MPEG to ASF Converter

MPEG vs ASF — Which Container Do You Actually Need?

Both .mpeg and .asf are containers, not codecs, and the choice between them is almost never about quality. An .mpeg is an MPEG program stream — the DVD, VCD and broadcast-capture format, typically MPEG-2 video (standardised as ITU-T H.262, first approved July 1995) with MP2 audio. ASF is Microsoft's Advanced Systems Format, built for synchronized streams served over a network. Short answer: stay on MPEG for disc authoring and general playback; convert to ASF only when a Windows Media server, a Windows Media Format pipeline, or software that filters on the .asf extension leaves you no choice.

Side-by-side: .mpeg vs .asf

When to Stay on MPEG

• You are authoring or restoring a DVD/VCD, where the program stream is the deliverable.
• The file is an archive master. MPEG-2 program streams open in essentially every desktop player and editor without a codec pack.
• Playback targets are mixed — phones, TVs, browsers. ASF gets you nothing there, and MP4 gets you everything: use MPEG to MP4.
• You only want a smaller file. Re-containering does not compress; use compress MPEG or a modern codec instead.

When to Convert to ASF

• A Windows Media server or an in-house tool accepts .asf and rejects everything else.
• You are feeding legacy Windows Media tooling that expects Windows Media Video and Windows Media Audio payloads — in which case set the Video Codec to WMV, since ASF here defaults to H.264.
• You need one container holding several synchronized streams — multiple audio tracks, script commands, text streams — under Microsoft's object model.
• A validator checks the extension and container signature rather than the codec inside.

How to Convert MPEG to ASF

1. Upload Your MPEG File: Drag and drop your .mpeg or .mpg, or click "Add Files". Both extensions are accepted and several clips can be queued and converted with the same settings.
2. Choose the Video Codec and Audio Codec: "Video Codec" defaults to H.264 and "Audio Codec" to WMA v2. Switch Video Codec to "WMV 2" (or "WMV 1") if the destination is legacy Windows Media tooling — this is the setting that decides compatibility, not the extension.
3. Pick a File Compression Mode: "File Compression" starts on "Quality Preset" with "Very High (Recommended)" selected. "Specific file size", "Constant Bitrate", "Variable Bitrate", "Constant Quality" and "Constraint Quality" are the alternatives; "Video resolution" starts on "Keep original", and "Trim" can take a Start time and Duration.
4. Convert and Download: Click Convert. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours — no sign-up, no watermark, never shared.

Which Codec Goes Inside the ASF

The container is codec-agnostic, so the payload is the whole decision. The Video Codec dropdown offers twenty entries here, including H.264, MPEG-4, MPEG-2, Xvid, DivX, VP8, VP9, AV1, Theora, MJPEG, the H.26x family and MS MPEG-4 — but only three of them are Windows Media codecs.

Note the trade-off on the WMV path: WMV 1 and WMV 2 do not support CRF encoding. Selecting one re-ranges the "Constant Quality" and "Constraint Quality" number from the 16-51 CRF scale to a 1-31 qscale — where lower is better and the scale is far more aggressive — while the field keeps its "CRF" label. On a 10-second 720p clip we measured 23.5 MB at q2 against 2.28 MB at q23, so an x264-style "23" is not a mid-range setting here; it is close to the bottom of the quality range. If you want predictable output on WMV, use "Constraint Quality" with an explicit Max bitrate, or "Variable Bitrate".

Frequently Asked Questions

Does the ASF output contain WMV video by default?

No — and this surprises most people. The Video Codec dropdown on this page defaults to H.264, with WMA v2 audio. That produces a valid, efficient .asf that ffmpeg-based players open happily, but it is not what a legacy Windows Media stack expects. For that, change Video Codec to "WMV 2" before converting; the audio default is already correct.

Is converting MPEG to ASF lossless, or does the video get re-encoded?

The video is always re-encoded. The source carries MPEG-1 or MPEG-2 video and the ASF will carry H.264 or WMV, so there is no stream-copy path between them — our server decodes and re-encodes every time. Use the "Very High (Recommended)" preset, or "Constant Quality" with a low CRF, to keep generation loss down.

Can an ASF hold more than one audio track from my program stream?

The container can. Microsoft describes ASF as holding "multiple independent or dependent streams, including multiple audio streams for multichannel audio," alongside text streams, web pages and script commands. What survives the transcode is a different question: our pipeline re-encodes the streams it demuxes, and private-stream data such as embedded DVD subtitles is not carried into ASF.

Why does my ASF come out larger than the MPEG I started with?

Usually because the Quality Preset is doing what it is told. On codecs without CRF support — which includes WMV 1 and WMV 2 — the preset scales the source bitrate, and the "Very High" level targets more than the original. If your MPEG-2 was already high-bitrate, the WMV re-encode can exceed it. Switch to "Specific file size", "Variable Bitrate", or a lower preset if size matters.

Will the interlacing from my DVD capture be cleaned up?

No. Most DVD and broadcast MPEG-2 is interlaced, and we do not deinterlace anywhere in the pipeline — the field combing is re-encoded into the ASF as picture content. If the combing matters, deinterlace in a desktop editor before uploading.

My 16:9 DVD rip looks squashed after conversion. Why?

Anamorphic DVD material stores widescreen content in a 720×576 or 720×480 frame using non-square pixels, and the pixel aspect ratio is normalised to square during conversion rather than corrected. Fix it explicitly: under "Video resolution", choose "Width x Height" and enter the intended display size, for example 1024×576 for 16:9 PAL content.

Is ASF a dead format I should be migrating away from?

It still plays on current Windows, but Microsoft has flagged the Windows Media Format 11 SDK as a legacy feature superseded by Source Reader and Sink Writer in Media Foundation, and recommends new code use the newer APIs. Treat ASF as a compatibility target rather than an archive format. If you inherit .asf files and want them future-proof, ASF to MP4 is the migration path.

What happens to my file after the conversion finishes?

It uploads over an encrypted connection, converts on our servers, and both the source and the generated .asf are deleted automatically after a few hours. There is no account, no watermark on the output, and files are never shared or made public. The practical ceiling on a long DVD rip is upload size and time rather than anything in the encode itself.