Step 1: Send your M4V files using the button above or by move and place.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Export your converted MP4 files.
M4V to MP4 Conversion FAQ
How do I re-encode M4V to MP4 without quality loss?
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Upload your M4V 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 and WebM default to H.265 and VP9 respectively for better compression at the same quality. You can override codec choice in the advanced options before conversion.
Will my audio track survive M4V to MP4 conversion?
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Yes — audio is re-muxed (when M4V 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.
Can I keep the original framerate when converting M4V to MP4?
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By default, framerate is unchanged (M4V 24fps stays 24fps in MP4). If you need to change it (e.g. interlaced 29.97 → progressive 30fps), use the framerate option, which handles 3:2 pulldown and deinterlacing in the same pass.
What is the file size difference between M4V and MP4?
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Same-codec re-muxes (e.g. M4V → MP4 where both use H.264) produce nearly-identical sizes. Codec changes can swing the size dramatically: H.264 → H.265 typically halves the file at the same visual quality; H.264 → VP9 is roughly comparable.
Will the MP4 file play on iPhone / Android / Smart TV?
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MP4 / H.264 plays natively everywhere. MOV / H.264 plays on Apple devices and most Smart TVs but not on older Android. MKV needs VLC on iOS. The advanced options include a "device compatibility" preset that picks the safest codec / container combination for the target device.
How long does converting a 1-hour M4V file to MP4 take?
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It 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 file finishes in 18-40 minutes.
What is the max resolution supported for M4V to MP4?
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Up to 8K (7680×4320) on Premium. Free users are capped at 4K (3840×2160) per the file-size limit. HDR metadata (HDR10, Dolby Vision) is preserved where both M4V and MP4 containers support it.
Is my M4V video private during conversion?
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Yes — uploaded video files are processed in isolated workers and deleted within minutes of completion. We never view, store, retain, or share content. See /privacy/ for the full data retention window.
Can I crop or trim during the M4V to MP4 conversion?
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Not in the same step — use /video-trim/ or /video-cutter/ to trim before converting, then queue the M4V → MP4 step. Trimming and converting in series is faster than re-encoding the whole file just to crop.
Why is the MP4 file blurry / pixelated compared to the M4V source?
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Almost always a bitrate-too-low setting. Re-encoding from a high-bitrate M4V into a lower-bitrate MP4 at the default CRF compresses heavily on motion-heavy scenes. Push CRF down to 16-18 (or set explicit bitrate) and re-run to recover quality.
Does the M4V to MP4 converter support subtitles?
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Yes — embedded subtitle tracks (mov_text in MP4, SRT/ASS in MKV) are preserved when both M4V and MP4 containers support them. Burned-in (hardsub) subtitles transfer automatically because they are part of the video frame.