Convert MPG to M4B — Free Online Tool
Convert MPG video files to M4B audiobook format by extracting and re-encoding the audio track to AAC, producing a bookmarkable, chapter-capable file ideal for audiobooks and podcasts. This tool strips the MPEG-1/2 video stream entirely and outputs a compact M4B container optimized for Apple Books, iTunes, and podcast players.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your MPG file here
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Free — no uploads, no signups. Your files never leave your browser.
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
MPG files carry video encoded in MPEG-1 or MPEG-2, with audio typically stored as MP2 (MPEG Layer II). M4B is a purely audio container — it has no video track — so the conversion process discards the video stream entirely and focuses on the audio. The MP2 audio from the MPG is decoded and re-encoded into AAC (Advanced Audio Coding), which is the native codec for M4B and delivers better quality at lower bitrates than MP2. The resulting audio is wrapped in an MPEG-4 container with the +faststart flag applied, which repositions the file's metadata header to the beginning of the file for efficient streaming and quick playback start. If the original MPG was a recorded lecture, narration, or spoken-word broadcast, the resulting M4B will support bookmarking and chapter navigation in compatible players.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg media processing engine. In this browser-based tool, FFmpeg runs entirely via WebAssembly (FFmpeg.wasm) with no server involvement — your MPG file never leaves your device. |
-i input.mpg
|
Specifies the input file, an MPG container holding an MPEG-1 or MPEG-2 video stream and typically an MP2 audio stream. FFmpeg will demux both streams, but only the audio will be used in this conversion. |
-c:a aac
|
Sets the audio codec to AAC (Advanced Audio Coding), which is the native and required audio codec for M4B files. The MP2 audio from the MPG source is decoded and re-encoded as AAC, delivering better compression efficiency and broader compatibility with audiobook and podcast players. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, the default for M4B output. This is well-suited for spoken-word content such as audiobooks and lectures extracted from MPG recordings, balancing file size and intelligibility. Raise this to 192k or 256k for music-heavy source material. |
-movflags +faststart
|
Moves the MPEG-4 container's metadata (the moov atom) to the beginning of the output file. This is essential for M4B files used as audiobooks or podcasts, as it allows players like Apple Books and podcast apps to begin streaming or playback immediately without waiting for the entire file to load. |
output.m4b
|
Defines the output filename and tells FFmpeg to write an MPEG-4 audio container with the .m4b extension. The M4B extension signals to Apple Books, iTunes, and compatible podcast players that this file supports bookmarking and chapter navigation. |
Common Use Cases
- Converting a recorded TV documentary or educational broadcast saved as MPG into a portable M4B audiobook to listen to during commutes without needing to watch the video
- Extracting narration or commentary from a DVD-ripped MPG lecture series and repackaging it as an M4B for use in Apple Books or Overcast
- Turning a VCD-sourced MPG of a recorded spoken-word performance or reading into a bookmarkable M4B that remembers your playback position
- Repurposing old MPEG-2 broadcast recordings of radio programs or news segments into M4B podcast episodes for personal archiving
- Extracting the audio track from an MPG-format training video to create a standalone M4B study guide listenable on an iPhone without the video
- Converting a digitized VHS recording of a speech or sermon stored as MPG into an M4B file for distribution through a podcast feed
Frequently Asked Questions
No — M4B is a strictly audio-only format and cannot contain a video stream. During this conversion, the MPEG-1 or MPEG-2 video track from your MPG is completely discarded. Only the audio track is decoded and re-encoded as AAC audio inside the M4B container. If preserving the video is important, you should convert to a format like MP4 instead.
MPG files typically store audio as MP2 (MPEG Layer II), an older lossy codec used in broadcast and DVD applications. During conversion, that MP2 audio is decoded to raw PCM and then re-encoded as AAC at 128k bitrate. This is a lossy-to-lossy transcode, meaning a small amount of additional quality degradation occurs due to the re-encoding step. For spoken-word content like audiobooks or lectures, AAC at 128k is generally transparent and the difference is rarely noticeable, but music-heavy content may show minor artifacts.
The M4B container format fully supports chapters and bookmarking, and Apple Books, iTunes, and many podcast apps will remember your playback position. However, this conversion tool extracts audio from a single MPG file without injecting chapter metadata, so the output will be one continuous audio track. To add chapters, you would need to use additional FFmpeg metadata tagging or a dedicated audiobook authoring tool after conversion.
M4B files are typically much smaller than the source MPG because the entire video stream is removed and only AAC audio at 128k bitrate is retained. An MPG file at several hundred megabytes may produce an M4B of just a few megabytes for the same duration of audio. The exact size depends on the length of the audio — at 128k AAC, you can expect roughly 1 MB per minute of audio.
The default command uses '-b:a 128k', which sets the AAC audio bitrate to 128 kilobits per second. For higher fidelity — especially useful if the MPG source contains music or high-quality narration — you can change this value to '-b:a 192k' or '-b:a 256k'. The command would then read: ffmpeg -i input.mpg -c:a aac -b:a 256k -movflags +faststart output.m4b. Higher bitrates increase file size proportionally but improve audio clarity.
The displayed command processes one file at a time, but you can run it in a loop from a terminal. On Linux or macOS, use: for f in *.mpg; do ffmpeg -i "$f" -c:a aac -b:a 128k -movflags +faststart "${f%.mpg}.m4b"; done. On Windows PowerShell: Get-ChildItem *.mpg | ForEach-Object { ffmpeg -i $_.FullName -c:a aac -b:a 128k -movflags +faststart ($_.BaseName + '.m4b') }. This is particularly useful for converting a series of lecture or episode files in one pass.
Technical Notes
MPG is a lossy container rooted in the MPEG-1 and MPEG-2 standards, historically used for VCD, DVD, and broadcast television. Its audio stream is almost universally MP2 — an older lossy format that predates MP3 and AAC. M4B is an MPEG-4 audio container, technically a variant of M4A, distinguished by its support for chapter markers and bookmarking. The conversion from MPG to M4B is a transcode: MP2 audio is fully decoded and re-encoded as AAC, introducing a second generation of lossy compression. For spoken-word content at 128k AAC, this quality loss is negligible. No subtitle or metadata streams from the MPG are preserved, as M4B in this conversion does not carry subtitle data, and MPG typically carries minimal embedded metadata. The -movflags +faststart flag reorganizes the MPEG-4 container's moov atom to the front of the file, which is a best practice for streaming and ensures podcast clients and audiobook apps can begin playback before the entire file has downloaded. Files processed in the browser via FFmpeg.wasm are limited to 1GB; for larger archival MPG files, the displayed FFmpeg command can be run locally on any desktop with FFmpeg installed.