if (!(pCtx->pFormatCtx = avformat_alloc_context())) {
		return; //error out of memory
	}
	//create avio context with read_packet function
	unsigned char* ffBuffer = (unsigned char*) av_malloc(
			pBufferCtx->iBufferSize);


	pCtx->pFormatCtx->pb = avio_alloc_context(ffBuffer, pBufferCtx->iBufferSize,
			0, pBufferCtx, &read_packet, NULL, NULL);