fread, fwrite for big size video file (about 180MB)

Question

I want to read a video file and save as binary and write as a video file again. I tested with 180MB video. I used fread function and It occur segmentation fault because array size is small for video.

those are my questions:

1. I use 160*1024 bytes char array. What is the maximum size of char array? How I can solve this problem?

2. this program need to work as:

   • read 128 bytes of video -> Encrypt -> write 128 byte
   • read next 128 bytes -> Encrypt -> write to the next.

I can't upload my code because of security rule of company. Any tip would be appreciated.

Answer 1

first use fseek() with SEEK_END, then use ftell() to determine the file size, after that allocate the needed memory with malloc() and write the data to that memory.

If I understand you correctly you don't need to allocate so much memory, but only 128 Bytes.

char buf[128];
while(/* condition */)
{
  ret = fread(buf, sizeof buf, 1, fp_in);
  encrypt(buf);
  ret = fwrite(buf, sizeof buf, 1, fp_out);
}