Formula for counting frame length in Bytes:
FrameLen = int((144 * BitRate / SampleRate ) + Padding);
Eg. for Bitrate = 192kbps, SampleRate = 44.1kHz a Padding = Yes
FrameLen = int((144 * 192000 / 44100) + 1) = 627 Bytes
int() means round to bottom. FrameLen includes frame header.