Configure encoding

You can modify the encoding settings for a channel. The encoding settings let you fine tune your channel recording or live stream. You can select a specific frame size, bitrate, audio or video codec, and more.

Channel encoding settings may be automatically overwritten when using the Pearl Nano with a Content Management System.

Codecs and file format compatibility

Pearl Nano supports the following codecs:

**Table 36 Supported video codecs **

Value	Description
H.264	H.264 provides high quality video while using low bandwidth.
H.265 (Pearl Nano only)	H.265 provides the highest quality video while using a comparatively low bandwidth. Compare the quality and required bandwidth relative to H.264.

Table 37 Supported audio codecs and bitrate guidance

Value	Description
AAC	AAC is comparable to MP3 and may even provide better sound quality at a similar sample bitrate. Supported sampling bitrate values are: 16, 22, 44 and 48K kHz. Setting the channel bitrate to match the audio source's bitrate provides the best sound quality and avoids audio resampling. Most digital signals (HDMI or SDI sources) use 48 kHz. Most digital signals (HDMI or SDI sources) use 48 kHz audio. For analog signals, 44 kHz provides a good quality audio sample. The maximum bitrate for mono encoding of a 44 kHz signal is 264 kbps. For stereo, 320 kbps is supported. Note that lower bitrates (e.g. 32 kbps) with a 44 kHz signal may result in distorted audio.
MP3	MP3 provides a common audio format for audio storage. Supported sampling bitrate values are: 22 kHz, 44 kHz and 48 kHz. Setting the channel bitrate to match the audio source's bitrate provides the best sound quality and avoids audio resampling. Most digital signals (HDMI or SDI sources) use 48 kHz. For analog signals, 44 kHz provides a good quality audio sample. Web browsers that use Flash (FLV) do not support 48 kHz MP3 audio. When selecting this encoding, you must use a web browser that supports HTML5 or a media player to preview your channel.
PCM	Pulse Code Modulation (PCM) is a standard for digital audio in computer and other devices such as, digital telephone systems. Setting the level to match the audio source's level provides the best sound quality and avoids audio resampling. Most digital signals (HDMI or SDI sources) use 48 kHz audio. For analog signals, 44 kHz provides a good quality audio sample.

Format compatibility

Not all streaming and recording protocols support all combinations of video and audio codecs. The following table lists any video/audio codec compatibility considerations for the supported streaming formats on Pearl Nano.

Table 38 Video/audio codecs and formats for streaming

Video Codec selected	Audio Codec selected	RTSP	FLV	MPEG-TS
H.264	No audio codec	✔	✔	✔
	PCM	✔	✔
	MP3	✔	✔	✔
	AAC	✔	✔	✔
H.265 (Pearl Nano only)	No audio codec	✔	▪	✔
	PCM	✔	▪	▪
	MP3	✔	▪	✔
	AAC	✔	▪	✔

The following table displays the compatibility between the video/audio codecs and the supported recording formats.

Table 39 Video/audio codecs and formats for recording

Video Codec selected	Audio Codec selected	MP4 and MP4-Fragmented	AVI	MOV	MPEG-TS
H.264 (and H.265 for Pearl Nano)	No audio codec	✔	✔	✔	✔
H.264 (and H.265 for Pearl Nano)	PCM	✔	✔	✔
H.264 (and H.265 for Pearl Nano)	MP3	✔	✔	✔	✔
H.264 (and H.265 for Pearl Nano)	AAC	✔	✔	✔	✔

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.
Pearl Nano supports H.264 and H.265 encoding.
Video encoding profile: This can be set to High, Main, or Baseline. Main is only available on Pearl Nano if H.265 codec is selected.
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.

By default, Pearl Nano automatically uses the incoming video source frame size as the frame size for streaming and recording when the channel has only one layout with a single video source. If you're channel has multiple video sources or layout, you must manually set a frame size for the channel. If you plan to switch layout during a live stream, a fixed frame rate is recommended. This avoids the stream from stopping and restarting due to frame size changes when switching between single-source layout that use different frame sizes.

