Provided by: its-playback-time_0.2017-08-30.3c40fd3-1_amd64 
NAME
ipbt - play back tty recording files with random access
SYNOPSIS
ipbt [ options ] file [ file ... ]
DESCRIPTION
ipbt is a curses-based playback utility for recordings of terminal sessions in either ttyrec or nh-
recorder format.
ttyrec and nh-recorder are both programs which record the output of a terminal session, interspersed with
timestamps. This allows the session to be replayed on another terminal at the original speed, so that the
replaying terminal screen looks identical to the original, provided the recording and replaying terminals
are sufficiently compatible. ttyrec and nh-recorder produce differently formatted files, but the
principle is very similar.
To replay a tty recording in a forward direction, a program such as ttyplay will simply write the
contents of the file to the output terminal, stopping to wait for the appropriate period every time it
encounters a timestamp. Speeding up, slowing down and pausing the replay are easy. Rewinding, however, is
almost impossible with this replay architecture.
ipbt solves this by running the entire tty recording through an internal terminal emulator and storing
the resulting screen contents in a manner that permits random access. Once this loading process is
complete, ipbt can play forwards and backwards, or jump to an arbitrary point in the recording, with
equal ease.
This flexibility comes with two disadvantages:
• ipbt takes noticeable time to load a tty recording in the first place. At the time of writing
this, it typically takes a few seconds per megabyte of input. Simpler programs such as ttyplay can
begin playing instantly.
• Since ipbt does its terminal emulation internally, it can support only one type of terminal,
namely that provided by PuTTY (of which ipbt is a derived work). Any tty recording which is not
compatible with that terminal type will not come out looking right. Simpler programs such as
ttyplay rely on the terminal they are running in to interpret the terminal control sequences, so
they can be made to support any terminal type simply by running them in that type of terminal.
If either of these is a serious problem, you probably don't want to be using ipbt.
OPTIONS
By default, ipbt interprets tty recordings as if they were intended to be replayed on an 80×24 screen.
You can alter this using the following options:
-w width
Set the width of the emulated terminal to width columns.
-h height
Set the height of the emulated terminal to height rows.
-u Set the width and height of the emulated terminal to be the same as that of the real terminal in
which you are running ipbt.
By default, ipbt will attempt to analyse the input files and automatically guess whether they are in
ttyrec or nh-recorder format. On rare occasions this automatic guessing may fail: for example, a ttyrec
made on a system whose clock occasionally jumps backwards may contain timestamps in non-increasing order,
in which case ipbt may consider the file not to be a valid ttyrec and either try to interpret it as nh-
recorder format or (more likely) refuse to load it at all. If this happens, you will need to explicitly
tell ipbt what type of file it is dealing with using the following options:
-T Specify that all files appearing on the command line after this point (until a subsequent format-
specifying option) should be assumed to be in ttyrec format.
-N Specify that all files appearing on the command line after this point (until a subsequent format-
specifying option) should be assumed to be in nh-recorder format.
ipbt also provides the following miscellaneous options:
-f frame
After loading the tty recordings, jump to the specified frame number. Frame numbers are allocated
starting from zero, as if all the input files were concatenated; so if you provided two input
files, one with 100 frames and one with 50, then frame numbers 0-99 would indicate positions in
the first file and frame numbers 100-149 would indicate positions in the second.
-P After loading the tty recordings, terminate immediately. This option is unlikely to be very useful
at present, although it might have specialist uses for people wanting to measure ipbt's loading
speed or test its automatic format detection.
-U Treat the input terminal data as being encoded in UTF-8.
If ipbt has been compiled against the ncursesw library and is running in a UTF-8 terminal, it will
reproduce the Unicode characters in the input file as faithfully as it can. If not, it will at
least try to reproduce as many of the characters as it can on whatever terminal it does have.
PLAYING
Once ipbt has loaded a set of tty recordings, it enters a full-screen playing mode. This section
describes the keypresses which control the player.
To terminate the player, press `q', or Control-C.
Press `p' or `s' to toggle between pause and play mode. The player starts up in pause mode, so you may
well want to press this immediately to begin playing.
To go back by one frame, press `b' or `<'. To go back by many frames, type a number followed by `b' or
`<'.
To go forward by one frame, press the space bar or `>'. To go back by many frames, type a number followed
by the space bar or `>'.
To jump to a particular frame number, type the number followed by `g'. Pressing `g' on its own will jump
to the start of the recording.
Pressing capital `G' will jump to the end of the recording. If you type a number followed by `G', it will
jump to that many frames before the end.
To play back the recording at higher speed, type a number followed by `x'. For example, typing `3x' will
set the player to three times normal speed. (This will not automatically bring you out of pause mode; you
still need to press `p' or `s' for that.)
To play back at a lower speed, type a number followed by capital `X'; for example, `3X' will set the
player to one-third normal speed.
To return to normal speed, you can type `1x' or `1X', or just `x' or `X'.
If you press `l', the player will toggle logarithmic time compression. This is a mode in which the delay
between frames is scaled in a non-linear fashion: small delays are changed very little, but extremely
large delays are made significantly less large, so that an hour between frames in the original recording
becomes only about eight seconds, a day becomes eleven, and even a year between frames would become
around seventeen seconds. This is helpful if the person who made the recording left the terminal for a
long time in the middle of their session. Logarithmic mode can be used in conjunction with the `x'/`X'
scaling feature.
If you press `o', the player will show an on-screen display near the top left of the screen, showing the
current frame number and playback settings. Press `o' again to make the display go away.
You can also search the recording for a frame in which a particular piece of text appears on the screen.
Press `/' to search forwards from the current position, or `\' or `?' to search backwards. Each of these
commands will cause ipbt to prompt for a piece of text to find, and will then search for a frame that
contains that text. Press `n' to search for the same piece of text again in the same direction.
BUGS
ipbt's internal terminal emulation is that of PuTTY, but its display of the resulting data is rather more
simplistic. Some output features supported by PuTTY are therefore not supported by ipbt
For example, xterm 256-colour mode is not supported at all.
Also, ipbt's Unicode support does not currently handle various Unicode complications such as characters
outside the Basic Multilingual Plane, double-width CJK characters, right-to-left scripts, or combining
characters.
(Patches or help from people who know how to persuade ncursesw to do any or all of those things would be
welcome!)
LICENCE
ipbt is free software, distributed under the MIT licence. Type ipbt --licence to see the full licence
text.
Simon Tatham 2007‐04‐19 ipbt(1)