Deliver your HLS low-latency streams to viewers faster, with a target latency of about 10 seconds. This delay is significantly lower than regular streams and represents the time from capturing input to its display on the viewing platform.
Learn how to configure your HLS stream for passthrough and optimize OBS settings to achieve this goal.
In this article:
Considerations
Latency depends on many factors, including your viewer's geographic location and their internet connectivity speed. However, with Ravnur's optimized player configuration and CDN delivery, it is possible to achieve a target latency in the range of 9-12 seconds.
- DVR (Digital Video Recording) is disabled during low-latency streaming. Viewers will see just the real-time view (also referred to as edge) of the event.
- Despite the lack of DVR during the stream, the event can be recorded for future Video on Demand (VOD) availability once it is finished.
- Low-latency streaming is not supported for MPEG-DASH live sources.
- Both RTMP and SRT protocols are compatible with low-latency streaming.
- Low-latency streaming is available only for Passthrough live sources. Adaptive Bitrate live sources, such as Standard 720p and Premium 1080p, are not supported.
Before starting
Follow these steps to add a live source for low-latency streaming:
1. Create a live source:
1.1. Choose RMS as the live source type.
1.2. Set Standard Passthrough as the encoding option.
1.3. Select RTMP or SRT as the ingest stream protocol.
2. Add a title that clearly indicates the source type and settings, such as Low latency passthrough. Optionally, include a description to provide additional details.
3. Check the Enable low latency checkbox to activate low-latency streaming.
Alternatively, you can modify an existing live source to enable low-latency mode: select the live source settings and check the Enable low latency option.
Configure OBS
Use these OBS settings to reduce latency while keeping the stream quality. SRT or RTMP passthrough types are configured the same way:
1. Launch OBS > Settings > Output > Output mode: Advanced.
2. Select the following Video encoder option:
| OS | Option |
|---|---|
| MacOS |
Apple VT H264 Hardware Encoder |
| Windows |
Recommended: NVIDIA NVENC H.264 Alternative: QuickSync H.264 |
3. Select the following Rate control option:
| OS | Option |
|---|---|
| MacOS |
CRF (Constant Rate Factor) |
| Windows |
VBR (Variable Bitrate) |
4. Apply these universal settings for both OS:
| Setting | Value |
|---|---|
| Bitrate |
Minimal: |
| Keyframe interval |
2 sThis is a mandatory value to achieve low latency. |
| Preset | P4: Medium (Medium Quality) |
| Multipass Mode | Single PassThis is a mandatory value to achieve low latency. |
| Profile | High |
| Max B-Frames |
0B-frames (Bidirectional-predictive Frames) increase latency during the encoding and decoding process. Setting the value to “0” is recommended. |
The following screenshot displays the sample settings for Windows (NVIDIA GPU) output:
Go live
After configuring OBS, set up the channel using the source you created. Next, schedule your live event with this source.
At this point, you are ready to preview and go live.
To validate latency, compare the real-time preview in the Control Room with the stream on a viewer's device. Measure the delay between a visible event and its appearance in the player.
Tip for a content creator: Keep in mind that home networks, especially in urban areas, and mobile connections may not reliably support low-latency streaming. Consider using a high-speed internet provider.
You’re now ready to deliver faster, low-latency live streams to your viewers.