MPEG4 to GSM Converter
Processing entirely on your device — large files may take a moment.
MPEG-4 Video and GSM 06.10 Speech exist for different jobs: MPEG4 is a common shorthand extension for MPEG-4 Part 2 streams — handled through the same MPEG program-stream path. Convert GSM speech recordings to WAV or MP3.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How MPEG4 compares to GSM
| MPEG4 | GSM | |
|---|---|---|
| Compatibility | Universal decode | Asterisk, SoX, ffmpeg |
| Best for | Legacy disc and capture video | Telephony recordings |
How to convert MPEG4 to GSM
- 1
Select your files
Select your MPEG4 video.
- 2
Convert instantly
The engine demuxes the container and encodes the audio track into your chosen format.
- 3
Download results
Download the GSM audio — the video track is simply dropped.
About the MPEG4 format
MPG (MPEG program stream) usually means MPEG-1 or MPEG-2 video — the codecs of VCD, SVCD and DVD, and of countless home video captures in the 1990s and 2000s. MPEG-1 tops out around VHS-grade 352×288; MPEG-2 delivers proper standard definition and still runs inside broadcast and DVD infrastructure.
Playback compatibility is its superpower: MPEG-1/2 decode paths exist in every player and hardware made this century. Quality-to-bitrate efficiency, however, is a generation behind H.264 — converting old MPG files to MP4 typically halves their size.
+Strengths
- ✓Decodes on essentially every player and device
- ✓Simple, battle-tested standard
!Limitations
- −Inefficient codecs by modern standards
- −MPEG-1 is VHS-grade at best
About the GSM format
GSM 06.10 is the speech codec of the original GSM mobile network — 13 kbit/s RPE-LTP that made digital cellphone calls possible in 1991 and still lives inside VoIP systems, old answering machines and Asterisk PBX recordings.
It is lossy speech, not music: converting GSM to WAV or MP3 preserves intelligibility perfectly while finally letting desktop players open the file without special codecs.
+Strengths
- ✓Tiny bitrate for speech intelligibility
- ✓Ubiquitous in telephony systems
- ✓Decodes natively via ffmpeg
!Limitations
- −Speech-only quality — music falls apart
- −13 kbit/s artifacts are audible
- −8000 Hz sample rate only
Why convert MPEG4 to GSM?
Think of it as moving your file to the container that fits the job. Inefficient codecs by modern standards GSM works differently: Tiny bitrate for speech intelligibility If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this MPEG4 to GSM converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for MPEG4 to GSM?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Why is video conversion slower than image conversion?
Every frame has to be decoded and re-encoded. This site runs that work on your own CPU via WebAssembly — nothing is uploaded, but a multi-minute video reasonably takes a few minutes. Images, by comparison, are single-frame jobs.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of GSM, staying in sync with the video. If your MPEG4 file has multiple audio tracks, the first one is used.