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diff --git a/doc/asciicast-v1.md b/doc/asciicast-v1.md new file mode 100644 index 0000000..de55223 --- /dev/null +++ b/doc/asciicast-v1.md @@ -0,0 +1,64 @@ +# asciicast file format (version 1) + +asciicast file is JSON file containing meta-data like duration or title of the +recording, and the actual content printed to terminal's stdout during +recording. + +Version 1 of the format was used by the asciinema recorder versions 1.0 up to 1.4. + +## Attributes + +Every asciicast includes the following set of attributes: + +* `version` - set to 1, +* `width` - terminal width (number of columns), +* `height` - terminal height (number of rows), +* `duration` - total duration of asciicast as floating point number, +* `command` - command that was recorded, as given via `-c` option to `rec`, +* `title` - title of the asciicast, as given via `-t` option to `rec`, +* `env` - map of environment variables useful for debugging playback problems, +* `stdout` - array of "frames", see below. + +### Frame + +Frame represents an event of printing new data to terminal's stdout. It is a 2 +element array containing **delay** and **data**. + +**Delay** is the number of seconds that elapsed since the previous frame (or +since the beginning of the recording in case of the 1st frame) represented as +a floating point number, with microsecond precision. + +**Data** is a string containing the data that was printed to a terminal in a +given frame. It has to be valid, UTF-8 encoded JSON string as described in +[JSON RFC section 2.5](http://www.ietf.org/rfc/rfc4627.txt), with all +non-printable Unicode codepoints encoded as `\uXXXX`. + +For example, frame `[5.4321, "foo\rbar\u0007..."]` means there was 5 seconds of +inactivity between previous printing and printing of `foo\rbar\u0007...`. + +## Example asciicast + +A very short asciicast may look like this: + + { + "version": 1, + "width": 80, + "height": 24, + "duration": 1.515658, + "command": "/bin/zsh", + "title": "", + "env": { + "TERM": "xterm-256color", + "SHELL": "/bin/zsh" + }, + "stdout": [ + [ + 0.248848, + "\u001b[1;31mHello \u001b[32mWorld!\u001b[0m\n" + ], + [ + 1.001376, + "I am \rThis is on the next line." + ] + ] + } diff --git a/doc/asciicast-v2.md b/doc/asciicast-v2.md new file mode 100644 index 0000000..ff7dddb --- /dev/null +++ b/doc/asciicast-v2.md @@ -0,0 +1,183 @@ +# asciicast file format (version 2) + +asciicast v2 file is [newline-delimited JSON](http://jsonlines.org/) file where: + +* __first line__ contains header (initial terminal size, timestamp and other + meta-data), encoded as JSON object, +* __all following lines__ form an event stream, _each line_ representing a + separate event, encoded as 3-element JSON array. + +Example file: + +```json +{"version": 2, "width": 80, "height": 24, "timestamp": 1504467315, "title": "Demo", "env": {"TERM": "xterm-256color", "SHELL": "/bin/zsh"}} +[0.248848, "o", "\u001b[1;31mHello \u001b[32mWorld!\u001b[0m\n"] +[1.001376, "o", "That was ok\rThis is better."] +[2.143733, "o", " "] +[6.541828, "o", "Bye!"] +``` + +Suggested file extension is `.cast`, suggested media type is +`application/x-asciicast`. + +## Header + +asciicast header is JSON-encoded object containing recording meta-data. + +### Required header attributes: + +#### `version` + +Must be set to `2`. Integer. + +#### `width` + +Initial terminal width (number of columns). Integer. + +#### `height` + +Initial terminal height (number of rows). Integer. + +### Optional header attributes: + +#### `timestamp` + +Unix timestamp of the beginning of the recording session. Integer. + +#### `duration` + +Duration of the whole recording in seconds (when it's known upfront). Float. + +#### `idle_time_limit` + +Idle time limit, as given via `-i` option to `asciinema rec`. Float. + +This should be used by an asciicast player to reduce all terminal inactivity +(delays between frames) to maximum of `idle_time_limit` value. + +#### `command` + +Command that was recorded, as given via `-c` option to `asciinema rec`. String. + +#### `title` + +Title of the asciicast, as given via `-t` option to `asciinema