Caching / Pre-rendering

To allow fast changes between the different slides of the presentation the PDF pages are pre-rendered to memory. The progress bar on the bottom of the presenter screen indicates how many percent of the slides have been pre-rendered already. During the initial rendering phase this will slow down slide changes, as most CPU power is used for the rendering process in the background. After the cache is fully primed, however, the changing of slides should be much faster, as with normal PDF viewers.

As the pre-rendering takes a lot of memory it can be disabled using the --disable-cache switch at the cost of speed.

It it also possible to store the pre-rendered slides on the disk (see --persist-cache). This speeds up the start of the program if the slide set is used next time unchanged.

Cache compression

The pre-rendered and cached slides can be compressed in memory to save up some memory. Without compression a set of about 100 PDF pages can easily grow up to about 1.5 GB size. Netbooks with only 1 GB of memory would swap heavily if pre-rendering is enabled in such a situation. The compression is enabled by default as it does not harm rendering speed in a noticeable way on most systems. It does, however, slow down pre-rendering by about a factor of two. If you have got enough memory and want to ensure the fastest possible pre-rendering you can disable slide compression by using the -z switch. But be warned that using the uncompressed pre-rendering storage will use about 30 times the memory the new compressed storage utilizes (e.g. 50 MB will become about 1.5 GB).

Timer

If a duration is given (-d option), the timer will show a countdown with the given parameters. If no duration is specified (or if a value of 0 is given to the -d option), the timer will show how much time has been spent. The duration is stored automatically, so you do not need to repeat it for every invocation.

The timer is started if you are navigating away from the first page for the first time. This feature is quite useful as you may want to show the title page of your presentation while people are still entering the room and the presentation has not really begun yet. If you want to start over you can use the 'r' key which will make the presenter reset the timer.

If a duration is given, the timer also provides hints aiding the presenter to judge whether the talk would end on time. There are two modes in which pdfpc can operate. In the old (and the only one available up to, and including pdfpc-4.0.8) mode, at the moment the timer reaches the defined last-minutes value it will change color to indicate your talk is nearing its end, thus mimicking a chairman frantically pantomiming in front of you with five (four, three, ...) fingers up. A drawback of this approach is it is often too late at that moment to alter the presentation pace without ruining to some extent the rest of the talk. On the other hand, the warning indication provides an unnecessary distraction if you have been perfectly conveying the talk and the remaining time is adequate.

Contrary to that, in the new (default) mode, pdfpc tracks your progress continuously, calculating the expected time as (talk_duration)*(current_user_slide_number - 0.5)/(total_number_of_user_slides) and comparing it to the actual wall time since beginning of the talk. If these two numbers differ by more than 60 seconds, the timer changes its color to either orange (indicating you need to speed up) or a blueish one (need to slow down). Once the optimal progress is recovered, the timer becomes white again. In this mode, the last-minutes option (-l) has no effect. The previous behavior can be restored by setting the 'timer-pace-color' option to 'false' in the configuration file, see pdfpcrc(5).

In any case as soon as the timer reaches the zero mark (00:00:00), it will turn red and count further down showing a negative time, to provide information on how many minutes you are overtime.

Notes

Textual notes can be displayed for each slide. A few types of PDF annotations are understood by pdfpc and will be automatically imported and displayed (only their textual content, no formatting attributes are preserved). The PDF annotations can be made using many PDF editors and even viewers. These "native" PDF notes cannot be edited in pdfpc.

In addition, while in the presentation mode, pressing 'n' will allow you to take notes for the current user slide. To exit the note editing mode, press the Escape key. Note that while editing a note, the keybindings stop working, i.e. you are not able to change slides. These notes are stored in the .pdfpc file in a plain text format, easy to edit also from outside the program; see the section about the pdfpc format below. These notes take precedence over the native PDF annotations, i.e., if a user-proveded note exists for a given slide, any PDF annotations on that page will be silently ignored.

Although mixing the two types of notes is possible, for a given presentation one will likely want to have either only the "native" notes (produced by the same PDF authoring software used for making the slides), or only the "pdfpc" ones.

Overview mode

Pressing the Tab key enters the overview mode, where thumbnails of the slides are shown in a grid. You can select a slide to jump to with the mouse or with the arrow keys. You can also define overlays and the end slide (see next sections) in this mode.

Overlays

Many slide preparation systems allow for overlays, i.e. sets of slides that are logically grouped together as a single, changing slide. Examples include enumerations where bullet items are displayed one after another, or rough "animations", where parts of a picture change from slide to slide. Pdfpc includes facilities for dealing with such overlays.

In this description, we will differentiate between slides (i.e. pages in the PDF document) and "user slides", that are the logical slides. The standard forward movement command (page down, enter, etc.) moves through one slide at a time, as expected. This means that every step in the overlay is traversed. The backward movement command works differently depending on whether the current and previous slides are part of an overlay:

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If the current slide is part of an overlay we just jump to the previous slide. That means that we are in the middle of an overlay and can jump forward and backward through the single steps of it

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If the current slide is not part of an overlay (or if it is the first one), but the previous slides are, we jump to the previous user slide. This means that when going back in the presentation you do not have to go through every step of the overlay, pdfpc just shows the first slide of each overlay. As one typically goes back in a presentation only when looking for a concrete slide, this is more convenient.

