return AVERROR_INVALIDDATA;
url_fseek(pb, seq->current_frame_offs + data_offs, SEEK_SET);
if (get_buffer(pb, seq_buffer->data + seq_buffer->fill_size, data_size) != data_size)
return AVERROR_INVALIDDATA;
url_fseek(pb, seq->current_frame_offs + data_offs, SEEK_SET);
if (get_buffer(pb, seq_buffer->data + seq_buffer->fill_size, data_size) != data_size)