HDMI Encoder¶

The HDMI encoder as part of Mcaster is designed to receive video signals from medium and entry-level consoles and prepare content for further transmission via various interfaces: SDI, NDI, ST2110 or already in compressed form.

Recommended Hardware¶

For HDMI capture, entry-level Blackmagic Decklink cards are recommended. They have the following characteristics:

• Affordable cost
• Sufficient reliability for short-term capture
• Ease of setup and use

Drivers¶

All necessary drivers for working with the HDMI encoder are already included in the InfraMedia distribution and do not require additional installation.

HDMI Capture Setup¶

To check available capture devices, run the command:

BlackmagicFirmwareUpdater status

If successful, you will see a list of available capture devices.

Basic Stream Configuration¶

Configure the stream for HDMI capture as follows:

stream sdi {
  input decklink://0;
}

Mcaster will connect to the specified first device (0) and launch autoconfiguration to search for active resolution.

Manual Mode Configuration¶

Some Decklink models do not support automatic search for active resolution. For them, it is necessary to specify the mode manually using the mode and vinput options.

For example, for Intensity Pro with a connected HDMI source of 720p and 50 fps:

stream sdi {
  input decklink://0 mode=hp50 vinput=hdmi;
}

Web Interface Configuration¶

You can configure HDMI capture parameters through the Mcaster UI:

1. Go to the Streams tab on the Media page in the side menu
2. Open the settings of a stream configured for HDMI capture (with source decklink://0)
3. Go to the Input tab and click Options
4. Set the necessary parameter values in the Decklink section

HDMI Stream Transcoding¶

To transcode the captured HDMI stream, add the transcoder directive to the stream settings:

stream sdi {
  input decklink://0;
  transcoder vb=3096k ab=64k;
}

Benefits of the New Approach¶

• Improved video quality by avoiding double transcoding
• Server resource savings
• "Seamless" switching between HDMI and other stream sources
• Ease of configuration through the web interface

Deinterlacing¶

To improve video quality, Mcaster can eliminate interlacing in progressive streams using the CUDA yadif deinterlacing method:

stream test {
  input decklink://1 vinput=sdi;
  transcoder vb=4000k hw=nvenc preset=slow fps=50 deinterlace=yadif ab=128k;
}

SD Video Capture¶

Mcaster supports video with non-square pixels (anamorphic video) when capturing from HDMI cards. This is especially important for SD (standard definition) quality.

To preserve proportions in the output video without image distortion, specify the sar of the input stream:

stream test {
  input decklink://1 vinput=hdmi sar=16:11;
}

Mcaster calculates the output video resolution based on sar. For example, with sar=16:11, incoming anamorphic video 720x576 will pass through Mcaster with 1048x576 resolution.

Duplex Mode Operation¶

Mcaster allows setting duplex mode for Decklink HDMI cards. In this mode, ports can be used individually for input or output, or as a combination of input and output.

For more information on setting up duplex mode, see Duplex Mode Operation.

Limitations and Recommendations¶

Time Limitations¶

Blackmagic Decklink cards have limitations during long-term use:

• High probability of timecode shifts
• Incorrect timecode transmission
• Instability during 24/7 operation

Recommendations for Critical Systems¶

For use in mission-critical systems where reliability and stability are important, it is recommended to use Dektec cards instead of Blackmagic Decklink.

Testing New Cards¶

If you want to test other capture cards for addition to the recommended list - contact us for testing.