$frame_idstring = substr($parsedFrame['data'], 0, $frame_terminatorpos);
            if (ord($frame_idstring) === 0) {
                $frame_idstring = '';
            }
            $frame_remainingdata = substr($parsedFrame['data'], $frame_terminatorpos + strlen("\x00"));
            $parsedFrame['description'] = $frame_idstring;
            $RVA2channelcounter = 0;
            while (strlen($frame_remainingdata) >= 5) {
                $frame_offset = 0;
                $frame_channeltypeid = ord(substr($frame_remainingdata, $frame_offset++, 1));
                $parsedFrame[$RVA2channelcounter]['channeltypeid']  = $frame_channeltypeid;
                $parsedFrame[$RVA2channelcounter]['channeltype']    = $this->RVA2ChannelTypeLookup($frame_channeltypeid);
                $parsedFrame[$RVA2channelcounter]['volumeadjust']   = getid3_lib::BigEndian2Int(substr($frame_remainingdata, $frame_offset, 2), false, true); // 16-bit signed                 $frame_offset += 2;
                $parsedFrame[$RVA2channelcounter]['bitspeakvolume'] = ord(substr($frame_remainingdata, $frame_offset++, 1));
                if (($parsedFrame[$RVA2channelcounter]['bitspeakvolume'] < 1) || ($parsedFrame[$RVA2channelcounter]['bitspeakvolume'] > 4)) {
                    $this->warning('ID3v2::RVA2 frame['.$RVA2channelcounter.'] contains invalid '.$parsedFrame[$RVA2channelcounter]['bitspeakvolume'].'-byte bits-representing-peak value');
                    break;
                }
                $frame_bytespeakvolume = ceil($parsedFrame[$RVA2channelcounter]['bitspeakvolume'] / 8);
                $parsedFrame[$RVA2channelcounter]['peakvolume']     = getid3_lib::BigEndian2Int(substr($frame_remainingdata, $frame_offset, $frame_bytespeakvolume));
                $frame_remainingdata = substr($frame_remainingdata, $frame_offset + $frame_bytespeakvolume);
                $RVA2channelcounter++;
            }