The up and down cursor keys work on the "user slide" basis. You can use them to skip the rest of an overlay or to jump to the previous user slide, ignoring the state of the current slide.

When going through an overlay, two additional previews may be activated in the presenter view, just below the main view, showing the next and the previous slide in an overlay.

Pdfpc tries to find these overlays automatically by looking into the page labels in the PDF file. For LaTeX this works correctly at least with the beamer class and also modifying the page numbers manually (compiling with pdflatex). If your preferred slide-producing method does not work correctly with this detection, you can supply this information using the 'o' key for each slide that is part of an overlay (except the first one!). The page numbering is also adapted. This information is automatically stored.

End slide

Some people like to have some additional, backup slides after the last slide in the actual presentation. Things like bibliographic references or slides referring to specialized questions are typical examples. Pdfpc lets you define which is the last slide in the actual presentation via the 'e' key. This just changes the progress display in the presenter screen, as to have a better overview of how many slides are left.

Movies

Pdfpc can play back movies included in the PDF file. Movies may be started and stopped by clicking within their area. For the presenter, a progress bar is drawn along the bottom of the movie. This expands when the mouse hovers over it, allowing one to seek by clicking or dragging within the progress bar. Switching slides automatically stops playback, and movies will be reset after leaving and returning to a slide.

Movies may be included in PDF files as "screen annotations". pdfpc does not yet support options that modify the playback of these movies. In LaTeX, such movies may be added to a presentation with the "movie15" or "multimedia" package. Note that the poster, autoplay, and repeat options are not yet supported. (Also, run ps2pdf with the -dNOSAFER flag.)

As a perhaps simpler option, pdfpc will play back movies linked from a hyperlink of type "launch". A query string may be added to the URL of the movie to enable the "autostart", "loop" and "noprogress" properties, if necessary. (E.g., a link to "movie.avi?autostart&loop&noprogress" will add a video that starts playing automatically, loops when it reaches the end, and does not show the progress bar.)

In LaTeX, such links are created with

The movie will playback in the area taken by the placeholder content. Using a frame of the movie will ensure the correct aspect ratio.

See our website ⟨URL: http://pdfpc.github.io/demo/pdfpc-video-example.zip ⟩ for a full example.

See the bugs section for further information.

Pointer mode

If needed, it is possible to turn on a pointer which draws a red dot in the place pointed by mouse cursor on both - presenter and presentation screens. It is also possible to increase and decrease the pointer size. Additionally, when the pointer is enabled, it is possible to highlight some area of the current slide using the drag mouse motion. The area outside the selected region will be dimmed.

Drawing mode

It is possible to turn on a mode which allows drawing over slides with the mouse cursor or a connected tablet. When drawing mode is enabled, drawings can be made on the presenter screen. A separate drawing will be kept in memory for each slide (based on user slide numbers, so consolidating overlay slides). Drawings are presently not saved between sessions.

In the drawing mode, there are two drawing tools, a pen and an eraser. An indicator in the bottom-left corner of the presenter screen will indicate which is active. When in the pen mode, the color and size of the pen will be indicated by the cursor. The pen size can be increased or decreased using hot keys specified in the key bindings. When the eraser tool is active, the size of the cursor indicates the amount to erase.

The color of the pen can be changed through key or mouse bindings.

If you are using a tablet, the pen or eraser tool will be selected based on whether the tablet reports a pen or eraser input device is being used, overriding the normal selection of the drawing tool.

pdfpc files

Some additional information is stored in a file with the extension "pdfpc". When pdfpc is invoked with a PDF file, it automatically checks for and loads the associated .pdfpc file, if it exists. This means that you normally do not have to deal with this kind of files explicitly.

Beside internal configuration, the following command-line options are stored within the pdfpc file for later usage:

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duration

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end_time

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last_minutes

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notes (position)

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start_time

There are, however, cases where you may want to edit this file manually. The most typical case is if you add or remove some slides after you have edited notes or defined overlays. It may be quicker to edit the pdfpc file than to re-enter the whole information.

There is also the possibility of including notes from a different file. If pdfpc encounters a [notes_include] section with the .pdfpc file it reads the notes only from the included file. Changing notes within pdfpc is then forbidden.

The files are plain-text files that should be fairly self-explanatory. A couple of things to note:

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The slide numbers of the notes refer to user slides

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Slide indexes start at 1

Appearance

With GTK3 it is possible to modify the appearance of pdfpc. There are two locations where pdfpc is looking for files. The default location is /usr/share/pixmaps/pdfpc/pdfpc.css. It can be copied to $XDG_CONFIG_HOME/pdfpc/pdfpc.css and modified to the user's liking.

Desktop integration

Pdfpc provides a DBus interface that appears on the session bus as io.github.pdfpc. Other applications can, in particular, execute any action listed by --list-actions. It is also possible to control pdfpc from the command line (and write shell scripts) using the dbus-send(1) utility. For example, to advance to the next slide, run

dbus-send --type=method_call --session --dest=io.github.pdfpc
/io/github/pdfpc io.github.pdfpc.TriggerAction string:next

In addition to the TriggerAction method, the pdfpc DBus interface exposes the GetNotes method, three properties (NumberOfOverlays, NumberOfSlides, Url) and two signals (OverlayChange and SlideChange).