ChromeOS Compatible - 3.5mm Headset Specification v1.3
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Version: 1.3.1
Last updated: 2024-06-17
Legend
| Product Verb |
Development Action |
| "MUST" |
Mandatory product requirement |
| "SHOULD" |
Optional recommendation |
| "MAY" |
Nice to have |
Overview
This document describes the requirements a ChromeOS Compatible wired headset
meets. This specification is not for WWCB products, nor for a product designed
and certified together with a Chromebook.
3.5mm audio connector hardware specifications
Plug
- Mechanical
- 4 conductor 3.5mm plug
- Pinout order
- CTIA (LRGM) - Recommended
- OMTP(LRMG) - Optional
- Electrical
- Ear speaker impedance
- Mic equivalent DC resistance
(Source:
https://source.android.com/devices/accessories/headset/plug-headset-spec )
Audio Quality
Capture Path - Mute
- If there is any interface for users to mute the audio device, it must
- Maintain the mute state in a way that is not affected by:
- Opening and closing the device.
- Switching to another input device.
- If the user presses the mute button on the headset or ChromeOS, the
mute state must change.
- If the mute state changes, the mute state indicator (eg:LED) on the
headset must change.
Audio Latency
Latency
- Output Latency
- Audio playback must begin ≤500 ms after a user action that
initiates playback.
- May request a waiver if the device OEM can prove that no echo is
introduced when it fails this requirement.
A/V Sync
- Audio playback should be synchronized with video playback. Audio playback
may lead the video by ≤25 ms or trail the video by ≤95 ms.
Revision History
| Date |
Version |
Notes |
| 2024-06-17 |
1.3.1 |
ChromeOS Compatible spec derived. Initial Partner Site Publication. |
| 2022-09-01 |
1.3 |
Related WWCB specification v1.3 |
| 2022-06-06 |
1.2 |
Related WWCB specification v1.2 |
| 2020-10-14 |
1.1 |
Related WWCB specification v1.1 |
| 2020-09-23 |
1.0 |
Related WWCB specification created. |
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2024-12-18 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2024-12-18 UTC."],[[["\u003cp\u003eThis specification outlines the requirements for wired headsets compatible with ChromeOS, focusing on hardware and audio quality.\u003c/p\u003e\n"],["\u003cp\u003eThe headset must use a 4 conductor 3.5mm plug with CTIA pinout (LRGM) recommended and specific impedance ranges for Play/Pause, Volume Up, and Volume Down buttons.\u003c/p\u003e\n"],["\u003cp\u003eA mute functionality, if present, must maintain its state across device interactions, visibly indicated by an LED or similar.\u003c/p\u003e\n"],["\u003cp\u003eAudio output latency should be less than 500ms after user action, with potential waivers for OEMs demonstrating echo-free performance.\u003c/p\u003e\n"],["\u003cp\u003eAudio-video synchronization is essential, with audio leading video by a maximum of 25ms or trailing by a maximum of 95ms.\u003c/p\u003e\n"]]],[],null,["# ChromeOS Compatible - 3.5mm Headset Specification v1.3\n\nVersion: 1.3.1 \n\nLast updated: 2024-06-17\n\nLegend\n------\n\n| Product Verb | Development Action |\n|--------------|-------------------------------|\n| \"MUST\" | Mandatory product requirement |\n| \"SHOULD\" | Optional recommendation |\n| \"MAY\" | Nice to have |\n\n### Overview\n\nThis document describes the requirements a ChromeOS Compatible wired headset\nmeets. This specification is not for WWCB products, nor for a product designed\nand certified together with a Chromebook.\n\n3.5mm audio connector hardware specifications\n---------------------------------------------\n\n### Plug\n\n- Mechanical\n - 4 conductor 3.5mm plug\n - Pinout order\n - CTIA (LRGM) - Recommended\n - OMTP(LRMG) - Optional\n- Electrical\n - Ear speaker impedance\n - ≥ 16 Ω\n - Mic equivalent DC resistance\n - ≥ 1000 Ω\n\n### Buttons\n\n- Only buttons listed below are allowed\n - Play/Pause (Function A)\n - Volume up (Function B)\n - Volume down (Function C)\n- **Mandatory**\n - No answer/hang up button.\n - The OS doesn't support it.\n- The control function equivalent Impedance\\* must satisfy the requirements in\n the table below:\n\n | Function | Impedance^[1](#fn1)^ range |\n |--------------------------|----------------------------|\n | Play/Pause (Function A) | \\[0, 70\\] Ω |\n | Volume up (Function B) | \\[210, 290\\] Ω |\n | Volume down (Function C) | \\[370, 680\\] Ω |\n\n(Source:\nhttps://source.android.com/devices/accessories/headset/plug-headset-spec )\n\nAudio Quality\n-------------\n\n### Capture Path - Mute\n\n- If there is any interface for users to mute the audio device, it must\n - Maintain the mute state in a way that is not affected by:\n - Opening and closing the device.\n - Switching to another input device.\n- If the user presses the mute button on the headset or ChromeOS, the mute state must change.\n- If the mute state changes, the mute state indicator (eg:LED) on the headset must change.\n\nAudio Latency\n-------------\n\n### Latency\n\n- Output Latency\n - Audio playback must begin ≤500 ms after a user action that initiates playback.\n - May request a waiver if the device OEM can prove that no echo is introduced when it fails this requirement.\n\n### A/V Sync\n\n- Audio playback should be synchronized with video playback. Audio playback may lead the video by ≤25 ms or trail the video by ≤95 ms.\n\nRevision History\n----------------\n\n| Date | Version | Notes |\n|------------|---------|---------------------------------------------------------------------|\n| 2024-06-17 | 1.3.1 | ChromeOS Compatible spec derived. Initial Partner Site Publication. |\n| 2022-09-01 | 1.3 | Related WWCB specification v1.3 |\n| 2022-06-06 | 1.2 | Related WWCB specification v1.2 |\n| 2020-10-14 | 1.1 | Related WWCB specification v1.1 |\n| 2020-09-23 | 1.0 | Related WWCB specification created. |\n\n*** ** * ** ***\n\n1. The equivalent impedance is measured from positive mic terminal to GND\n when button is pressed with 2.2 V mic bias applied through 2.2 kΩ resistor. [↩](#fnref1)"]]
