Free online MPEG to WEBM converter

A browser, HTML5 player, or web-publishing system may require WebM instead of an older MPEG file. Converting also creates a web-oriented copy, but it re-encodes the video unless the source already contains WebM-compatible streams.

What the MPEG format is

MPEG describes a family of compression standards and commonly refers to files with .mpg or .mpeg extensions. These files often contain MPEG-1 or MPEG-2 video with MP2 or MP3 audio. DVD authoring tools, digital television equipment, camcorders, screen-recording applications, and older video editors commonly use MPEG.

The extension does not identify one exact codec or container. Inspect the file's video and audio streams before choosing conversion settings, especially when it contains MPEG-4 video, unusual audio, subtitles, or multiple tracks.

What the WebM format is

WebM is a Matroska-based container designed primarily for web video. Common combinations include VP8, VP9, or AV1 video with Vorbis or Opus audio. Current Chromium-based browsers, Firefox, and recent Safari versions can play WebM, although support varies by operating system, codec, audio stream, and hardware.

WebM is useful for browser playback and web publishing because its codecs are open and its encoding options can produce smaller files than older MPEG-1 or MPEG-2 encodings at comparable visual quality. It is less suitable as the only copy for older televisions, DVD software, legacy editors, or devices that expect MPEG or H.264 in an MP4 container.

How to convert an MPEG file to WebM

For a conversion without installing software, use the converter on 101convert.com: upload the .mpg or .mpeg file, choose WebM as the output format, start the conversion, and download the resulting .webm file. Review the output in the target browser or player before replacing the source.

For local processing and detailed control, FFmpeg is the most flexible option. Open a terminal in the source folder and run:

ffmpeg -i input.mpg -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus -b:a 96k output.webm

This command re-encodes the video with VP9 in constant-quality mode and the audio with Opus. For VP9, lower -crf values produce higher quality and larger files; values around 30–36 are a practical starting range. Try -crf 28 for a higher-quality copy or -crf 36 for a smaller copy, then inspect the result.

The command keeps the input dimensions and frame rate unless FFmpeg must convert them for codec compatibility. To limit a large source to 720 pixels high while preserving its aspect ratio, add a scale filter:

ffmpeg -i input.mpeg -vf "scale=-2:720" -c:v libvpx-vp9 -crf 32 -b:v 0 -c:a libopus -b:a 96k output.webm

scale=-2:720 calculates an even width, which avoids a common encoder restriction. Use ffmpeg -encoders to check that the installed build includes libvpx-vp9 and libopus. If the source has several audio or subtitle tracks, specify the required streams explicitly; WebM does not support every MPEG-era stream type or subtitle format.

Quality and compatibility limits

Most conversions decode and re-encode both streams, so they cannot restore lost detail and may introduce additional quality loss. Keep the original MPEG as the archival master and avoid converting an already compressed copy repeatedly.

WebM is not guaranteed to be smaller. High-quality VP9 or AV1 encoding can take considerably longer than MPEG encoding, and a short or heavily compressed source may produce a file of similar or greater size. Test seeking, audio, subtitles, frame rate, and playback on the actual browser, device, or publishing system. Keep an MP4 file using H.264 and AAC as an additional delivery copy when older hardware or editing software must be supported.