Convert M2TS to M4V — Free Online Tool
Convert M2TS Blu-ray and AVCHD video files to M4V for seamless playback on Apple devices, iTunes, and iOS. This tool re-encodes the video using H.264 and wraps it in Apple's MPEG-4 container with faststart optimization, making your high-definition disc content immediately compatible with the Apple ecosystem.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
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
M2TS files use an MPEG-2 Transport Stream container commonly carrying H.264 or MPEG-2 video alongside multi-channel audio codecs like Dolby TrueHD, DTS-HD MA, or AC-3 — none of which are natively supported in the M4V container. During conversion, the video stream is re-encoded to H.264 (libx264) at CRF 23, which targets visually transparent quality while reducing file size from the often uncompressed or losslessly-compressed Blu-ray source. The audio is transcoded to AAC at 128k, since M4V does not support the lossless or object-based audio formats common on Blu-ray. The output M4V is written with the -movflags +faststart flag, which relocates the MP4 index (moov atom) to the beginning of the file so it can begin playing before fully downloading — essential for iTunes and streaming use.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that handles all decoding, encoding, and muxing operations in this conversion from M2TS to M4V. |
-i input.m2ts
|
Specifies the input file — an M2TS container, typically sourced from a Blu-ray disc rip or AVCHD camcorder, which may contain MPEG-2 or H.264 video alongside lossless or surround audio tracks. |
-c:v libx264
|
Re-encodes the video stream using the H.264 codec (libx264), which is required for M4V compatibility with iTunes, iOS, and Apple TV — regardless of whether the source M2TS carried H.264 or MPEG-2 video. |
-c:a aac
|
Transcodes the audio stream to AAC, replacing any Dolby TrueHD, DTS-HD, AC-3, or LPCM audio present in the M2TS source with a format natively supported by all Apple devices and the M4V container. |
-crf 23
|
Sets the Constant Rate Factor for libx264 to 23, the default quality level that balances file size and visual fidelity for most high-definition content from Blu-ray or AVCHD sources; lower values like 18 produce higher quality at larger file sizes. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, which is suitable for stereo audio; since Blu-ray M2TS files often contain multi-channel surround tracks that get downmixed, you may want to increase this to 192k or 256k to preserve more audio detail. |
-movflags +faststart
|
Moves the MP4 moov atom (the file's index and metadata) to the beginning of the output M4V file after encoding, enabling iTunes import compatibility and allowing the file to begin playing in a browser or streaming context before it has fully downloaded. |
output.m4v
|
Defines the output file with the .m4v extension, signaling to FFmpeg to mux the encoded H.264 and AAC streams into Apple's MPEG-4 container format, which is recognized natively by iTunes, QuickTime, and all iOS devices. |
Common Use Cases
- Adding Blu-ray disc rips or AVCHD camcorder footage to your iTunes library for playback on Apple TV, iPhone, or iPad
- Converting M2TS recordings from a Sony or Panasonic AVCHD camcorder into a format that iMovie or Final Cut Pro can import without plugins
- Preparing high-definition M2TS content for streaming within an Apple ecosystem home server such as Plex with an Apple TV client
- Archiving M2TS broadcast recordings from a Blu-ray recorder into a smaller, widely-compatible M4V file for long-term storage
- Stripping incompatible Dolby TrueHD or DTS audio from a Blu-ray rip and re-encoding to AAC so the file plays on iOS devices without error
- Creating an iTunes-compatible version of a home movie shot in AVCHD to share with family through the Apple ecosystem
Frequently Asked Questions
Yes, some quality loss occurs because M2TS sources — especially from Blu-ray — often carry near-lossless or very high-bitrate video that must be re-encoded to H.264 for M4V compatibility. The default CRF 23 setting targets visually near-transparent quality for most content, meaning the difference is difficult to see at normal viewing distances. However, if your M2TS already contains H.264 video (common in AVCHD), you are re-encoding H.264 to H.264, which introduces a generation loss; lowering the CRF value to 18 or below will preserve more detail at the cost of a larger file.
M4V does not support Dolby TrueHD, DTS-HD MA, or standard DTS audio — these are transcoded to AAC during conversion. The default 128k AAC bitrate is adequate for stereo audio, but if your source has a 5.1 or 7.1 surround track, FFmpeg will downmix it to stereo unless you specify channel mapping options. For better surround fidelity, consider increasing the audio bitrate to 256k or 320k using the -b:a flag in the command.
Yes — M4V with H.264 video and AAC audio is the native format for iTunes purchases and is fully compatible with iPhone, iPad, Apple TV, and iTunes on Mac and Windows. The -movflags +faststart flag used in this conversion also ensures the file streams progressively, which is a requirement for some iTunes import workflows. If the file is extremely large or exceeds Apple's resolution limits for a given device, iTunes may still refuse to sync it, but playback in the Files app or VLC on iOS will work regardless.
M2TS files can carry PGS (Blu-ray bitmap) subtitle tracks, but M4V only supports text-based subtitle formats such as MOV text or TTXT. PGS subtitles cannot be directly remuxed into M4V, so by default they are dropped during this conversion. If you need subtitles in the output, you would need to either burn them into the video using a filter (-vf subtitles) or convert them to a supported text format separately before muxing.
The -crf flag controls video quality — lower values mean higher quality and larger files, while higher values mean lower quality and smaller files. The scale runs from 0 (lossless) to 51 (worst quality), with 23 as the default. To get a noticeably higher-quality output from a Blu-ray source, try -crf 18; for a smaller file more suitable for mobile storage, try -crf 28. For example: ffmpeg -i input.m2ts -c:v libx264 -c:a aac -crf 18 -b:a 192k -movflags +faststart output.m4v.
Yes — on Linux or macOS you can use a shell loop: for f in *.m2ts; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.m2ts}.m4v"; done. On Windows Command Prompt, use: for %f in (*.m2ts) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.m4v". Note that M2TS files from Blu-ray are often several gigabytes each, so batch processing can take significant time and this browser-based tool is best suited for single files under 1GB.
Technical Notes
M2TS is a transport stream format designed for broadcast and disc delivery, which means it carries additional overhead — program tables, null packets, and timing information — that is stripped away during muxing into M4V's MPEG-4 container. The video re-encoding from whatever codec the M2TS carries (often AVC/H.264 in AVCHD, or MPEG-2 in older Blu-ray titles) to libx264 is the most computationally expensive part of this conversion and can take considerably longer than a simple remux. M4V is structurally identical to MP4 but uses the .m4v extension as an Apple convention; most non-Apple players handle it identically to .mp4. The -movflags +faststart post-processes the output file to move the moov atom to the front, which is critical for iTunes compatibility and HTTP progressive streaming but does require a second pass over the file after encoding completes. Chapter markers present in Blu-ray M2TS sources are generally not carried through this conversion because M2TS chapter data is stored in separate BDMV index files rather than in the stream itself, though M4V does support chapters if you add them via a separate tool. Multiple audio tracks from the M2TS source are not automatically preserved in this default command; only the first detected audio track is encoded.