rec`. String. + +#### `env` + +Map of captured environment variables. Object (String -> String). + +Example env: + +```json +"env": { + "SHELL": "/bin/bash", + "TERM": "xterm-256color" +} +``` + +> Official asciinema recorder captures only `SHELL` and `TERM` by default. All +> implementations of asciicast-compatible terminal recorder should not capture +> any additional environment variables unless explicitly permitted by the user. + +#### `theme` + +Color theme of the recorded terminal. Object, with the following attributes: + +- `fg` - normal text color, +- `bg` - normal background color, +- `palette` - list of 8 or 16 colors, separated by colon character. + +All colors are in the CSS `#rrggbb` format. + +Example theme: + +```json +"theme": { + "fg": "#d0d0d0", + "bg": "#212121", + "palette": "#151515:#ac4142:#7e8e50:#e5b567:#6c99bb:#9f4e85:#7dd6cf:#d0d0d0:#505050:#ac4142:#7e8e50:#e5b567:#6c99bb:#9f4e85:#7dd6cf:#f5f5f5" +} +``` + +> A specific technique of obtaining the colors from a terminal (using xrdb, +> requesting them from a terminal via special escape sequences etc) doesn't +> matter as long as the recorder can save it in the above format. + +## Event stream + +Each element of the event stream is a 3-tuple encoded as JSON array: + + [time, event-type, event-data] + +Where: + +* `time` (float) - indicates when this event happened, represented as the number + of seconds since the beginning of the recording session, +* `event-type` (string) - one of: `"o"`, `"i"`, +* `event-data` (any) - event specific data, described separately for each event + type. + +For example, let's look at the following line: + + [1.001376, "o", "Hello world"] + +It represents the event which: + +* happened 1.001376 sec after the start of the recording session, +* is of type `"o"` (print to stdout, see below), +* has data `"Hello world"`. + +### Supported event types + +This section describes the event types supported in asciicast v2 format. + +The list is open to extension, and new event types may be added in both the +current and future versions of the format. For example, we may add new event +type for text overlay (subtitles display). + +A tool which interprets the event stream (web/cli player, post-processor) should +ignore (or pass through) event types it doesn't understand or doesn't care +about. + +#### "o" - data written to stdout + +Event of type `"o"` represents printing new data to terminal's stdout. + +`event-data` is a string containing the data that was printed to a terminal. It +has to be valid, UTF-8 encoded JSON string as described +in [JSON RFC section 2.5](http://www.ietf.org/rfc/rfc4627.txt), with all +non-printable Unicode codepoints encoded as `\uXXXX`. + +#### "i" - data read from stdin + +Event of type `"i"` represents character(s) typed in by the user, or +more specifically, data sent from terminal emulator to stdin of the recorded +shell. + +`event-data` is a string containing the captured character(s). Like with `"o"` +event, it's UTF-8 encoded JSON string, with all non-printable Unicode codepoints +encoded as `\uXXXX`. + +> Official asciinema recorder doesn't capture stdin by default. All +> implementations of asciicast-compatible terminal recorder should not capture +> it either unless explicitly permitted by the user. + +## Notes on compatibility + +Version 2 of asciicast file format solves several problems which couldn't be +easily fixed in the old format: + +* minimal memory usage when recording and replaying arbitrarily long sessions - + disk space is the only limit, +* when the recording session is interrupted (computer crash, accidental close of + terminal window) you don't lose the whole recording, +* it's real-time streaming friendly. + +Due to file structure change (standard JSON => newline-delimited JSON) version 2 +is not backwards compatible with version 1. Support for v2 has been added in: + +* [asciinema terminal recorder](https://github.com/asciinema/asciinema) - 2.0.0 +* [asciinema web player](https://github.com/asciinema/asciinema-player) - 2.6.0 +* [asciinema server](https://github.com/asciinema/asciinema-server) - v20171105 + tag in git repository |