Epiphan Pearl Mini Live Video Production System - Manual (Page 426)

Limitations and known issues
This section includes known issues or limitations that affect functionality or usability and ways that you can work
around these limitations.
Affecting encoding
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Limitation : When Pearl Mini is overloaded, video frames or audio samples can be dropped causing variable
frame rate and audio cracks.
Workaround : Pearl Mini is a powerful system capable of many simultaneous tasks, but like any other
computing device, it has finite resources. If this problem is observed, check the CPU load from your system's
Info page.
To reduce system load, do any of the following: disconnect unused video displays from Pearl Mini's video
output ports, delete unused channels and unused layouts, or reduce the complexity of layouts by scaling at the
source instead of having the system scale, or reduce the number of sources in layouts, or reduce the frame size
or frame rate for channels displayed on the video output ports. Note that actions performed in the Admin
panel and Epiphan Live can increase overhead (such as adding channels/sources to Epiphan Live's Dashboard
preview panels), as can switching layouts via Pearl Mini's touch screen.
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Encoding video at 60 fps with either 16 kHz or 22 kHz AAC audio can result in some dropped video frames.
Workaround : Select another video frame rate, a different audio sampling rate, or choose MP3 audio.
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Configuring very low frame rates such as 1 fps encoding with a high bitrate setting (e.g. 7000 kbps) results in
poor video quality.
Workaround : Allow Pearl Mini to automatically select the best bitrate setting. For 1 fps, this results in a bitrate
of about 1180 kbps.
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Some audio distortion is heard on video output port using PCM 22 kHz encoding or very low frame rate (1-5
fps).
Workaround : For best results, use AAC 48 kHz or PCM 48 kHz audio encoding and encode the channel at
higher than 5 frames per second.
Affecting streaming and recording
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Streaming status on the touch screen does not include Wowza Streaming Cloud transcoder settings.
Workaround : Start the transcoder from the Pearl Mini or Wowza web UI.
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Interlaced SDI capture is sometimes shifted downwards, resulting in a small green line at the top of the video.
Workaround : This issue varies with different sources. If it is affecting your capture, the best solution is to crop
out the green line in your layout.
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The ability to perform an FTP Delete cannot be disabled, even after using the Disable FTP Delete command
in the FTP session.
Workaround : Ensure that access to control of the FTP session is restricted to those aware of decisions about
deleting the stream.
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Extracting tracks from an .MP4 recording when there isn't enough storage space for the extracted files causes
the extracted files to become corrupted.