Free online OGM to ASF converter

What the OGM format is

OGM, or Ogg Media, is an Ogg-based multimedia container used mainly for video files with codecs such as Xvid, DivX, MPEG-4 Part 2, Vorbis, and occasionally other audio formats. It was common in older video releases because it could hold multiple audio tracks, subtitles, and chapters in one file.

OGM files are created or muxed by tools such as OGMmerge, VirtualDubMod, and older versions of FFmpeg. You may encounter them in archived video collections, older computer downloads, or files intended for playback in VLC and other software with Ogg Media support.

What the ASF format is

ASF, or Advanced Systems Format, is a Microsoft container designed for streamed and downloadable audio and video. It commonly carries Windows Media Video and Windows Media Audio streams and uses the .asf extension; files using WMV video are also frequently distributed with the .wmv extension.

ASF provides packetized playback, timestamps, metadata, and support for network delivery. It is useful when a legacy Windows application, media server, or hardware player specifically requires ASF or Windows Media-compatible streams. It is less suitable than newer containers for modern editing, subtitles, and broad device compatibility.

How to actually convert OGM to ASF

Using the online converter

You can convert the file on 101convert.com for free without installing software. Select the OGM input, choose ASF as the output format, start the conversion, and download the resulting file. The service is most convenient when you do not need custom codec, bitrate, stream-selection, or subtitle settings.

Using FFmpeg on a computer

FFmpeg is the most controllable desktop option. First inspect the streams:

ffprobe -hide_banner input.ogm

If the existing codecs are accepted by the target ASF player, test a stream copy to avoid quality loss:

ffmpeg -i input.ogm -map 0:v:0 -map 0:a:0? -c copy -f asf output.asf

Stream copying is not guaranteed to work because OGM codecs, subtitle streams, and codec-specific metadata may not be supported by the ASF muxer or playback software. If it fails, or if the target program expects Windows Media codecs, re-encode:

ffmpeg -i input.ogm -map 0:v:0 -map 0:a:0? -sn -c:v msmpeg4v3 -b:v 1500k -pix_fmt yuv420p -c:a wmav2 -b:a 128k -ar 44100 -f asf output.asf

msmpeg4v3 and wmav2 provide broad compatibility with older ASF software. Adjust -b:v to the source resolution and desired file size; increasing it preserves more detail but produces a larger file. Use -map 0:a:1 instead of -map 0:a:0? to select a second audio track.

For a Windows Media Video 9 workflow, check whether the installed FFmpeg build exposes a suitable encoder with ffmpeg -encoders. Encoder availability varies by build, and an ASF extension alone does not make a file compatible with every Windows Media player.

Quality, compatibility, and limitations

Re-encoding from OGM to ASF reduces quality because the video and usually the audio are compressed again. Stream copying avoids that loss, but only works when the source streams and the target player support the selected ASF combination.

OGM subtitles and chapter information are commonly lost during ASF conversion. The example deliberately uses -sn because ASF playback support for embedded subtitles is inconsistent; render subtitles into the video beforehand if they must appear on every player.

Check the finished file with:

ffprobe -hide_banner output.asf

Verify that the video codec, audio codec, duration, frame size, and audio synchronization match the requirements of the receiving application. ASF is a legacy format, so MP4 is usually a better choice when the software does not explicitly require ASF.