Convert WMV to HEVC — Free Online Tool
Convert WMV files to HEVC (.hevc) directly in your browser, re-encoding the legacy Microsoft MPEG-4 video stream with the libx265 encoder for dramatically smaller file sizes at equivalent visual quality. HEVC's superior compression makes it ideal for archiving or repurposing older Windows Media content without wasting storage.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
WMV files use Microsoft's proprietary ASF container with video encoded in MS-MPEG-4 (msmpeg4 or msmpeg4v2) — a codec unrelated to standard MPEG-4 and not natively supported by most modern players outside of Windows. During this conversion, FFmpeg fully decodes the MS-MPEG-4 video stream and re-encodes every frame using libx265, the reference H.265/HEVC encoder. This is a full transcoding operation, not a remux — the pixel data is decompressed from the WMV bitstream and recompressed using HEVC's advanced prediction and entropy coding tools. The WMV audio track (typically WMA v2) is not mapped to the output, since the raw .hevc elementary stream format carries video only. The result is a standalone HEVC bitstream that typically achieves 40–50% smaller file size compared to an equivalent-quality H.264 encode of the same source.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia framework, which handles decoding the proprietary ASF/MS-MPEG-4 WMV bitstream and re-encoding it to HEVC using the libx265 library. |
-i input.wmv
|
Specifies the input WMV file. FFmpeg automatically detects the ASF container and the MS-MPEG-4 video codec (and WMA audio, if present) from the file's headers. |
-c:v libx265
|
Selects libx265 as the video encoder, which implements the H.265/HEVC standard. This replaces the legacy MS-MPEG-4 encoding from the WMV source with a modern, far more efficient codec. |
-crf 28
|
Sets the Constant Rate Factor for libx265 to 28, controlling the quality-to-filesize tradeoff. Lower values produce higher quality at larger file sizes; 28 is the libx265 default and delivers good compression for most archived WMV content. |
-x265-params log-level=error
|
Passes the log-level=error parameter directly to the libx265 encoder, suppressing its verbose per-frame encoding statistics and keeping output readable without affecting the quality or content of the encoded HEVC stream. |
output.hevc
|
Specifies the output file as a raw HEVC elementary stream. This format contains only the re-encoded video — no audio, no metadata, and no container wrapper — which is appropriate for HEVC streams intended for further muxing or analysis. |
Common Use Cases
- Archiving old corporate training videos or screen recordings originally saved as WMV, dramatically reducing storage footprint while preserving visual quality for long-term retention.
- Repurposing WMV footage captured by older Windows-based security camera systems into a modern HEVC stream compatible with professional video editing pipelines.
- Stripping out the proprietary Microsoft ASF wrapper and MS-MPEG-4 encoding from WMV files destined for ingest into HEVC-capable hardware encoders or transcoding servers.
- Preparing legacy Windows Media content for playback on Apple devices or smart TVs that natively decode HEVC but refuse to play MS-MPEG-4 encoded WMV files.
- Reducing bandwidth requirements when re-streaming archived WMV conference recordings, since HEVC delivers comparable quality to the original at roughly half the bitrate.
- Generating a raw HEVC elementary stream from a WMV source for researchers or developers testing HEVC decoders, muxers, or quality-analysis tools.
Frequently Asked Questions
The raw .hevc elementary stream format is a video-only container — it cannot carry audio tracks. Your WMV file's WMA audio is intentionally not included in the output because the .hevc format has nowhere to store it. If you need to preserve the audio, consider converting to a container like MKV or MP4 using H.265 video instead, which can hold both the HEVC video stream and an audio track simultaneously.
Because WMV uses a lossy codec (MS-MPEG-4), your source file has already undergone one round of quality reduction. Re-encoding to HEVC introduces a second generation of lossy compression, so some additional quality loss is mathematically unavoidable. However, the default CRF 28 setting targets a perceptually efficient quality level, and HEVC's superior compression algorithms often produce a result that looks visually similar to the WMV source at a much lower bitrate. For the best results, use a lower CRF value (e.g., 18–23) if your source WMV was high quality.
HEVC typically delivers 40–50% better compression than older codecs like MS-MPEG-4 at equivalent visual quality, so the output .hevc file is usually substantially smaller than the source WMV. The exact reduction depends heavily on the content: high-motion footage like sports will see a more modest reduction, while talking-head videos or static screen recordings can shrink dramatically. The CRF 28 default balances quality and size well for most archival use cases.
No. WMV supports Microsoft's DRM (Digital Rights Management) protection, and DRM-protected WMV files cannot be decoded or converted by FFmpeg — or any standard tool — without the appropriate license key. FFmpeg will typically produce an error or an empty output when it encounters a protected ASF stream. Only WMV files you own and that are not DRM-restricted can be converted with this tool.
The quality is controlled by the -crf flag, which accepts values from 0 (lossless) to 51 (lowest quality). The default value of 28 is a reasonable balance for most content. To increase quality and produce a larger file, lower the CRF — for example, use '-crf 18' for near-transparent quality. To prioritize a smaller file at the cost of some sharpness, raise it — for example, '-crf 35'. Each increment of roughly 6 CRF units approximately halves or doubles the output bitrate.
Yes. On Linux or macOS, you can wrap the command in a shell loop: 'for f in *.wmv; do ffmpeg -i "$f" -c:v libx265 -crf 28 -x265-params log-level=error "${f%.wmv}.hevc"; done'. On Windows Command Prompt, use: 'for %f in (*.wmv) do ffmpeg -i "%f" -c:v libx265 -crf 28 -x265-params log-level=error "%~nf.hevc"'. Note that the browser-based tool processes one file at a time; the FFmpeg command is the recommended approach for batch processing large collections of WMV files.
Technical Notes
The WMV format uses Microsoft's Advanced Systems Format (ASF) container with video encoded in MS-MPEG-4 v2 or v3 — a proprietary variant of MPEG-4 Part 2 that diverges significantly from the ISO standard and is not interchangeable with DivX, Xvid, or other MPEG-4 implementations. FFmpeg must fully decode this non-standard bitstream before re-encoding to HEVC, making this a computationally intensive conversion. The output is a raw HEVC elementary stream (.hevc), which lacks a container wrapper — it carries no audio, no metadata (title, creation date, etc.), and no chapter markers. Because WMV files can embed WMA audio at variable bitrates and optionally carry multiple audio streams, all of this is discarded in the conversion to a bare HEVC stream. The -x265-params log-level=error flag suppresses libx265's verbose per-frame encoding statistics, keeping console output clean without affecting the encoded video. HEVC supports HDR (HDR10, HLG), 4K, and 8K content, but WMV sources are typically SD or HD with standard dynamic range, so these capabilities are relevant only if your WMV source contains HDR-flagged content, which is exceedingly rare. Files processed by this tool stay entirely within your browser via FFmpeg.wasm — no data is transmitted to a server.