Trin 1: Upload din WebM filer ved hjælp af knappen ovenfor eller ved at trække og slippe.
Trin 2: Klik på knappen 'Konverter' for at starte konverteringen.
Trin 3: Download din konverterede fil MP4 filer
WebM til MP4 Ofte stillede spørgsmål om konvertering
How do I re-encode WebM to MP4 without quality loss?
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Upload the WebM file and our converter applies a CRF-based re-encode targeting visually-lossless MP4 output (CRF 18 by default, lower = larger / higher quality). The codec is chosen to match the MP4 container — H.264 / H.265 / VP9 / AV1 as appropriate.
Which codec does the MP4 output use?
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It depends on the container. MP4 defaults to H.264 (broadest playback support); MKV defaults to H.265 for ~50% smaller file at the same quality; WebM defaults to VP9 or AV1 (royalty-free web streaming). You can override the codec choice in the advanced options before MP4 conversion runs.
Will my audio track survive WebM to MP4?
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Yes — audio is re-muxed when WebM and MP4 share an audio codec, or re-encoded to AAC / Opus / Vorbis depending on what the MP4 container supports. Multi-track audio (commentary, alternate languages) is preserved in containers that support it (MKV, WebM, MP4).
Can I keep the original framerate going from WebM to MP4?
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By default framerate is unchanged (WebM 24fps stays 24fps in MP4). If you need to change it (e.g. interlaced 29.97 to progressive 30fps) the framerate option handles 3:2 pulldown and deinterlacing in the same pass — no second decode required.
What is the file size difference between WebM and MP4?
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Same-codec re-muxes (H.264 in both WebM and MP4) produce nearly-identical sizes. Codec changes can swing things dramatically: H.264 -> H.265 typically halves the file at the same visual quality; H.264 -> VP9 is roughly comparable; AV1 is currently the smallest at the cost of slower encode time.
Will the MP4 file play on iPhone / Android / Smart TV?
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MP4 / H.264 plays everywhere natively. MOV / H.264 plays on Apple devices and most Smart TVs but not on older Android. MKV needs VLC on iOS. WebM plays in browsers but not most Smart TV apps. The "device compatibility" preset in advanced options picks the safest codec / container for your target.
How long does converting a 1-hour WebM file to MP4 take?
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Depends on the codec change. Same-codec re-mux: 30-60 seconds (no re-encode). Re-encode to a different codec: typically 0.3-0.7x source duration on our GPU pipeline, so a 1-hour WebM -> MP4 finishes in 18-40 minutes; AV1 re-encodes are 2-3x slower.
What is the max resolution supported for WebM to MP4?
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Up to 8K (7680x4320) on Pro. Free is capped at 4K per the file-size limit. HDR metadata (HDR10, Dolby Vision) is preserved where both WebM and MP4 containers and codecs support it; SDR sources stay SDR.
Is my WebM video private during MP4 conversion?
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Yes — uploaded video files are processed in isolated workers and deleted within minutes of completion. No human review, no retention beyond the documented window. See /privacy/.
Can I crop or trim during the WebM to MP4 step?
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Not in the same step — use /video-trim/ or /video-cutter/ to clip the WebM first, then queue the WebM -> MP4 conversion. Trim-then-convert is faster than re-encoding the whole file just to crop the output.
Why is the MP4 file blurry compared to the WebM source?
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Almost always a bitrate-too-low setting. Re-encoding a high-bitrate WebM into a lower-bitrate MP4 at the default CRF compresses motion-heavy scenes heavily. Push CRF down to 16-18 (or set an explicit bitrate ceiling) and re-run to recover quality.
Does the WebM to MP4 converter support subtitles?
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Yes — embedded subtitle tracks (mov_text in MP4, SRT / ASS in MKV, WebVTT in WebM) are preserved when both WebM and MP4 containers support them. Burned-in (hardsub) subtitles transfer automatically because they are part of the pixel data.