Free online PPSM to WEBM converter

A PPSM deck is a PowerPoint slide show, but many websites and players accept video rather than presentation files. Converting it to WEBM renders the slides as a video that can be shared or played without opening the deck.

What the PPSM format is

PPSM is the macro-enabled PowerPoint Open XML slide-show format, created by Microsoft PowerPoint. Opening one starts the presentation in slide-show mode; it can contain slide content, transitions, animations, media, and VBA macros. A video conversion renders the presentation, so the resulting file does not retain editable slides or executable macros.

What the WEBM format is

WEBM is a video container commonly used for browser playback and web embedding. It typically holds VP8 or VP9 video and Opus or Vorbis audio. It is useful when a recipient needs a playable video instead of a PowerPoint file, though some older players and editing applications may not support every WEBM codec.

How to convert PPSM to WEBM

Online on 101convert.com

1. Upload the PPSM file to the converter and choose WEBM as the output format.
2. If needed, set show each page for before starting the conversion. Multiple files can be added as a batch; the per-file size limit is shown on the page.
3. Start the conversion and download the resulting WEBM file.

Offline with desktop software

LibreOffice Impress and FFmpeg provide a free route on Windows, macOS, and Linux for making a video from static slide pages. Install LibreOffice and FFmpeg; the PDF-to-image step also requires Poppler’s pdftoppm. In a working folder, convert the presentation to PDF, render its pages to PNG, then encode them as WEBM:

1. Run libreoffice --headless --convert-to pdf --outdir render deck.ppsm, replacing deck.ppsm with the input filename.
2. Run pdftoppm -png -r 150 render/deck.pdf render/slide to create numbered slide images.
3. Run ffmpeg -framerate 1/5 -start_number 1 -i render/slide-%d.png -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -r 30 -c:v libvpx-vp9 -crf 32 -b:v 0 -an output.webm. This holds each page for five seconds; change 1/5 to adjust the interval.

Microsoft PowerPoint and FFmpeg retain the rendered transitions and timing more reliably. In PowerPoint, open the PPSM and use File → Export → Create a Video to save an MP4. Then convert it with ffmpeg -i presentation.mp4 -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus output.webm. Replace presentation.mp4 with the exported filename. PowerPoint’s video-export options vary by version.

Quality and limitations

The LibreOffice PDF route produces still pages, not slide animations, timed transitions, narration, or embedded video playback. The PowerPoint route can render timings and effects, but the final result is still a flattened video: slide text and objects cannot be edited separately, and PPSM macros are not carried into WEBM. Lower FFmpeg CRF values generally increase VP9 quality and file size.