MyMediaTools

Convert M4V to 3GPP — Free Online Tool

Convert M4V files (Apple's iTunes-compatible MPEG-4 container) to 3GPP format, re-encoding video with H.264 and audio with AAC at mobile-optimized bitrates. This conversion is ideal for making iTunes video content compatible with older mobile devices and 3G networks that require the lightweight 3GP container.

FFmpeg Command

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Estimated output:

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How It Works

M4V and 3GP both support H.264 video and AAC audio, but they are not a simple remux — the output must conform to 3GPP's stricter constraints on bitrate, resolution, and container structure. The video stream is re-encoded using libx264 at CRF 23, which balances quality against the low-bandwidth requirements of 3G mobile playback. The audio is re-encoded to AAC at 64k, a significantly lower bitrate than typical M4V audio, reflecting 3GP's mobile-first design philosophy. The -movflags +faststart flag reorganizes metadata to the front of the file, enabling progressive streaming playback on mobile networks before the full file is downloaded. Any chapters, multiple audio tracks, or subtitle streams present in the M4V source are dropped, as the 3GP format does not support those features.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary. In this browser tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm), so no file data is sent to a server.
-i input.m4v Specifies the input file in M4V format. FFmpeg reads the Apple MPEG-4 container and demuxes its video, audio, and any metadata streams for processing.
-c:v libx264 Re-encodes the video stream using the libx264 H.264 encoder, which is required to produce a 3GP-compatible video stream. Even though M4V often already contains H.264, a full re-encode ensures the output stream conforms to 3GP container constraints.
-c:a aac Encodes the audio stream as AAC, the standard audio codec for 3GP files. M4V typically carries AAC audio already, but re-encoding at the lower 64k bitrate is necessary to meet 3GP's mobile-optimized audio profile.
-crf 23 Sets the Constant Rate Factor for the H.264 video encode to 23, the 3GP default quality level. This balances visual fidelity against file size for mobile playback — lower values produce better quality at larger file sizes.
-b:a 64k Sets the AAC audio bitrate to 64 kilobits per second, which is 3GP's standard default and reflects the format's design for low-bandwidth 3G network delivery. This is noticeably lower than the 128k+ audio typically found in M4V source files.
-movflags +faststart Moves the 3GP container's metadata (moov atom) to the beginning of the file after encoding completes. This allows mobile devices and streaming players to begin playback before the entire file is downloaded, which is critical for 3G network delivery.
output.3gp Specifies the output filename with the .3gp extension. FFmpeg uses this extension to select the 3GPP container format for muxing the re-encoded H.264 video and AAC audio streams.

Common Use Cases

  • Making iTunes movie or TV show downloads (DRM-free M4V exports) playable on legacy 3G-era smartphones that only support the 3GP container
  • Reducing file size of M4V video content for sharing over SMS or MMS on mobile networks with strict attachment size limits
  • Preparing video content for playback on older feature phones and embedded mobile devices that have hardware decoders limited to 3GP
  • Archiving or distributing short-form M4V clips (trailers, previews) in a format compatible with early 2000s mobile video players
  • Transcoding M4V recordings from screen capture or FaceTime exports into a lightweight 3GP format for low-bandwidth upload to mobile video platforms

Frequently Asked Questions

No. M4V files purchased from the iTunes Store and protected by Apple's FairPlay DRM cannot be decoded or converted by FFmpeg or any browser-based tool. Only DRM-free M4V files — such as those from ripped Blu-rays, recordings made with QuickTime, or iTunes purchases that were later stripped of DRM through authorized means — can be processed. If your M4V file plays outside of Apple's ecosystem without authentication, it is likely DRM-free and will convert successfully.
The conversion drops the audio bitrate to 64k AAC, compared to the 128k–256k AAC bitrate typical in M4V files from iTunes. This is intentional: 3GP was designed for 3G mobile networks where bandwidth is severely limited, and 64k is the format's standard default. The result is audibly thinner audio, particularly on music or dialogue with wide dynamic range. If quality matters more than compatibility, you can increase the -b:a value in the FFmpeg command to 96k or 128k, though not all 3GP-capable players will handle higher audio bitrates reliably.
No. The 3GP container format does not support chapters, subtitle streams, or multiple audio tracks, all of which are features that M4V files may carry. FFmpeg will silently discard these streams during the conversion. If your M4V contains burned-in subtitles (rendered directly into the video frames), those will survive because they are part of the video picture itself, not a separate stream.
The 3GP output will typically be substantially smaller than the M4V source. The reduction comes from the lower audio bitrate (64k vs. 128k+), the 3GPP container's mobile-optimized overhead, and the CRF 23 re-encoding which targets a similar visual quality level but strips the M4V's more complex stream metadata. For a typical 500MB M4V TV episode, the 3GP output might range from 100MB to 250MB depending on resolution and motion complexity in the source.
Adjust the -crf value in the command. The 3GP output supports CRF values between 18 and 28 — lower numbers produce higher quality at larger file sizes, and higher numbers produce smaller files with more visible compression artifacts. For example, replacing -crf 23 with -crf 18 gives near-transparent quality suitable for archiving, while -crf 28 aggressively reduces file size for bandwidth-constrained delivery. Avoid going below CRF 18 or above CRF 28 for 3GP output, as extreme values either waste space or produce visually unacceptable results for mobile screens.
Yes. On Linux or macOS, you can wrap the command in a shell loop: for f in *.m4v; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -movflags +faststart "${f%.m4v}.3gp"; done. On Windows Command Prompt, use: for %f in (*.m4v) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -movflags +faststart "%~nf.3gp". The browser-based tool processes one file at a time, so the FFmpeg command is particularly valuable when you have a batch of M4V files to convert.

Technical Notes

M4V is structurally nearly identical to MP4, and both containers can carry H.264 video and AAC audio, which means the codec choice is compatible. However, 3GP imposes tighter constraints: it was standardized for 3GPP Release 4 devices and assumes low-resolution displays (typically 176×144 or 320×240), modest CPU decoding capabilities, and constrained network throughput. FFmpeg does not automatically downscale the resolution during this conversion — if your M4V source is 1080p or 4K, the 3GP output will retain that resolution, which may cause playback failures on actual legacy 3G devices. For strict device compatibility, you should add -vf scale=320:-2 to cap the width at 320 pixels. The MJPEG video codec is also an option within 3GP (for motion-JPEG encoding), but libx264 is strongly preferred for compression efficiency. Note that 3GP's lack of subtitle and chapter support means any rich metadata from the M4V — including iTunes metadata tags like show name, episode number, and artwork — will be lost or truncated in the output container.

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