With Chromecast Ultra, you can stream 4K Ultra HD streams and HDR content when provided with a suitable broadband connection. For those people who wish to stream local 4K video to Chromecast Ultra, Plex Media Server can be your best choice. The bad news is that Chromecast Ultra only support to direct play 4K MP4 file format encoded with H.264 High Profile codec. If you happen to have some 4K MKV files encoded with H.265 codec, you will fail to stream the MKV file to Chromecast Ultra via Plex.
Transcode unsupported 4K H.265 MKV with Plex
Although Plex can perform the format or codec transcoding process for you, however, it is well known that 4K transcoding is very processor intensive, you will need a very powerful computer. The codec transcoding process will largely slow down your computer performance.
Convert 4K H.265 MKV with third-party video conversion app
To avoid above listed issues, you can perform the format or codec transcoding process with a third-party conversion app. Here, a powerful yet simple to use application called Pavtube Video Converter is highly recommended to you. The program has perfect importing support for all 4K/2K/HD/SD MKV files encoded with various different compression codec including MPEG-1, MPEG-2, WMV/VC-1, H.264, H.265, MVC, etc. You can easily convert unsupported MKV to Chromecast Ultra compatible 4K MP4 H.264 High Profile format with perfect quality and super fast conversion speed. The batch conversion mode allows you to load multiple MKV files at one time for conversion at one time to save your precious time.
Tips: Our program supports hard-ware encoding acceleration. You can get up to 6x faster H.264 codec encoding speed as long as you run your computer on Graphic card that supports Nvidia CUDA or AMD App technology.
For Mac users, please download Pavtube Video Converter for Mac to perform MKV to Chromecast Ultra conversion process on macOS High Sierra, macOS Sierra, Mac OS X El Capitan, Mac OS X Yosemite, Mac OS X Mavericks, etc.
Step by Step to Convert Unsupported MKV for Chromecast Streaming via Plex
Step 1: Load unsupported MKV files.
Download the free trial version of the program. Launch it on your computer. Click “File” menu and select “Add Video/Audio” or click the “Add Video” button on the top tool bar to import unsupported MKV files into the program.
Step 2:Define the output format.
Clicking the Format bar, from its drop-down list, select Chromecast Ultra supported 4K file formats “H.264 High Profile Video(*.mp4)” under “Common Video” main category.
Step 3: Enable GPU Encode Acceleration.
Click “Tools” > “Options”, in the opened “Options” window, click “Acceleration” menu, then check “Enable GPU Encode Acceleration” otpion so that the program will accelerate converion speed when encoding video to H.264 codec.
Step 4: Begin the conversion process.
After all setting is completed, hit the “Convert” button at the right bottom of the main interface to begin the conversion process from MKV to Chromecast Ultra supported 4K format transcoding process.
When the conversion is finished, click “Open Output Folder” icon on the main interface to open the folder with generated files. Then feel free to add converted files to Plex Media Server for streaming to Chromecast Ultra.