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Visit the Vonage API Developer PortalAbout video codecs supported in OpenTok
The OpenTok platform leverages the WebRTC protocol and the real-time video codecs that are supported by WebRTC. In particular, the OpenTok platform supports the VP8, VP9, and H.264 video codecs.
Streams use the VP8 codec, which is supported on all clients, unless you set a preferred codec for the project that the session belongs to (see Setting the preferred video codec for a project.)
Across the broad ecosystem of devices and browsers that OpenTok supports there are varying levels of support for the VP8, VP9, and H.264 real-time video codecs. Some endpoints support all of the video codecs, and some just support one video codec. Depending on the type of application you are building and the types of browsers and devices your end users will use, your choice of preferred codec will change.
A video codec has two parts, an encoder and a decoder. It has the ability to encode (compress) incoming digital video frames from a webcam into a stream of binary data that can be sent over a network. It also has the ability to ingest a stream of binary data and decode (decompress) it into a flow of raw video frames that can be displayed on a screen. The mechanism for encoding and decoding the video is the codec standard and for the purpose of this page we are going to talk about two popular ones, VP8 and H.264.
The VP8 real-time video codec is a software codec. It can work well at lower bitrates and is a mature video codec in the context of WebRTC. As a software codec it can be instantiated as many times as is needed by the application within the limits of memory and CPU. The VP8 codec supports the OpenTok Scalable Video feature, which means it works well in large sessions with supported browsers and devices.
The H.264 real-time video codec is available in both hardware and software forms depending on the device. It is a relatively new codec in the context of WebRTC although it has a long history for streaming movies and video clips over the internet. Hardware codec support means that the core CPU of the device doesn’t have to work as hard to process the video, resulting in reduced CPU load. The number of hardware instances is device-dependent with iOS having the best support. Given that H.264 is a new codec for WebRTC and each device may have a different implementation, the quality can vary. As such, H.264 may not perform as well at lower bit-rates when compared to VP8. H.264 is not well suited to large sessions since it does not support the OpenTok Scalable Video feature.
The VP9 real-time codec is a relatively new codec. It is gaining more support among browser and hardware vendors. Despite increasing support, it still lacks the ubiquity of the other codecs.
The VP9 codec, like VP8, works well at lower bitrates than H.264. Moreover, VP9 requires even less bandwidth than VP8 to encode video. However, the improvements in compression comes with a tradeoff: encoding/decoding requires more CPU than VP8.
The VP9 codec is currently only supported in relayed sessions. As a result, the codec also lacks support for the OpenTok Scalable Video feature, which means it should not be used in large sessions.
You can set the preferred video codec for a project on the Project page of your Video API account.
In routed sessions (sessions that use the OpenTok Media Router), the preferred video codec is used for all clients in the session.
In relayed sessions, clients send streams directly to one another, and each publishing-subscribing pair tries to find a common video codec that they can both use. In this regard, the video codec used by the pair may be different to the preferred video codec setting.
If you do not set a preferred codec for a project, the VP8 codec, which is supported on all clients, is used.
The following tables list the real-time video codec capabilities of the supported OpenTok endpoints. Note that almost all devices have H.264 decoder support for streamed movies, however the tables below are focused on the real-time video codec (encode and decode) capabilities of the devices.
| Desktop browsers | VP8 | H.264 | VP9 |
|---|---|---|---|
| Chrome | Yes | Yes | Yes |
| Firefox | Yes | Yes | Yes |
| Safari | Yes 1 | Yes | Yes 2 |
| Edge | Yes | Yes | Yes |
| 1 VP8 is available in Safari 12.1+, which ships on macOS 10.14.4 and is also available for macOS 10.13.6 and 10.12.6. | |||
| 2 VP9 is available in Safari 17+ and is only supported on devices with hardware decoding (such as the M3 Macbook Pro). | |||
| Mobile browsers | VP8 | H.264 | VP9 |
|---|---|---|---|
| Chrome on Android | Yes | Partial 1 | Yes |
| Firefox on Android | Yes | Yes | Yes |
| Mobile Safari | Yes 2 | Yes | Yes 3 |
| Chrome/Firefox on iOS | Yes | Yes | Yes 4 |
| 1 Chrome on Android only supports H.264 on devices that contain the Qualcomm and Exynos chipsets and require Chrome 65 or higher | |||
| 2 VP8 is available in Safari on iOS 12.2+. | |||
| 3 VP9 is available in Safari 17+ and is only supported on devices with hardware decoding (such as the iPhone 15 Pro). | |||
| 4 VP9 is available in iOS 17+ and is only supported on devices with hardware decoding (such as the iPhone 15 Pro). | |||
| Native SDKs | VP8 | H.264 | VP9 ** |
|---|---|---|---|
| iOS SDK (2.12+) | Yes | Yes | Yes |
| Android SDK (2.13+) | Yes | Yes for most devices * | Yes |
| Windows SDK (2.13+) | Yes | Yes | Yes |
| Linux SDK | Yes | No | Yes |
| macOS SDK | Yes | No | Yes |
| * Hardware H.264 is supported on devices that contain the Qualcomm and Exynos chipsets, in addition to a subset of HiSilicon and MediaTek chipsets. Fallback to software H.264 is supported on Android M or higher. | |||
| ** VP9 support requires 2.27+ of the OpenTok native client SDKs (for Android, iOS, macOS, Linux, and Windows). | |||
| Codec/End-point | Chrome | Android Chrome | Firefox | Safari | Edge | iOS SDK | Android SDK | Windows SDK | macOS SDK | Linux SDK |
|---|---|---|---|---|---|---|---|---|---|---|
| VP8 | ||||||||||
| H.264 | 75% (*) | 99% (*) | ||||||||
| VP9 | (**) | |||||||||
| VP8 scalable video | ||||||||||
| H.264 scalable video | ||||||||||
| VP9 scalable video |
* Percentage of Android devices that support the codec
** VP9 is supported on Safari 17+ (desktop and iOS), but only on supported devices with hardware encoding, like the M3 Macbook and the iPhone 15 Pro.
