Recommended live stream settings for global-contribute.live-video.net
Reducing Latency
To prepare your streaming application for low-latency streaming, do the following. (Note: not all these options are available on every streaming application.)
- On the video encoder, set
IDR/Keyframeto a 2-second interval (or 1 second, for even lower end-to-end latency).
IfIDR/Keyframeis 2 seconds, stream-start latency will be approximately 9-12 seconds. IfIDR/Keyframeis 1 second, stream-start latency will be approximately 6-8 seconds. Your video will be available for viewers and auto-recording only after the initial stream-start latency period.
The shorter, 1-second keyframe interval has some QoS tradeoffs. It can cause the player’s adaptive bitrate streaming (ABR) to switch resolution more often; the segment size is smaller, so the ABR check happens more often. Buffering may increase due to increased resolution-switching and/or if the viewer’s network cannot download the segments fast enough. Evaluate these tradeoffs when deciding between a 1- or 2-second keyframe interval. - If available, set your encoder to zero-latency tuning within an x264 configuration.
- Ensure that buffer size (VBV) does not exceed the average bitrate (kilobits-per-second) of the stream.
Avoid Third-Party Streaming/Forwarding Services
We strongly recommend you do not use third-party service to restream or forward content to InvitePeople. This will incur extra latency. For low latency, stream directly to InvitePeople.
Encoder Settings
Stream Ingest: Codecs, RTMPS, and Port 443
Codecs: InvitePeople supports H.264 for video and AAC (LC) for audio.
InvitePeople supports the most common secure ingest protocol used in streaming software and hardware, RTMPS (Real-Time Messaging Protocol over a TLS/SSL connection). InvitePeople streaming and playback require TLS version 1.2 or later.
Your video encoder must connect to InvitePeople ingest over the RTMPS protocol associated with outbound port 443/TCP. To ensure this, include the port in your ingest URL path; for example:
rtmps://<ingest-server>:443/app/<stream-key>
Resolution/Bitrate/FPS
The stream’s resolution largely determines its bitrate and frame rate (frames-per-second, or FPS). Use the following guidelines; these are our recommendations. Note the resolutions shown below are landscape orientation (horizontal x vertical), so reverse these for portrait orientation.
| High Quality (Full HD) 1080p (1920×1080) | Good Quality (HD) 720p (1280×720) | Acceptable Quality (SD) 480p (852×480) | |
|---|---|---|---|
| Bitrate | Up to 8500 Kbps Recommended ~ 5000 Kbps |
Up to 4500 Kbps | Up to 1500 Kbps |
| FPS | 25, 30, 50 or 60 | 25, 30, 50 or 60 | 25 or 30 |
| Keyframe interval | 2 seconds | 2 seconds | 2 seconds |
Bitrate, FPS, and resolution are interrelated. The optimal values depend on circumstances and can be complicated to determine. Our best guidance is to start with the values above and experiment if desired. The goal is clear and smooth motion of video components during streaming and good resolution within the available bandwidth. Increasing frame rate and/or resolution increases overall video quality, but this is necessarily limited by bandwidth.
InvitePeople supports framerates up to 60 FPS. The higher the framerate, the better the quality — as long as there is adequate bitrate bandwidth.
Video Settings
We recommend the following settings. They are available to most H.264 video-encoding software or hardware APIs.
- On the video encoder, set
IDR/Keyframeto a 2-second interval (or 1 second, for even lower end-to-end latency). - H.264 level: Main
- Scene change: Off (preferred)
- Chroma subsample: YUV420P
- CABAC: Preferred
Audio Settings
We support the following settings:
- Codec: AAC (LC)
- Bitrate: anything up to 320 Kbps
- Sample rate: 44.1 Khz or 48 Khz (it is best to match your production audio flow)
- Channels: Maximum 2 – Stereo (1: mono or 2: stereo audio channel support)
Use CBR, Not VBR
Always use CBR (Constant BitRate), not VBR (Variable BitRate), as the rate-control method for encoders. CBR is better suited for the fixed-bandwidth nature of networks, and it produces more predictable, stable video playback for client devices. With a consistent bitrate, it is easy for viewers to select a quality level that their connection can handle over time.
Depending on the complexity of the scene, VBR can result in spikes in bitrate, which can cause frame drops before the video reaches InvitePeople and/or buffering in client players.
We strongly recommend you only use CBR. If you use VBR, your streams will be more subject to buffering and playback that is not smooth.
Use Progressive Signals
Use progressive signal flows; avoid any interlaced video in production flow and/or encoding. Progressive stream signals yield much better playback quality displaying a whole frame at a time, avoiding any motion artifacting that is produced when displaying an interlaced signal.
Network Requirements
You must have a stable internet connection that can maintain an adequate, constant upload stream. An unstable internet connection could result in stream stuttering and lagging for your viewers.
Use wired connections. WiFi and LTE connections can be spotty or suffer from interference or latency due to bad QoS/packet-queue prioritization. Whenever possible, rely on a hardwired connection for streams.
Plan to allocate 50% more bandwidth than the minimum required. The overhead is added to compensate for the bitrate fluctuations in encoding of a video bitstream.
Use a dedicated Internet VLAN to encoding machines. Keeping the encoder on a separate network prevents potentially disruptive effects, including: pollution by traffic, bandwidth bottlenecks and adverse security factors.