Export demo to video

[mikota]

This is a feature request to add support for exporting demo files (or specific parts of a demo) into a video file with an arbitrary framerate.

Motivation

This feature is beneficial over just recording gameplay via external software (OBS, NVIDIA shadowplay, etc) because of many concerns, such as quality & convenience, but most of all, the ability to capture demos in high framerates. This is important because high framerate (eg. 1000+fps) recordings are used to apply frameblending motion-blur which is crucial to the viewing experience when the final video is capped to 60fps which is the case on most video-sharing sites. It is even more important when the final video is capped to 30fps, due to artistic choice, or due to technical limitations. For example, for the AQ2Open 2023 LAN in Stockholm, we had to produce a 30fps video for the videowall shown in the venue due to them not supporting anything higher (this is not uncommon).

This technique has been used since the mid 2000's in Quake and Goldsrc fragmovies (eg. q3, cs1.6, rtcw: et), and has since the early 2010's become a staple of the medium. It is crucial for fragmovies and would be useful for q2jump as other movement-focused communities use it to amplify the viewing experience (eg. defrag, 1.6 surf, source surf).

Technical

Exporting demos to video is supported by FTE, Darkplaces, as well as most Q3 engines. It is also supported by AprQ2 (client manual, source?).

Usually this feature is implemented either as exporting to imagesequence, pre-defined videoformat, or a configurable ffmpeg setup. If basic imagesequence is the only option available, usually a separate soundfile is generated alongside the imageseq for the gameaudio.

Finally, to address the elephant in the room, it is possible to achieve this in q2pro right now by using timescale. For example, recording in OBS with 60fps and timescale 0.05 gives you a 1200fps recording. This is how I do all of my video projects in q2pro, however, it has a myriad of problems, such as quality, low timescale weirdness, and needing a second recording for sound, but the biggest one being the time it takes to record - a twelve second clip takes 4 minutes to record. This is simply not feasable for longform videos.

Thanks for all the work on q2pro and please add this feature.

[zhprzq2]

For example, recording in OBS with 60fps and timescale 0.05 gives you a 1200fps recording.

Did you mean 120?

[mikota]

For example, recording in OBS with 60fps and timescale 0.05 gives you a 1200fps recording.

Did you mean 120?

No.