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,
If your channel has a custom layout with only one source and your source and stream aspect ratios differ, then your source appears centered in the frame and matte bars are added automatically to the top and bottom (or left and right sides) of the frame to make up the difference.
If an SDI or HDMI video input source that is selected to display at the HDMI output port also appears in a custom layout for a channel, then the channel's encoding settings are used at the HDMI output. Changing the channel's frame rate will change the frame rate used at the output port for that video input. If the video source appears in multiple layout in different Channel, the one with the highest frame rate set in the encoding settings is used.
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 Pearl Nano 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, Pearl Nano 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, Pearl Nano 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.

Table 40 Video encoding settings

Setting	Description
H.264	H.264 provides high quality video while using low bandwidth.
H.265 (Pearl Nano only)	H.265 provides a high quality video while using a lower bandwidth. Compare the quality and required bandwidth relative to H.264.
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

Log in to the Admin panel as admin.
From the Channel menu, select the channel and click Encoding. The encoding configuration page opens.
Select a video Codec and do one of the following:
If H.264 (or H.265 on Pearl Nano) is selected, select a Video encoding preset and a Video encoding profile.

Item	Options
Video encoding preset	Software: This matches the default from previous generations of Epiphan products. Only select this if you need software encoding or X.264 encoding to match results created with previous generations of Epiphan products or firmware
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.

Item

Options

Video encoding preset

Software: This matches the default from previous generations of Epiphan products. Only select this if you need software encoding or X.264 encoding to match results created with previous generations of Epiphan products or firmware

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.

Configure the frame size, do the following:
Uncheck Use current signal resolution as the frame size.

Enabling Use current signal resolution as the frame size is not recommended if the video input resolution changes frequently. An unstable cable or other disturbance that causes the resolution of the video input signal to change during a live stream can cause the stream to drop. Unchecking this feature helps prevent that.

Select a Frame size from the list of options or enter a custom frame size in pixels.
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
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.
Click Apply.

Configure audio encoding

If your channel includes audio sources in any of the layout, then AAC 48 kHz is set as the default audio codec for the channel. You can choose a different audio codec for a channel using the Admin panel. The following table lists the supported audio codecs and bitrates.

Table 41 Supported Audio codecs and bitrates

Value	Description
AAC	The AAC (default) audio codec is comparable to MP3 and may produce better sound quality with a similar bitrate. Supported values are 16, 22, 44 and 48K kHz. Most digital signals (HDMI or SDI sources) use 48 kHz audio. Matching the encoded level with the source level provides the best sound quality by avoiding audio resampling. For analog signals, 44 kHz provides higher sampling. The maximum bitrate for mono encoding of a 44 kHz signal is 264 kbps. For stereo, 320 kbps is supported. Note that lower bitrates (e.g. 32 kbps) with a 44 kHz signal may result in distorted audio.
MP3	MP3 provides a common audio format for audio storage. Supported values are 22 kHz, 44 kHz and 48 kHz. Most digital signals (HDMI or SDI sources) use 48 kHz audio. Matching the encoded level with the source level provides the best sound quality by avoiding audio resampling. For analog signals, 44 kHz provides higher sampling. Flash (FLV) doesn't support 48 kHz MP3 audio. When selecting this value you'll need to use a media player to preview your channel.
PCM	Pulse Code Modulation (PCM) is a standard for digital audio in computer and other devices such as, digital telephone systems. Most digital signals (HDMI or SDI sources) use 48 kHz audio. Matching the encoded level with the source level provides the best sound quality by avoiding audio resampling. Flash (FLV) doesn't support 48 kHz PCM audio. When selecting this value you'll need to use a media player to preview your channel.

Change the audio codec for a channel using the Admin panel

Log in to the Admin panel as admin.
From the Channel menu, select the channel and click Encoding. The encoding configuration page opens.
In the Audio settings, ensure that Enable audio is checked to include audio in the channel.
From the ** Audio format** drop down, select an audio codec.
From the** Audio Channel** drop down, choose mono or stereo (default).

Choose Mono to have left and right stereo Channel combined so that when you listen to the streamed or recorded audio, the same blended sound comes through both the left and right Channel.

If you have only one mono analog input, use the left jack and select mono encoding to have the same sound come from both the left and right Channel. (If stereo sound is chosen, the sound will only come through on the left channel.

Pearl Nano - XLR/RCA1

From the Audio bitrate drop down, choose a bitrate. For stereo audio, we recommend 256 kbps or 320 kbps.
Click Apply.