Encode

Overall config

The basic parameters of audio and video encoding are shown here, which are used to quickly and uniformly modify the encoding settings of all channels. After configuring the global parameters, click "save to local"the button to automatically set the parameters of all channels to be the same as the global parameters; if there are other encoders in the same area network, if you need to update the parameters of these encoders in batches, you can set the same group ID (the default is 0). After configuring the global parameters, you can click the "save to group"button to perform batch updates, as shown in the following figure:

Click "Start sync" button, the encoders in the group will automatically synchronize the encoding parameters according to the global parameters, and the synchronization progress will be fed back in real time in the interface.

Note: When you need to test the 4K encoding capability, please do not use the global configuration operation, it will exceed the system performance limit.

Encode config

This is consistent with the parameters in the "Global Configuration" section, but each one corresponds to an encoding channel, and each channel can be set to different encoding parameters. The first line of each channel parameter is the main stream encoding parameter, and the second line is the auxiliary stream encoding parameter.

Channel name: It can be displayed on pages such as "Running Status", which is easy to distinguish and manage.

Video size: The encoding resolution, which can be different from the input resolution. The common resolutions are enumerated in the list. If you need other resolutions, you can check the "Advanced encoding parameters" below.

Codec: Here you can choose the codec and profile of the video encoding

Rate control: You can choose CBR, VBR, AVBR, etc. If you are not sure which one to choose, it is recommended to use AVBR, which can get the best effect in most scenes.

Bitrate: Video bit rate, unit kbps, the setting range refer to the maximum bit rate in [Product Model Comparison Table]

Framerate: 1~60 frames

GOP: GOP is also called the key frame interval. Note that the unit here is seconds, and decimals are supported.

Enable: Master switch of the channel

Advanced encode config

Here you can set some advanced parameters about video encoding: Width, Height: Used to set the resolution that is not in the encoding parameter resolution list. After setting here, the encoding parameter list will display blank, which will not affect the operation.

Smart encode: Advanced P frame mode, which can improve the encoding quality when the bit rate remains unchanged, but will increase the key frame interval. SmartP is more suitable for static scenes, and DualP is more suitable for high dynamic scenes. Note that when this is turned on, it will cause the ROI function to fail.

minQP, maxQP: Used to set the quality range of video encoding in VBR rate control mode.

fixIQP, fixPQP: Used to set the quality of I frame and P frame in FixQP rate control mode.

Low latency: Enable or disable this function, it needs to be restarted to take effect. Turning on low-latency encoding can reduce the encoding delay, but it will lose the scaling ability, and the encoding resolution must be the same as the input resolution.

Video config

Full framerate deinterlace: LinkPi's exclusive function, when the input source is interlaced video, it can perform de-interlacing without losing frame rate, non-interlacing.

Rotate: This function can be used for the acquisition and processing of special input devices, such as mobile phones, etc., and can rotate the input image.

Crop: The input video can be trimmed. The unit of the input value is 'pixel'. Be careful not to exceed the range.

Audio config

Codec: Optional value "AAC, PCMA, MP3, MP2, Off", when "Off" is selected, the output stream only contains video.

Source: The audio source that can select the channel is HDMI or Line. Some models require an additional audio board for the line input.

Gain: Digital gain processing is performed on the input audio data. Due to the digital processing, the sound quality may be affected. It is recommended to adjust the volume at the source end as much as possible.

Samplerate: Optional values ​​"16k, 32k, 44.1k, 48k".

Channels: optional value "stereo, mono"

Bitrate: Audio encoding bit rate, in kbps, it is recommended to set 128 or higher for 48K stereo.

Network stream

It supports input network stream, and then converts the network stream to output, or transcodes the output. For example, most surveillance cameras on the market only support RTSP streams. In order to push the streams of surveillance cameras to RTMP-SERVER, it is necessary to transfer RTSP streams to RTMP streams.

The video encoding of the input network stream must be H264 or H265, and the audio must be AAC, PCMA, MP2, MP3. If you just transfer the stream, since no re-encoding is performed, the video quality and audio quality of the network stream will not be changed, nor the output bit rate.

When transcoding output, you need to turn on the "video decoding" switch, and then set the encoding output resolution, encoding method, bit rate control method, bit rate, frame rate, GOP interval and other parameters in the "coding parameter" column.

Stream url: For IPcam, usually the rtsp address. In fact, you can fill in the stream address of any protocol (rtmp/http/srt/udp, etc.), as long as it is supported by LinkSDK.

The srt protocol reference format issrt://ip:port?mode=caller&latency=50

framerate: Because some cameras do not describe the video frame rate in the protocol, the encoder cannot calculate the frame rate normally when performing transcoding frame rate control, and the user needs to fill in it manually. In most cases, it is enough to keep -1 here, and the encoder will automatically judge. When the decision cannot be made, it will give up the frame rate control and transcode according to the input frame rate.

Buffer mode: "Real-time": no buffer, decode immediately after receiving data; "General": with a small amount of buffer, decode according to the receiving rate; "Sync": with a large buffer, decode synchronously according to the timestamp;

Protocol: Only for rtsp setting, select "UDP, TCP", it is recommended to select "TCP", that is, rtp over rtsp mode, which can ensure data integrity and prevent packet loss.

Video decode: Video decoding switch, if you don't need to transcode, just convert the protocol (such as rtsp to rtmp), you don't need to open it here.

Audio codec: Audio decoding switch, if you don't need to transcode, just convert the protocol (such as rtsp to rtmp), you don't need to open it here.

Encode: The master switch of this network input channel.

Since the audio encoding and decoding of the HiSilicon solution will occupy more CPU resources, it is recommended that the audio decoding switch be turned on only when the audio needs to be transcoded or mixed into the Mix channel.