Why create a custom profile?
- You can't find the format you need in the predefined list of conversion profiles or you'd like to tweak one with a minor adjustment (specific video/audio codecs and channels + video resolution) 
- You want to convert to DVD, Blu-ray or AVCHD format with embedded subtitles (predefined profiles use soft subtitles instead)
- You want to convert to 4k resolution, (generic predefined profiles convert to the source files resolution so if your source is not 2k or 4k resolution but want to convert it to this resolution create a custom profile)
- You want special videos settings: GOP size, H264 options, Rate control, Motion estimation, limit the video bitrate etc.
- You have a video you know that plays on a specific device and you want to create a profile based on that video to insure compatibility
- Remux copy certain video or audio streams without encoding them

To create a custom profile: 

Step 1)  Click on the list of conversion profiles and select the last entry Custom profiles | Click here to add a custom profile…  
create custom profile

A new window will open which we call our "Custom profile editor".
Enter a name for your profile and select the file format.  
If you want to create a profile based on a file you already know is compatible with your device then load it by clicking on "Get profile from sample file".  Press Next.

step 1
Custom profile name: Enter a name for your new profile. The name you enter here will be displayed in the profile list under custom profiles and will be allow you to differentiate this profile from others you may create.

File format (container): Select the file format you want to create, in other words you are selecting the structure or extension the final file will have (the video codec choice is available on the next step). When selecting a format filter, only what is pertinent to this format will be displayed: further options will be available in the next steps. If you are curious to see what are the different settings available, select MKV as the file format and look at the next steps to see all the options.
However, know that all these might not be available depending on the final file type you want to create in order to comply with the standards defined by that format.

Get profile from sample file (button): This is particularly useful if you have a video file you know already plays on the device you want to convert files for, you can transfer it to your computer and load it in the custom profile editor so that a custom profile will be created based the specs of this file. Clicking on this button opens a browser window for you to load a video file. Once the parameters of that file have been loaded, a dialogue will appear: "Encoder profile successfully imported".
That is not all, you must click on "Next" all the way until Step 5 and save your profile. If you entered a custom profile name or a file format above, it was probably updated with to reflect the specs of the file you loaded - best leave those alone but you can overwrite the values if you change those now.

Output folder: If you want all your conversions with this profile to be stored in a specific location, check the box and click on the three dots to provide a path file that will be used.

Step 2) Adjust the video settings and click on Next.
If you need more information on each setting, click on the software and hover your mouse and item and wait a second for the hint to appear (a text: see the example below). If you do not want the video stream to be reencoded, check the option:
[ ] Copy (remux) if possible, otherwise use:
If you want to use a specific video resolution select it in the list and select the last item in the drop down list "Custom resolution" and enter those values.  
example of hint

Step 3)  Adjust the video settings and click on Next
If you do not want the audio stream to be reencoded check the option:
[ ] Copy (remux) if possible, otherwise use:
step 3

Step 4)  
Adjust the video settings and click on Next
If you do not want the subtitle stream to be reencoded check the option:
[ ] Copy (remux) if possible, otherwise use:
- Embed in the video - means the subtitles will be hardcoded into the video, this give a very nice result for subtitles, you can only have one subtitle stream if you select this option.
- DVD Subtitles - are subtitles that can be activated or deactivated as you watch the video via the menu or the remote control by pressing the "Subtitles" button.  Supports many subtitle streams.
- Blu-ray Subtitles - like DVD subtitles can be activated or not (see description above).

Step 5) 
It presents a recap of most of the settings edited. Press Save and close. The profile editor will close and the profile you just made will be selected. If you haven't already, load the files you want to convert and press "Start" for the conversion to begin.  

step 5