Step 1: Transfer your M4V files using the button above or by slide and deposit.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Retrieve your converted FLV files.
M4V to FLV Conversion FAQ
How do I re-encode M4V to FLV without losing video quality?
+
Upload your M4V file and the converter runs a CRF-based re-encode targeting visually-lossless FLV output (CRF 18 by default, lower values = larger file / higher quality). The codec is chosen to match the FLV container — H.264 for broad-compat MP4, H.265 for size-efficient MKV, VP9 for WebM, AV1 for newer pipelines. Structurally an M4V is an MP4 — H.264 or HEVC with AAC — with optional Apple FairPlay DRM and iTunes chapter metadata. FLV typically holds Sorenson Spark or H.264 video with MP3 or AAC audio, wrapped in a stream format designed for RTMP delivery.
What happens to the subtitle tracks in my M4V file?
+
They cannot stay selectable, because FLV has no soft-subtitle stream to hold them. There are two ways out: burn them into the video during conversion, which makes them permanent and unstyleable, or export them as a separate .srt alongside the FLV for the player to load. The converter tells you which it did rather than dropping them silently. No current browser, phone or TV can play FLV — anything still in this container has to be moved out of it to remain watchable.
My M4V has several audio tracks — do they all survive into the FLV?
+
Not dependably. M4V stores multiple audio streams as first-class tracks, but FLV playback support past the first track is inconsistent, so most players will only ever expose one. Choose the track you actually want before converting; the others are better extracted to their own files than left in a container that hides them. M4V keeps chapter markers, artwork and subtitle tracks in the shape the Apple TV app expects, which plain MP4 often loses.
Why does my M4V file fail to convert to FLV?
+
Almost always DRM. Some M4V files are encrypted at the bitstream level by the store or software that issued them, and an encrypted stream cannot be decoded by us or by anything else without the licence key. Files you recorded, exported or downloaded unprotected convert normally; a licensed purchase will not, and no converter can honestly promise otherwise. DRM-protected M4V purchases cannot be converted by anything; only unprotected M4V files are convertible, and non-Apple players often need the extension renamed.
Will the FLV still play smoothly on a phone or a TV?
+
It may not. M4V is decoded by dedicated silicon on phones, tablets and TVs, which is why it plays without flattening the battery. FLV typically falls back to software decoding on the same hardware — higher CPU load, a warmer device, and dropped frames on 4K material. For a device target, M4V is the safer container to stay in.
What happens to 5.1 surround audio when converting M4V to FLV?
+
It is downmixed to stereo, because FLV has no dependable multichannel path. The fold-down uses the standard ITU coefficients so dialogue in the centre channel stays intelligible and the surrounds come in at reduced level rather than vanishing. Anything that relied on discrete channel placement is gone after that.
Why would I convert M4V to an older format like FLV?
+
Because a lot of hardware never learned anything newer and never will. DVD players, in-car head units, camcorder playback modes, industrial displays and plenty of broadcast ingest equipment accept FLV and nothing else. The conversion is a deliberate step down in efficiency, bought in exchange for working on a device that has no other option. FLV’s low per-packet overhead made it excellent at streaming over the unreliable connections of its era, and huge archives of it still exist.
Which video codec does the FLV output use?
+
It depends on the FLV container. MP4 defaults to H.264 for the broadest playback support across phones, browsers, and Smart TVs. MKV defaults to H.265 / HEVC for roughly half the file size at equivalent quality. WebM defaults to VP9. The advanced options expose explicit codec choice if you need to override. FLV is the Flash Video container that carried essentially all web video from roughly 2003 until Flash was switched off at the end of 2020.
Will my audio track survive M4V to FLV conversion?
+
Yes. When M4V and FLV share an audio codec (e.g. both carry AAC), audio is re-muxed with no re-encode — bit-identical. When the codecs differ, audio is transcoded to AAC / Opus / Vorbis depending on what the FLV container supports. Multi-track audio (commentary, alternate languages) is preserved.
Can I keep the original framerate when converting M4V to FLV?
+
By default yes — a 24fps M4V stays 24fps in FLV; a 60fps M4V stays 60fps. If you need to change rate (e.g. interlaced 29.97 → progressive 30, or 60 → 30 for upload limits), the framerate option handles 3:2 pulldown, deinterlacing, and frame-blending in the same encode pass.
How much will the file size change going from M4V to FLV?
+
Same-codec re-mux (M4V H.264 → FLV H.264 just changing container): nearly identical size. Codec change can swing dramatically: H.264 → H.265 typically halves the file at the same visual quality; VP9 is roughly comparable; AV1 cuts another 20-30% but is slower to encode.
Will the FLV file play on iPhone, Android, and Smart TVs?
+
MP4 / H.264 plays natively on every modern device. MOV / H.264 plays on Apple devices and most TVs but not always on older Android. MKV needs VLC on iOS. WebM is browser-first. The advanced options include a "device compatibility" preset that picks the safest FLV codec / container for your target.
FLV (Flash Video) is a video container format developed by Adobe. It is commonly used for online video streaming and is supported by Adobe Flash Player.
