Hardware-accelerated video encoding
Typically only supported with H264 video and often hit and miss
Hardware-accelerated video encoding is a tricky topic; it can sometimes work, but when it does, it doesn't always work as hoped.
It generally only works with H264 video, but it may work with other codecs in rare cases.
On a Windows PC, a Chromium-based browser offers your best chance of it working. Every month it seems the support for hardware encoding improves, which is great. The viewer just needs to request H264 video from your computer for it to have a chance of working. &codec=h264
If it works, in the video stats window (CTRL + Click), you'll see the video codec type to be listed as External Encoder, if the hardware acceleration is working. CPU load may not decrease always, and there isn't an easy way to tell which encoder is being used, but if it says the codec is h264, then it's likely still using just software.
Despite software using a lot of CPU, it offers better compatibility, fewer glitches, and technically can still handle dozens of video streams at a time if your CPU is fast enough. Hardware however can be finicky, where glitching is common and a hardware encoder typically can only support three video encoding sessions at a time.
What's really strange about hardware encoding on a PC is that it may actually use MORE CPU than the software-based openH264 alternative. If your goal is to save CPU power, a hardware encoder may just introduce more problems and offer no benefit at all; at least if encoding with a PC.
You can specify whether to use software or hardware H264 by changing the H264 profile ID; this can be specified, for example, using &h264profile=42e01f. 42e01f should trigger the OpenH264 software encoder, if available.
AMD systems, and some Intel systems, the default H264 hardware encoder will limit bitrates. Using VP8 or a software-based H264 encoder could allow for higher bitrates. The software VP8 encoder does seem to use more CPU than the H264 encoders, but it often is more stable, especially for screen shares.
On a MacOS system, Chrome may drop frame rates suddenly when using the H264 encoder.
On older versions of iOS, the H264 encoders can sometimes only support 720p30, while the VP8 software encoder on iOS can support 1080p. This recently changed with the iOS ~15, so newer iPhones can now support 1080p30 with H264. Your iPhone may still get very hot, so I am unsure if its actually hardware-accelerated; newer iPhones will do better than older. In the past, iOS devices were limited by how many videos could be encoded using H264, often just three total, so keep that in mind. This might have changed with newer iPhones however; untested.
Android
Many Android phones may not support H264 encoding in Chrome; this seems to vary based on the browser version, device chipset, and other factors. Trying to force H264 with such incompatible devices might result in no video, as the browser isn't always smart enough to know it isn't working. Chrome on Android doesn't seem to have a software-based H264 encoder. One user has reported that while using Chrome, Brave, and Firefox with their Samsung S23+ has poor performance with video encoding, likely due to using software encoding, Microsoft's Edge browser on Android did make use of the hardware encoding. Performance in this case was near comparable to an iPhone 14 Pro's encoding performance. Users with other devices that also use a Snapdragon GPU may wish to try MS Edge if having lackluster video encoding performance.
With non-Snapdragon GPUs, such as found in entry-level and some mid-range smartphones, the hardware H264 encoder may not be available regardless of browser used. Using software-based encoders may trigger overheating or CPU throttling, especially at higher resolutions, so if you are unable to trigger hardware-encoding on a slower Android device, you may need to be content with lower resolutions and bitrates.
On the Google Pixel the H264/VP8 encoder will glitch like crazy when used in Portrait mode, however it's glitch free when using the VP9 codec via software encoding.
NVIDIA
If a director, choosing to publish video to your group with H264 might reduce some CPU load, but if using an NVIDIA graphics card, you may end up forfeiting your ability to use NVENC encoding for RTMP or MKV file recording, since NVIDIA only offers typically three encoders. You can unlock this limit, but the benefits of using NVENC with VDO.Ninja often provides no benefits it seems over a software H264 option.
If using a CDN-service like meshcast.io, where a server redistributes the video to a large audience, H264 is highly compatible with most viewers, but this is only true for the OpenH264 profile ID 42e01f of H264. Hardware-encoded version of H264 may not be compatible with all browsers, such as with Safari viewers, so its not advised.
OperaGX tends to have issues with H264 encoding.
On the bright side, H264 is supported well on macOS, and it seems to use less CPU to decode than VP8. H264 on OBS 27.1 and older (for PC) offers lower packet-loss-induced "rainbow puke" than the VP8 codec, but this isn't a factor anymore with OBS 27.2 and newer. On PC, VP8 and H264 seem to use about the same CPU to decode in OBS. I'd advise you to do your own testing though.
Minimum resolutions
For many devices that are offering hardware accelerated encoding, a minimum or specific resolution is needed, else the device may switch back to software based encoding.
Sometimes this minimum resolution is 640x360, but other times it might be 1920x1080.
Embedded and Linux hardware-encoding support
If you're comfortable with Linux, basic publishing into VDO.Ninja is available using GStreamer and Python. The project is located here: https://github.com/steveseguin/raspberry_ninja/
Hardware encoding with multiple viewer per encoded stream is supported with this option, although features are limited. It is not for the faint of heart; generally this approach is still reserved for hobbyists, enthusiasts, and developers. A Raspberry Pi can publish 1080p30 to VDO.Ninja, and supports HDMI connected cameras; at least when using this project's code.
Code and quick start deployment images are available for the Raspberry Pi and NVIDIA Jetson embedded development boards, along with hardware-encoding support for those platforms.
Other Linux systems are support with the provided code, but it is up to you to ensure the hardware driver and configuration is setup correctly in those cases.
The project will hopefully keep expanding, to include more devices and operating systems.
H265 / HEVC / AV1
While AV1 hardware encoders are not common at the moment, they should be supported as they are adopted by browsers and hardware manufactures. &codec=av1
H265/HEVC however isn't commonly supported by browsers, although Thorium / Safari browsers may support it, it's not an officially supported option. You can give it a try however by using &codec=h265.
Update, as of December 2024: If running Chrome on PC, you try enabling H265 support by using the following command line to start your Chrome instance:
chrome.exe --enable-features=PlatformHEVCEncoderSupport,WebRtcAllowH265Receive,WebRtcAllowH265Send --force-fieldtrials=WebRTC-Video-H26xPacketBuffer/Enabled
You can see if your Chrome browser has H265 support enabled by going to https://vdo.ninja/whip and checking out the drop-down list of available codecs.
OBS WHIP and WHEP
With OBS v30 supporting WHIP output, it's now possible to stream video directly from OBS to VDO.Ninja via WebRTC with hardware accelerated encoding.
There are limitations with OBS's WHIP implementation in version 30 however, which may get addressed in the future, but without a server supporting OBS's WHIP output currently, this option is primarily limited for single point to point video distribution on controlled networks.
You can however use OBS's WHIP output with an SFU server however, such as Cloudflare's WHIP/WHEP server, and VDO.Ninja can ingest the WHEP output from that. This setup would work a bit like how Meshcast works with VDO.Ninja currently, except with the source being specified as WHEP-based, rather than from Meshcast.
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