Epiphan Pearl - Manual (Page 142)

Pearl User Guide Configure encoding
3. Click Encoding for the your channel; the encoding configuration page opens.
4. Scroll to the Key frame interval setting.
5. Click the Key frame interval drop-down box to choose how often a key frame (a frame that contains
all the pixels) is sent when streaming the video. The longer the key frame interval the smaller the video
file size, and vice versa.
6. If desired, 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.
7. If using H.264 of MPEG4 video codecs, 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.
8. If all your changes are complete, scroll to the bottom of the page and click Apply.
Table 20 Stream settings guidance
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 captured by the device per
second. Reducing the frame rate reduces bandwidth usage, and vice versa.
The system's ability to maintain a set frame rate is based on several
factors, for example:
l
overall system load affects the ability for the device to process
pixels;
l
available network bandwidth;
l
the source and stream frame size (resolution);
129