Audio
Audio codec, channel configuration, and sidecar dub/descriptive audio requirements.
Scope
The audio requirements in this document apply regardless of delivery method. Channel configuration, channel labeling, and language and locale matching requirements are the same for:
- Audio multiplexed (muxed) into the video file container
- Audio delivered as a sidecar file separate from the video
Both delivery paths must conform to the same channel configuration and labeling rules described below.
Audio Codec & Sample Rate
- PCM 16-Bit or 24-Bit, 48kHz audio at the highest available bitrate is preferred.
- Dolby AC3 audio is supported.
Roku prefers to receive 5.1 Surround and Stereo audio whenever possible.
Channel Configuration & Labeling
All channels must be clearly labeled for position and language. The label format depends on the file format. This applies to both muxed and sidecar audio; see Scope.
5.1 Surround + 2.0 Stereo (preferred)
| Channel | Label |
|---|---|
| Channel 1 | Left Front (L) |
| Channel 2 | Right Front (R) |
| Channel 3 | Center (C) |
| Channel 4 | LFE (Lfe) |
| Channel 5 | Left Surround (Ls) |
| Channel 6 | Right Surround (Rs) |
| Channel 7 | Stereo Left (SL) |
| Channel 8 | Stereo Right (SR) |
5.1 Surround only
Acceptable if 5.1 + Stereo is not available.
| Channel | Label |
|---|---|
| Channel 1 | Left Front (L) |
| Channel 2 | Right Front (R) |
| Channel 3 | Center (C) |
| Channel 4 | LFE (Lfe) |
| Channel 5 | Left Surround (Ls) |
| Channel 6 | Right Surround (Rs) |
2.0 Stereo only
Acceptable if 5.1 + Stereo and 5.1 Surround only are not available.
| Channel | Label |
|---|---|
| Channel 1 | Stereo Left (SL) |
| Channel 2 | Stereo Right (SR) |
Sidecar Audio Deliverables
If the audio is not in the primary language of the distribution territory, the delivery must include a dub, subtitles, or both in that territory's primary language.
- Localized audio tracks may be multiplexed into the video file, or delivered as a single interleaved sidecar audio file.
- Regardless of delivery method, all localized audio tracks must be delivered as a full audio mix. Roku does not support dialogue-only dub tracks.
- Sidecar audio must be delivered as a single interleaved file. Roku does not support discrete single-channel files.
- Sidecar audio must sync to the video source file delivered to Roku.
- Roku supports one sidecar audio dub file per language.
- Sidecar audio must follow the same channel configuration and labeling rules defined in Channel Configuration & Labeling above.
Deliver sidecar audio at the highest bitrate and sampling rate available.
Supported Sidecar Audio Formats
| Container | Codecs | Extension |
|---|---|---|
| WAV (preferred) | PCM GSM | .wav |
| MOV (must not include a video track) | AAC MP3 PCM | .mov |
| MP4 (MPEG-4) (must not include a video track) | AAC FLAC | .mp4 |
| MPEG-1 Layer 3 | MP3 | .mp3 |
| OGA | FLAC Opus Vorbis | .ogg |
Descriptive Audio
Descriptive audio is an alternative audio track for viewers who are blind or have low vision, as described in the FCC Audio Description requirements.
- Roku strongly prefers to receive descriptive audio tracks wherever available.
- Descriptive audio deliveries must follow the same requirements outlined in Sidecar Audio Deliverables above.
- Descriptive audio must be provided in the same language and locale as its companion standard (non-descriptive) audio track for that language.
- The audio language code of the descriptive audio track must exactly match the audio language code of its companion standard audio track. For example, a descriptive track paired with a standard track coded
en-USmust also be codeden-US. Codes such asen,en-GB, or any other variant do not match.
Audio Channel Layout Hints
If a video file cannot include embedded audio channel labels, an audio layout hint must be provided in the delivery metadata for that video. This applies to muxed audio only where in-file labeling is not possible; it does not replace the labeling requirement for sidecar files.
| Descriptor | Definition |
|---|---|
stereoOnly | 2-channel stereo audio only. May be delivered on a single track or 2 discrete tracks. |
surroundOnly | 6-channel 5.1 surround audio only. May be delivered on a single track or 6 discrete tracks. |
stereoPlusSurround | 8-channel audio with stereo on channels 1–2, followed by 5.1 surround on channels 3–8. |
surroundPlusStereo | 8-channel audio with 5.1 surround on channels 1–6, followed by stereo on channels 7–8. |
Glossary
| Term | Definition |
|---|---|
| Muxed / Multiplexed | Audio combined into the same file container as the video, rather than delivered separately. |
| Sidecar file | An audio or subtitle file delivered alongside (not embedded in) the video file, mapped to it via metadata. |
| Interleaved | Multiple audio channels combined into a single file, as opposed to separate discrete files per channel. |
| Discrete channel | An individual audio channel delivered as its own separate file/track rather than combined with others. |
| LFE | Low-Frequency Effects channel: the ".1" in 5.1 surround, typically routed to a subwoofer. |
| Full audio mix | A complete mixed audio track (dialogue, music, effects), as opposed to a dialogue-only or partial track. |
| Language code | A standardized code identifying language and, optionally, regional locale (e.g., en-US, es-MX). |
Updated about 5 hours ago