Cut and trim AC3 (Dolby Digital) audio files online. Extract segments from DVD and Blu-ray surround sound tracks.
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AC-3 (Dolby Digital, formally ATSC A/52) is the surround-sound codec Dolby introduced in 1991 and used as the audio backbone of DVD-Video, ATSC digital TV, and many Blu-ray secondary tracks. AC3 streams typically carry 5.1 surround at 384 or 448 kbps, with 640 kbps as the spec maximum (Blu-ray and games can use the full 640; DVD-Video caps at 448). Trimming an AC3 file lets you cut to the segment you actually need without re-encoding to a lossy intermediate.
| Property | AC-3 (Dolby Digital) | E-AC-3 (Dolby Digital Plus) | DTS |
|---|---|---|---|
| Standard | ATSC A/52 (1991) | ATSC A/52 Annex E (2005) | DTS Coherent Acoustics |
| Typical bitrate | 192-448 kbps | 192-1024 kbps | 754-1509 kbps on DVD |
| Max bitrate | 640 kbps | 6.144 Mbps | 1.5 Mbps (lossy core) |
| Max channels | 5.1 | 7.1 (and Atmos extension) | 5.1 (lossy) / 7.1 (HD) |
| Sample rate | 32 / 44.1 / 48 kHz | up to 48 kHz | 44.1 / 48 / 96 kHz |
| File extension | .ac3 | .eac3 | .dts |
| Where it's used | DVD-Video, ATSC TV, Blu-ray secondary | Streaming (Netflix, Disney+), Blu-ray | DVD, Blu-ray, theatres |
| Compatibility | Universal — every AVR since the late 1990s | Newer AVRs and TVs (post-2008) | Most AVRs, fewer TVs |
| Channels | Min usable bitrate | Recommended bitrate | DVD-spec max | Notes |
|---|---|---|---|---|
| 1.0 Mono | 64 kbps | 96-128 kbps | 448 kbps | Commentary, audiobook narration |
| 2.0 Stereo | 128 kbps | 192-224 kbps | 448 kbps | Stereo music, dialogue-only mixes |
| 5.1 Surround | 384 kbps | 384 kbps (DVD typical) or 448 kbps (DVD max) | 448 kbps | DVD/ATSC surround |
| 5.1 Surround (Blu-ray) | 384 kbps | 448-640 kbps | 640 kbps | Full AC-3 spec ceiling |
The 448 kbps figure for 5.1 isn't arbitrary — it's the DVD-Video maximum for AC-3, and it's what most commercial DVDs ship with. Going below 384 kbps for 5.1 produces audible artefacts on busy mixes; going above 448 takes you outside DVD compatibility.
Yes, as long as you leave "Audio Channel" on Original. The trim re-multiplexes (or re-encodes at your chosen bitrate) keeping all six channels — front L/R, center, LFE, surround L/R. If you set Audio Channel to Mono or Stereo the encoder will downmix to that layout, which is what you want for stereo playback but destructive for surround workflows. Confirm the source is actually 5.1 first; many "5.1" rips turn out to be 2.0 streams labelled as surround.
Match or exceed the source bitrate. For 5.1 DVD audio that's almost always 384 kbps (the DVD typical) or 448 kbps (the DVD-Video AC3 maximum). For ATSC broadcast 5.1 it's commonly 384 kbps. For stereo, 192-224 kbps is enough; for mono commentary, 96-128 kbps. Going below 384 kbps for 5.1 introduces surround compression artefacts — perceptible especially on bass and ambient effects. The full 640 kbps AC-3 ceiling only applies to Blu-ray and game-disc audio.
Three causes, in order of likelihood: (1) you re-encoded at a lower bitrate than the source — pick a higher Constant Bitrate or use Quality Preset Highest; (2) you set Audio Channel to Stereo and the encoder downmixed 5.1 to 2.0 with Lo/Ro or Lt/Rt fold-down; (3) you changed the sample rate from 48 kHz to 44.1 kHz, which forces resampling. To minimise quality loss, leave Audio Channel on Original, leave Sample Rate at 48000 Hz, and pick a bitrate ≥ source.
XConvert's trim re-encodes to apply your settings cleanly. Power users who want byte-exact, lossless AC3 cuts typically use FFmpeg's stream-copy mode (ffmpeg -ss <start> -t <duration> -i input.ac3 -c copy out.ac3) — but cuts can only land on AC-3 frame boundaries (~32 ms), and small leading silences may remain. For most workflows the re-encoded output at 384-448 kbps is indistinguishable from the source.
Keep AC3 if your downstream is DVD authoring (DVDStyler, DVD Architect), surround playback through an AVR/receiver, or video editing where surround channels matter. Convert if your downstream is general distribution: AC3 to MP3 for universal playback, AC3 to AAC for modern devices and smaller files at the same quality, AC3 to FLAC for lossless archival, or AC3 to WAV for editing in tools that don't decode AC3 natively.
Not from this page — upload an .ac3 file. To extract AC3 first, use MKV to AC3 or VOB to AC3 to demux the surround track, then bring the resulting .ac3 here to trim. The two-step approach (demux, then trim) is the cleanest way to keep the bitstream intact through DVD/Blu-ray rips.
48000 Hz is correct for almost every AC3 source. It's the DVD-Video standard, the ATSC broadcast standard, and what every commercial AC3 you'll encounter uses. AC-3 itself supports 32, 44.1, and 48 kHz, but 32 and 44.1 are rare in practice. Only change the sample rate if your downstream tool specifically needs 44.1 kHz (a few CD-mastering workflows do); resampling 48→44.1 kHz introduces a small amount of quality loss.
You can enter trim points down to the millisecond (HH:MM:SS.sss format, e.g. 00:01:23.456). Re-encoded output lands within one AC-3 frame of your chosen point — that's about 32 ms at 48 kHz. For most uses (extracting a song, cutting a scene's dialogue, creating a 30-second clip) that's well within "exact." If you need sample-accurate cuts to align with picture, do the cut in your NLE on the matching video track instead.
Yes. Upload multiple AC3 files; the trim window, bitrate, channel, and sample-rate settings apply to all of them in the same batch. Outputs download individually or as a ZIP. Useful for chopping intros off a series of broadcast captures or topping/tailing a DVD's chapter-by-chapter audio rips. To shrink AC3 files without trimming, use Compress AC3 instead.