docs: private int getPacketSize(Format codecFormat, int milliseconds) throws IllegalArgumentException {
          String encoding = codecFormat.getEncoding();
          if (encoding.equalsIgnoreCase(AudioFormat.GSM) ||
                  encoding.equalsIgnoreCase(AudioFormat.GSM_RTP)) {
              return milliseconds * 4; // 1 byte per millisec
          }
          else if (encoding.equalsIgnoreCase(AudioFormat.ULAW) ||
                  encoding.equalsIgnoreCase(AudioFormat.ULAW_RTP)) {
              return milliseconds * 8;
          }
          else {
              throw new IllegalArgumentException("Unknown codec type");
          }
      }