Allow processing of videos in MKV containers (DeepLabCut#2701)

Co-authored-by: Mackenzie Mathis <[email protected]>

deeplabcut/gui/dlc_params.py

@@ -13,6 +13,7 @@ class DLCParams:
         "",
         "avi",
         "mp4",
+        "mkv",
         "mov",
     ]
 

docs/beginner-guides/beginners-guide.md

@@ -120,7 +120,7 @@ When you first launch the GUI, you'll find three primary main options:
    - First, click on **`Browse Videos`** button on the right side of the window, to search for the video contents.
    - Once the media selection tool opens, navigate and select the folder with your videos.
 
-     > **💡 Tip:** DeepLabCut supports **`.mp4`**, **`.avi`**, and **`.mov`** files.
+     > **💡 Tip:** DeepLabCut supports **`.mp4`**, **`.avi`**, **`.mkv`** and **`.mov`** files.
    - A list will be created with all the videos inside this folder.
    - Unselect the videos you wish to remove from the project.
 

docs/beginner-guides/video-analysis.md

@@ -8,7 +8,7 @@ After training and evaluating your model, the next step is to apply it to your v
 
 1. **Navigate to the 'Analyze Videos' Tab:** Begin applying your trained model to video data here.
 2. **Select Your Video Format and Files:**
-  - **Choose Video Format:** Pick the format of your video (`.mp4`, `.avi`, or `.mov`). 
+  - **Choose Video Format:** Pick the format of your video (`.mp4`, `.avi`, `.mkv`, or `.mov`).
   - **Select Videos:** Click **`Select Videos`** to find and open your video file.
 3. **Start Analysis:** Click **`Analyze`**. The analysis time depends on video length and resolution. Track progress in the terminal or Anaconda prompt.