Ttyrec

A ttyrec is a recording of a terminal. For example, you can play a game of NetHack in a text-mode terminal, and record everything that NetHack shows. nethack.alt.org records all games.

ttyrec files can be played back with several programs:

• IPBT
• playttyrec.c (also see https://www.stack.nl/~jilles/games/)
• ttyplay and ttyrec
• Termplay
• Jettyplay

ttyrec format

A ttyrec consists of many frames. Each frame is made up of a twelve-byte header and an arbitrarily long data block. The twelve-byte header contains two pieces of information: how much data is in this frame and a timestamp. The timestamp is very precise; it has microsecond precision. The header bytes are aligned like so:

1 2 3 4 5 6 7 8 9 A B C
\-----/ \-----/ \-----/
  sec     usec    len

The bytes are in little-endian order (meaning least significant bytes first). You can portably read and process frames like this, in C:

while (fread(header, 1, 12, stdin) == 12)
{
  sec  = (((((header[ 3] << 8) | header[ 2]) << 8) | header[1]) << 8) | header[0];
  usec = (((((header[ 7] << 8) | header[ 6]) << 8) | header[5]) << 8) | header[4];
  len  = (((((header[11] << 8) | header[10]) << 8) | header[9]) << 8) | header[8];

  received = fread(data, 1, len, stdin)
  if (len != received)
    break;

  /* process data */
}

/* either the ttyrec is done or we had an error */

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