avio_skip(pb,4); /* skip FORM tag */
back_size = avio_rl32(pb); /**< get size of the background frame */
signature = avio_rb32(pb);
avio_skip(pb,4); /* skip FORM tag */
back_size = avio_rl32(pb); /**< get size of the background frame */
signature = avio_rb32(pb);
frame_count = avio_rl32(pb);
/* disallow back_sizes and frame_counts that may lead to overflows later */
if(back_size > INT_MAX/2 || frame_count > INT_MAX / sizeof(uint32_t))
return AVERROR_INVALIDDATA;
frame_count = avio_rl32(pb);
/* disallow back_sizes and frame_counts that may lead to overflows later */
if(back_size > INT_MAX/2 || frame_count > INT_MAX / sizeof(uint32_t))
return AVERROR_INVALIDDATA;