Not all Android devices support the H.264 codec, and older versions of Safari do not support VP8. OpenTok.js and the OpenTok Android SDK include methods for checking the supported codecs available to the client.
The OT.getSupportedCodecs()
method returns a Promise that is resolved (on success) with an object that has two properties:
videoDecoders, an array of supported video codecs for decoding, and
videoEncoders, an array of supported video codecs for encoding.
The following example gets the list of supported codecs for encoding and decoding video streams:
(async () => {
try {
const supportedCodecs = await OT.getSupportedCodecs();
if (supportedCodecs.videoEncoders.indexOf('H264') < 0 && supportedCodecs.videoDecoders.indexOf('H264') < 0) {
// They do not support encoding or decoding H264 let's tell them to use a different browser
}
} catch(err) {
console.log(err);
}
})();
The
MediaUtils.SupportedCodecs.getSupportedCodecs(context) returns a
MediaUtils.SupportedCodecs object that that has two properties:
videoDecoders, an ArrayList of supported video codecs (defined by the
MediaUtils.VideoCodecType class) for decoding, and videoEncoders,
an ArrayList of supported video codecs (defined by the MediaUtils.VideoCodecType class)
for encoding.
The following example gets the list of supported codecs for encoding and decoding video streams:
MediaUtils.SupportedCodecs supportedCodecs =
MediaUtils.SupportedCodecs.getSupportedCodecs(context);
if (supportedCodecs.videoEncoders.indexOf(MediaUtils.VideoCodecType.VIDEO_CODEC_H264) < 0
&& supportedCodecs.videoDecoders.indexOf(MediaUtils.VideoCodecType.VIDEO_CODEC_H264) < 0)
{
// The device does not support encoding or decoding H264.
}
The main interoperability conflict is around Android devices, older versions of Safari, and Linux. VP8 works on all Android devices, both on Android Chrome and the OpenTok Android SDK, but H.264 codec support on Android is not ubiquitous. Older versions of Safari do not have VP8 codec support. The Linux SDK does not support H.264.
In OpenTok Routed sessions, the preferred video codec set in the Project settings is used for all clients in the session. In OpenTok Relayed sessions, clients send streams directly to one another, and each publishing-subscribing pair tries to find a common video codec that they can both use. In this regard, the video codec used by the pair may be different to the preferred video codec setting.
H.264, VP8 and VP9 can work well for endpoints in small sessions (for example, one to three participants). However, since there is no Scalable Video support with H.264 or VP9, we do not recommend either codec for large sessions.
Since the same VP8 video codec implementation is used on almost all endpoints the quality is roughly the same. VP8 works well at lower bitrates. In addition, OpenTok Scalable Video is available with VP8. Scalable Video significantly improves the video quality in larger sessions.
The quality of H.264 will vary across devices since the implementation of H.264 varies. In addition we have encountered differences in quality depending on the operating system version running on the device. The quality of H.264 at lower bitrates is generally not as good as VP8.
H.264 works well on iOS devices since they have good support for H.264 hardware acceleration. This reduces the CPU load and improves battery life.
VP9 has improved video quality over VP8. The quality improvements requires increased CPU load than VP8, though.
Here are the recommended video codec to use in some example scenarios:
In OpenTok sessions with two or three participants where interoperability with older versions of Safari is critical, use the H.264 video codec.
In OpenTok sessions with two or three participants where only iOS devices are involved, use the H.264 video codec to take advantage of the hardware acceleration.
Webinars and Large Classroom sessions should use the VP8 codec to take advantage of the OpenTok Scalable Video feature.
In OpenTok Sessions where support for all Android devices is critical, use the VP8 codec.
In OpenTok sessions with two participants, consider using the VP9 video codec.