Convert TS to AC3 — Free Online Tool
Extract and convert the AC3/Dolby Digital audio track from a MPEG-2 Transport Stream (.ts) file into a standalone AC3 file encoded at 192k bitrate. This is ideal for preserving broadcast-quality surround sound audio from TV recordings, live streams, or DVB captures without re-encoding the video.
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FFmpeg Command
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DownloadHow It Works
MPEG-2 Transport Streams frequently carry AC3 (Dolby Digital) audio tracks natively — particularly content captured from digital broadcast television, cable, or satellite. During this conversion, FFmpeg reads the .ts container, discards the video stream entirely, and transcodes (or in many cases effectively re-encodes) the selected audio stream into a raw AC3 bitstream file. If the source audio is already AC3, the data is repackaged with the target bitrate applied; if the source audio is AAC or another codec, it is decoded and then encoded into AC3 using Dolby Digital's lossy compression. The output is a headerless .ac3 file — a raw Dolby Digital bitstream — containing only audio, ready for use in DVD authoring, Blu-ray mastering, or broadcast workflows.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all the demuxing, decoding, encoding, and muxing operations needed to extract and convert audio from the .ts container into an AC3 bitstream. |
-i input.ts
|
Specifies the input MPEG-2 Transport Stream file. FFmpeg reads and demuxes the .ts container, making all of its audio, video, and data streams available for processing. |
-c:a ac3
|
Selects FFmpeg's built-in Dolby Digital encoder for the audio output stream. All audio from the .ts file — regardless of its original codec (AAC, MP2, AC3, etc.) — is decoded and re-encoded as AC3 using this encoder. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, which is the standard minimum for Dolby Digital and suitable for stereo broadcast audio. Higher values like 384k or 448k are recommended for 5.1 surround sound content. |
output.ac3
|
Defines the output filename with the .ac3 extension, which tells FFmpeg to write a raw Dolby Digital bitstream file without any container wrapper — the standard format expected by DVD authoring tools and broadcast encoding pipelines. |
Common Use Cases
- Extracting the Dolby Digital 5.1 surround sound audio track from a DVB or cable TV recording (.ts) for use in a home theater system or AV receiver
- Preparing broadcast-captured audio for DVD or Blu-ray authoring tools that require a standalone AC3 file as input
- Stripping the audio from a live stream or IPTV recording to archive just the commentary or soundtrack without storing the large video stream
- Converting a TV recording's audio track to AC3 for compatibility with legacy DVD players or set-top boxes that do not support AAC or Opus
- Isolating the AC3 audio from a multi-track .ts file (e.g., a broadcast with multiple language tracks) for import into a non-linear video editor or dubbing workflow
- Reducing storage size when only the audio content of a broadcast recording is needed, such as preserving a radio simulcast captured via a TV tuner
Frequently Asked Questions
Yes, there will be some generation loss. Even if the source .ts file contains an AC3 audio track, FFmpeg decodes it to PCM and then re-encodes it as AC3 at the specified bitrate rather than performing a lossless stream copy. If your goal is zero quality loss, you would need to use stream copying (-c:a copy) in FFmpeg directly on the command line, which bypasses re-encoding entirely — though this only works if the source audio is confirmed AC3 and the output bitrate matches.
For DVD authoring, 192k is the standard minimum and works well for stereo content, while 5.1 surround sound tracks are typically authored at 384k or 448k to preserve channel separation and dynamic range. Blu-ray supports AC3 up to 640k, though 448k is the most common choice for full 5.1 mixes. The default 192k in this tool is a safe starting point for stereo audio from broadcast recordings.
No. A raw AC3 bitstream file (.ac3) does not support metadata containers, so language tags, track names, and other descriptive metadata present in the .ts source are discarded during conversion. If metadata preservation is important, consider wrapping the AC3 audio in a container format like MKV or MP4 that supports metadata fields alongside the AC3 codec.
Replace the value after -b:a in the command with your desired bitrate. For example, to encode at 448k for a 5.1 surround mix, use: ffmpeg -i input.ts -c:a ac3 -b:a 448k output.ac3. Valid AC3 bitrates include 96k, 128k, 192k, 256k, 320k, 384k, 448k, and 640k — Dolby Digital's specification caps the format at 640k.
Yes. On Linux or macOS, you can use a shell loop: for f in *.ts; do ffmpeg -i "$f" -c:a ac3 -b:a 192k "${f%.ts}.ac3"; done. On Windows Command Prompt, use: for %f in (*.ts) do ffmpeg -i "%f" -c:a ac3 -b:a 192k "%~nf.ac3". This is particularly useful when archiving a season of broadcast recordings where you want to extract audio from every episode at once.
By default, FFmpeg selects the first audio track in the .ts file, which is typically the primary language or the default stream flagged by the broadcaster. To select a specific track — for example, the second audio stream — add -map 0:a:1 to the command: ffmpeg -i input.ts -map 0:a:1 -c:a ac3 -b:a 192k output.ac3. You can identify all available audio streams and their indices by running ffmpeg -i input.ts before conversion.
Technical Notes
MPEG-2 Transport Streams are designed for broadcast and streaming environments, and their audio payloads vary significantly depending on the source. DVB terrestrial and satellite recordings commonly carry AC3 or E-AC3 (Dolby Digital Plus) audio, while some broadcasters use MPEG-2 Audio (MP2) or AAC-LC. Because this tool uses FFmpeg's ac3 encoder (-c:a ac3), all source audio codecs are decoded to PCM first and then encoded into standard Dolby Digital, meaning the conversion is always a transcode — never a lossless remux. The output is a raw AC3 bitstream (.ac3), which lacks a container wrapper, making it incompatible with players that expect AC3 inside a container like MKV or MP4. AC3 is inherently limited to a maximum of 5.1 channels (6 channels); if the source .ts contains a 7.1 channel audio track (e.g., E-AC3 with Dolby Atmos), channels beyond 5.1 will be downmixed or dropped during encoding. The format also does not support chapters or subtitle streams, so any subtitle data in the .ts file is silently discarded. File sizes will be substantially smaller than the source .ts since video data is stripped and only compressed audio remains.