Free online PPTX to WEBM converter

A presentation may need to be delivered as a video for playback in a browser, on a device that does not have presentation software, or on a platform that accepts WEBM. Converting it renders the slides into timed video frames rather than leaving them as editable slides.

What PPTX is

PPTX is the Office Open XML presentation format used by Microsoft PowerPoint and supported by programs such as LibreOffice Impress. It stores slides, text, images, charts, animations, transitions, and sometimes audio or video; it is commonly shared as an editable slide deck.

What WEBM is

WEBM is a video container commonly used for web playback. It typically contains VP8 or VP9 video and may contain Opus or Vorbis audio; its browser-oriented formats can be useful for embedding a presentation video on a website. A WEBM file is a rendered video, not an editable slide deck.

How to convert PPTX to WEBM

Online on 101convert.com

1. Upload the PPTX file on the converter page. You can add several files for batch conversion; each file is subject to the size limit shown on the page.
2. Set show each page for to choose how long each slide is displayed.
3. Start the conversion and download the WEBM file when it is ready.

Offline with desktop software

Free, open-source route on Linux: use LibreOffice to render the deck as PDF, Poppler’s pdftoppm to create slide images, and FFmpeg to encode them as WEBM. For a deck named deck.pptx, run:

1. libreoffice --headless --convert-to pdf --outdir /tmp deck.pptx
2. pdftoppm -png -r 150 /tmp/deck.pdf /tmp/slide
3. Create a text file named slides.txt listing the images in order, with a duration after each one. For example: file '/tmp/slide-1.png', then duration 5, then file '/tmp/slide-2.png', then duration 5. Add the final image filename again at the end of the list.
4. Encode the list with ffmpeg -f concat -safe 0 -i slides.txt -vsync vfr -c:v libvpx-vp9 -crf 32 -b:v 0 -pix_fmt yuv420p output.webm.

This route makes a video from static slide images; it does not preserve PowerPoint animations, transitions, narration, or embedded video. Use equal-size images and adjust the duration entries to set slide timing.

Microsoft PowerPoint: on desktop versions with video export, open the presentation and choose File → Export → Create a Video. Set the resolution and recorded timings or the time per slide, then export as MP4. Convert that file with FFmpeg: ffmpeg -i presentation.mp4 -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus presentation.webm. If the MP4 has no audio, use -an instead of -c:a libopus.

Quality and compatibility

Slide timing, animation, transitions, and audio depend on the export method: the PDF-and-image workflow omits motion and sound, while PowerPoint’s video export can use recorded timings and narration. Lower CRF values generally produce higher-quality, larger VP9 files; check the result in the target browser or player, especially if it needs to play audio.