Step 1: Share your FLV files using the button above or by drag and drop.
Step 2: Click the 'Transform' button to start the transformation.
Step 3: Grab your converted M4V files.
FLV to M4V Transformation FAQ
How do I re-encode FLV to M4V without losing video quality?
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Upload your FLV file and set Quality to High Quality in the conversion options. That re-encodes the video at the highest quality setting (CRF 18 for H.264 and VP9 output), which keeps the most detail at the cost of a larger file. The default, Balanced, uses the standard setting. The M4V output gets a codec its container supports: H.264 for MP4, MOV and MKV, VP9 for WebM. FLV typically holds Sorenson Spark or H.264 video with MP3 or AAC audio, wrapped in a stream format designed for RTMP delivery. Structurally an M4V is an MP4 — H.264 or HEVC with AAC — with optional Apple FairPlay DRM and iTunes chapter metadata.
Can I add selectable subtitles once the file is M4V?
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Yes. FLV has no usable soft-subtitle track, so subtitles for FLV content had to be burned into the picture or shipped as a separate sidecar file. M4V carries subtitles as their own selectable stream, so after conversion you can attach an SRT track the viewer can switch on, switch off or restyle.
Can the M4V hold more than one audio track?
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Yes, and it is a real upgrade over FLV. M4V treats every audio stream as a first-class track, so an original-language mix, a dub and a director commentary can live in one file with the player switching between them on demand. M4V keeps chapter markers, artwork and subtitle tracks in the shape the Apple TV app expects, which plain MP4 often loses.
Does M4V support chapter markers that FLV did not?
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It does. M4V stores chapters as container metadata, so a long recording can be navigated by section instead of by scrubbing a progress bar. FLV has nowhere to put that information, so the converted M4V starts with no chapters; add markers afterwards with a tool such as MKVToolNix or ffmpeg.
Is it worth converting old FLV recordings to M4V at all?
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For anything you intend to keep, yes. FLV belongs to an earlier generation of video tooling and the software that reads it is steadily disappearing from phones, browsers and operating systems. Moving the footage to M4V now, while a clean decoder still exists, is the difference between an archive you can open in ten years and one you cannot. No current browser, phone or TV can play FLV — anything still in this container has to be moved out of it to remain watchable.
Which video codec does the M4V output use?
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It depends on the M4V container. MP4, MOV and MKV output use H.264, which plays on practically every phone, browser and TV. WebM output uses VP9. AVI, WMV and MPEG output use the older codecs those formats were designed for. M4V is Apple’s variant of MP4, used by iTunes and the Apple TV app for films and TV episodes.
Will my audio track survive FLV to M4V conversion?
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Yes, the main audio track comes through, re-encoded to a codec the M4V container plays, for example AAC in MP4 and MOV or Opus in WebM. Most conversions keep only that one track (the one with the most channels), so alternate languages and commentary are dropped. MP4 to MOV, and AVI, WMV, MPEG, FLV, VOB or M4V to MKV, keep every audio track.
Can I keep the original framerate when converting FLV to M4V?
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Yes. The frame rate is kept unless you change it: a 24 fps FLV stays 24 fps in the M4V. The Frame Rate setting can also convert to 60, 30 or 24 fps. It changes the rate only; it does not deinterlace the video or remove 3:2 pulldown.
How much will the file size change going from FLV to M4V?
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It depends on what happens to the video. MKV to MP4 or MOV with the default settings copies the video stream unchanged, so the size stays close to the source. Most other pairs re-encode it: a high-bitrate FLV usually comes out smaller, while an already heavily compressed one can grow. Smaller File under Quality gives the smallest output, and H.265 in the Codec setting (MP4, MOV and MKV) is usually smaller than H.264 at similar quality but plays on fewer devices.
Will the M4V file play on iPhone, Android, and Smart TVs?
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MP4 with H.264 plays on practically every phone, browser and TV. MOV with H.264 plays on Apple devices and most TVs but not on every older Android phone. MKV needs an app such as VLC on iOS, and WebM is at home in browsers. There is no device preset on this page, so choose the target format your device supports. DRM-protected M4V purchases cannot be converted by anything; only unprotected M4V files are convertible, and non-Apple players often need the extension renamed.
How long does converting a 1-hour FLV video to M4V take?
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There is no fixed time: it depends on the length, the resolution and the target format. Conversions run on our servers' CPUs with software encoders; there is no GPU acceleration. MKV to MP4 or MOV with the default settings copies the video stream and is the quickest. A re-encode to H.264 takes longer, and WebM (VP9) is the slowest target, several times slower than H.264 in our tests.
What is the maximum resolution supported for FLV to M4V?
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The converter has no resolution cap of its own; the limit is the upload size allowed on your plan, and the resolution stays as it is unless you choose 1080p, 720p or 480p. There is no HDR processing or tone mapping. When the video stream is copied (MKV to MP4 or MOV with the default settings), HDR10 passes through untouched. A re-encode drops the HDR10 mastering metadata, and with a Quality, Resolution or Frame Rate setting some pairs also reduce the video to 8-bit colour, so an HDR FLV can look washed out.
