// from http://www.xingtech.com/developer/mp3/
const size_t VBR_HEADER_MIN_SIZE = 8; // "xing" + flags are fixed
const size_t VBR_HEADER_MAX_SIZE = 116; // frames, bytes, toc and scale are optional
const size_t VBR_HEADER_MAX_SIZE = 120; // frames, bytes, toc and scale are optional
if (mp3size >= vbr_header_offest + VBR_HEADER_MIN_SIZE)
{