Convert TS to M4B — Free Online Tool
Convert TS broadcast stream files to M4B audiobook format, extracting the AAC audio track and packaging it with chapter and bookmarking support. Ideal for turning recorded radio programs, podcasts captured as transport streams, or broadcast audio into a portable audiobook file you can resume anywhere.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
A TS (MPEG-2 Transport Stream) file is a broadcast container designed to carry multiplexed audio, video, and data streams — often containing an AAC or AC-3 audio track alongside H.264 video. M4B is an audio-only MPEG-4 container used exclusively for audiobooks and podcasts, so the video stream is discarded entirely during this conversion. If the TS file's audio is already AAC, the conversion is essentially a remux of the audio stream into the new container with minimal quality loss. If the source audio uses a different codec (such as AC-3 or MP3), it is transcoded to AAC at the specified bitrate. The output file gains M4B-specific metadata support including chapters and playback position bookmarking, which the original TS format does not offer.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, the open-source multimedia processing engine that handles the TS-to-M4B stream demuxing, optional audio transcoding, and container remuxing entirely within your browser via WebAssembly. |
-i input.ts
|
Specifies the input MPEG-2 Transport Stream file. FFmpeg parses the TS container to identify all multiplexed streams — video, audio, and any subtitles or data — before deciding what to extract and convert. |
-c:a aac
|
Sets the audio codec to AAC (Advanced Audio Coding), the only audio codec natively supported by the M4B container for audiobook playback compatibility. AAC provides efficient compression suitable for speech and music in audiobook files. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, a standard quality level that balances file size and audio fidelity for spoken-word content typical of radio broadcasts and audiobooks converted from TS sources. |
-movflags +faststart
|
Relocates the M4B file's metadata atom (the 'moov' box) to the start of the file, enabling audiobook players and podcast apps to begin playback and display chapter information before the full file has been transferred or buffered. |
output.m4b
|
Specifies the output filename with the .m4b extension, which signals to Apple devices, Overcast, Pocket Casts, and other compatible players that this file is an audiobook or podcast with bookmarking and chapter navigation support. |
Common Use Cases
- Converting a recorded over-the-air radio broadcast (captured as a TS file by a DVR) into an M4B audiobook you can listen to and resume on your iPhone or Apple Books
- Packaging a recorded lecture or conference talk captured from a broadcast stream into M4B format so students can bookmark their position and resume later
- Stripping the audio from a recorded TV documentary stored as a TS file to create a narration-only M4B for listening during a commute
- Converting podcast episodes that were archived in TS format by a broadcast recorder into proper M4B files compatible with podcast apps that support bookmarking
- Extracting the audio commentary track from a sports broadcast TS recording into an M4B file for later reference, discarding the video to save storage space
- Preparing serialized spoken-word content recorded from digital television into chapter-enabled M4B files for distribution as an audiobook series
Frequently Asked Questions
It depends on the audio codec in your source TS file. If the TS already contains an AAC audio track, the stream can be remuxed into the M4B container with virtually no quality loss — but this tool transcodes to AAC at 128k by default, so some re-encoding occurs regardless. If the source audio is AC-3 (Dolby Digital), which is common in North American broadcast TS files, transcoding to AAC at 128k will introduce some generational quality loss. For the best quality, raise the audio bitrate to 192k or 256k when dealing with AC-3 source audio.
No. M4B is an audio-only single-track container and does not support multiple audio tracks, which is a feature TS files commonly use for multi-language broadcasts. During this conversion, FFmpeg will select the first (default) audio stream from the TS file. If you need a specific language track from a multi-language broadcast TS, you would need to add a flag like '-map 0:a:1' to the FFmpeg command to select a different audio stream by index.
The video stream is completely discarded. M4B is a pure audio format designed for audiobooks and podcasts, so there is no video track in the output file. This is intentional — the resulting M4B file will be dramatically smaller than the source TS file because video typically accounts for 90% or more of a broadcast stream's data.
Subtitle tracks are dropped entirely, as M4B does not support subtitles. Chapter markers are also not automatically transferred from the TS container, because TS files rarely contain structured chapter metadata in the way M4B expects. The output M4B will be a single unbroken audio file. If you want chapters in your M4B, you would need to add chapter metadata separately using a tool like mp4chaps or ffmpeg metadata files after the initial conversion.
Replace '128k' in the '-b:a 128k' flag with your desired bitrate. For example, use '-b:a 192k' for near-transparent AAC quality on speech content, or '-b:a 256k' if the source is high-quality music audio from a broadcast. For spoken word content typical of audiobooks and radio, 128k AAC is generally sufficient, but 64k is acceptable if file size is a priority since AAC is efficient at low bitrates.
The '-movflags +faststart' flag moves the MP4/M4B container's metadata header to the beginning of the file instead of the end. For M4B audiobooks, this means a podcast app or audiobook player can begin reading chapter information and start playback before the entire file has finished downloading or transferring. Without this flag, some players must buffer the entire file before they can begin playback or display chapter navigation.
Technical Notes
TS files originating from broadcast television often contain AC-3 (Dolby Digital) audio rather than AAC, particularly from North American digital cable or over-the-air ATSC broadcasts. Converting AC-3 to AAC involves full transcoding — not a lossless remux — so some quality degradation is inherent. European DVB broadcasts are more likely to use AAC or MP2 audio. The M4B container is structurally identical to MP4 and M4A but uses the .m4b extension as a signal to Apple devices and compatible players (such as Overcast, Pocket Casts, and Apple Books) to enable bookmarking and chapter navigation features. The '-movflags +faststart' flag is particularly important for M4B files that may be streamed or transferred over a network rather than played from local storage. Note that this tool discards all video streams, subtitle streams, and secondary audio tracks from the TS source — only the primary audio track is preserved. If your TS file contains multiple audio tracks (e.g., original language plus dubbed tracks), only the default stream is selected unless you manually modify the FFmpeg command with explicit stream mapping.