Configure video encoding

You can configure the video encoding settings for a channel using the Admin panel. Video encoding settings include:

  • Video codec: The video codec determines the type of compression and decompression, and also affects the video quality.
  • Video encoding profile: This can be set to High, Main, or Baseline.
  • Frame size: The resolution applied to the channel when you stream, record, or output video to a confidence monitor. This can be set to automatically match the input video's resolution or set to a fixed resolution.
  • Key frame interval: How often a key frame that contains all the pixels is sent when streaming. The longer the key frame interval, the smaller the video file size (and vice versa).
  • Limit frame rate: You can limit the frame rate for the channel.
  • Bitrate: Increase or decrease image quality by increasing or decreasing the channel's Bitrate value. Video with a high level of motion and high resolution, such as sporting events, requires a higher bitrate.

Important considerations

  • For optimum system performance, the frame size of the channel should be set to match the frame size of your video input source to avoid scaling, see Optimum System Load.
  • The larger the channel's frame size, the more bandwidth is needed for streaming and the recorded files are bigger. Instead of using the same frame size as the original video source, you can configure a smaller frame size for the channel and let Unify downscale the video. For example, if the input video signal resolution is 1920×1080 (a 16:9 aspect ratio) and the channel's frame size is set to 1280×720, Unify downscales the video and streams/records the channel at the lower frame size, using less bandwidth and producing smaller recorded files.
  • If you have unchecked all the manual resizing and positioning boxes in the custom layout editor and you downscale the video source using the frame size setting on the Encoding tab (for example, select 1280×720 frame size for a full HD video source), then the source appears cropped within the frame instead of scaling to fit the frame.

You can add black bars around your video source by adjusting the frame size. For example, if your video source has a 16:9 widescreen/HD format but you need a 4:3 frame size on your output, Unify automatically adds black bars to the top and bottom of the frame if you choose a frame size for the channel that has a 4:3 aspect ratio.

There is some trade off between video quality and bandwidth size, depending on the encoding settings you choose. The following table lists some additional considerations when choosing video encoding settings.

Video encoding settings

Setting Description
H.264 H.264 provides high quality video while using low bandwidth.
Key frame interval
  • The key frame interval feature specifies how often a key frame (a frame that contains all the pixels) is sent when streaming the video. This setting also impacts how quickly a video moves through the frames when a viewer uses the search function of their media player.
  • Increasing the number of seconds between key frames can significantly reduce your bandwidth and system resource usage with minor impact to your video quality. A good rule of thumb is to keep the interval between 2 to 3 seconds and decrease the key frame interval as the motion increases.
  • Try different settings and note changes in the video quality. If your video quality is poor and jittery you may need to decrease the interval between key frames. If you have unlimited bandwidth and system resources you can choose an option to stream key frames only.
Frame rate

Frame rate reflects the number of images that are encoded per second. Reducing the frame rate for a channel reduces bandwidth usage, and vice versa.

The system's ability to maintain a set frame rate is based on several factors, for example:

  • overall system load affects the ability for the device to process pixels;
  • available network bandwidth;
  • the source and stream frame size (resolution);
  • the type of motion that is captured; and
  • number of users accessing the stream.

When adjusting the frame rate, you may need to try different values to achieve the best outcome.
Bitrate

In general, higher bitrates mean higher image quality, but more bandwidth is needed for streaming and video recordings are larger. You can set the bitrate to improve the image quality .

For example, an HD Blu-ray video is typically in the range of 20 Mbps, whereas a standard-definition DVD is usually 6 Mbps.

If you're unsure what bitrate value to use, start at 5000 kbps (slightly less than a typical DVD) and test to see how this looks for your viewers.

Configure video encoding for a channel using the Admin panel

  1. Log in to the Admin panel as admin, see Connect to the Admin panel.
  2. From the Channel(s) menu, select the channel and click Encoding. The encoding configuration page opens.
  3. Select a video Codec and do one of the following:
    • If H.264 is selected, select a Video encoding preset and a Video encoding profile.
    4. Item Options
    Video encoding profile

    Baseline: Choose this option when streaming to an application that requires robustness and cannot tolerate data loss, for example video-conferencing.

    Main: Choose this option for standard-definition broadcasts.

    High: This is the default. Choose this option when video is viewed for broadcast and disk storage applications, particularly for high definition television application such as Blu-ray disk storage format and HDTV broadcast service.
  4. Change the Limit frame rate. The default should be adequate in most applications. While decreasing the limit may improve system performance, you may need to test different values to balance video smoothness and processing power
  5. Change the Bitrate. You can increase or decrease image quality by increasing or decreasing the target Bitrate value. Video with a high level of motion and high resolution, such as a sporting event, requires a high bitrate.
  6. Click Apply.