# Videos: .bk2

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2Fpu61AfzNqOuzvVyWivsd%2Fimage.png?alt=media&#x26;token=9d129920-3021-4344-91f2-5feadbfd1742" alt="Viktor in his shop watching a modified video edit" width="563"><figcaption></figcaption></figure>

This wiki page is about the .bk2 file format used in the game, and how to edit them.

## TL;DR

The .bk2 file format is used in many games including Cyberpunk 2077. It stands for [Bink 2 By Rad Tools ](https://www.radgametools.com/bnkmain.htm)and needs to be used to extract and recompress the video that you want to replace.&#x20;

Converting to back to .bk2 requires a [byte offset](#byte-offset-requirement) for the video to appear in the game.

## Prerequisites

* WolvenKit (obviously)
* RAD Video Tools (available [here](https://www.radgametools.com/bnkdown.htm))
* Video Editor of Choice

## Selecting A Video File

[Searching in the asset browser](https://wiki.redmodding.org/wolvenkit/wolvenkit-app/usage/wolvenkit-search-finding-files) for .bk2 files will get you every video in the game. For this tutorial we will be using the boxing video (`q001_boxinggame.bk2`)&#x20;

Visit Viktor's RipperDoc, the boxing video consistently plays on his screen for easy testing.&#x20;

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2FwCfQnIkhpDKc84Win7vT%2Fimage.png?alt=media&#x26;token=49de687f-59d6-4a8d-8825-d1599cf3eef8" alt="asset browser"><figcaption></figcaption></figure>

[Add](https://wiki.redmodding.org/wolvenkit/wolvenkit-app/editor/asset-browser#adding-files-to-projects) `q001_boxinggame.bk2` to your project

### Locating Video File on Your Computer

Click: Open In Windows Explorer   &#x20;

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2F9risifST2QxdvbccS4W7%2Fimage.png?alt=media&#x26;token=4adc05ef-ec27-4c12-9c09-09d0d8b954e2" alt="project file selection"><figcaption></figcaption></figure>

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2FrmOaENXjhWQ8Tu0q0479%2Fimage.png?alt=media&#x26;token=8a7bc0c5-5226-4932-91e0-6cf85f8f69dd" alt="windows explorer"><figcaption></figcaption></figure>

### Give it a Play

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2F85vXOXaHprmS1ALJMTss%2Fimage.png?alt=media&#x26;token=7868ed54-1ad1-402c-b0a5-8284189bd5d2" alt="preview video" width="365"><figcaption></figcaption></figure>

Converting to MP4 file format

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2F2dTVT6a6Ok7k28ZeJkIW%2Fimage.png?alt=media&#x26;token=a50f509e-c0ac-4d83-8109-687dc09807a6" alt="RAD Tools"><figcaption></figcaption></figure>

1. Open RAD Video Editor and browse to: `\source\archive\base\movies\fluff`
2. Select File
3. Convert

**Note**: you can batch convert files in both directions by selecting multiple files.

### Output Options

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2Fhu6rJ317RsJSRc67AVJN%2Fimage.png?alt=media&#x26;token=8f97692f-7a8f-4d9e-a778-1bc9f99ddc53" alt="RAD Tools"><figcaption></figcaption></figure>

1. Convert&#x20;
2. Defaults to MP4, keep it.

### <mark style="color:$warning;">Video Specifications:</mark>

**Length:** Should match **the converted .mp4**

**Export:** MP4

**Size:** 480p

**FPS:** 15fps is the game speed, 30fps is possible, but not recommended.&#x20;

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2FZayz3pPsCFY4GbIa5GgT%2Fimage.png?alt=media&#x26;token=4130582c-1e5b-4041-976e-39a604988db9" alt="RAD Tools"><figcaption></figcaption></figure>

<figure><img src="https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2FT78EXaNOJT8HHb8kNZqC%2Fimage.png?alt=media&#x26;token=e7ead28b-da19-44ec-961d-3e3c0154cfd2" alt="RAD Tools"><figcaption></figcaption></figure>

<mark style="color:$danger;">**You must export to Bink 2.**</mark>

## Byte Offset Requirement

For reasons unknown, CyberPunk requires the **4th byte** of your .bk2 file to to be changed to: `6A`

Once your bk2 file has been created, you will need to edit the file with a hex editor.&#x20;

[HxD](https://mh-nexus.de/en/hxd/) is a good windows solution that is free. <br>

![hxd byte offset](https://1427525421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4gzcGtLrr90pVjAWVdTc%2Fuploads%2FwPOMErCdk7yPZHNWEVwl%2Fimage.png?alt=media\&token=c3664f50-a4ea-48f7-a910-0d53e6ae596c)

Change the 4th byte to 6A and save to: `source\archive\base\movies\fluff`

### [Install Your Mod](https://wiki.redmodding.org/wolvenkit/wolvenkit-app/menu/toolbar#install-mod)

Since the working directory is Archive, there is no need to import.

### Resources:

[YouTube Video](https://www.youtube.com/watch?v=FUtSw5VsNzI) for more on RAD Tools.&#x20;

[Discord](https://discord.gg/redmodding) community.

### <mark style="color:green;">Python Script</mark>: Automate byte offset all .bk2 files

This will automatically change the byte offset in all your .bk2 files at once in the working directory and subdirs. <br>

{% code expandable="true" %}

```python
import os
import glob

def modify_fourth_byte(file_path):
    """
    Opens a file in read/write binary mode and overwrites 
    the 4th byte (index 3) with 0x6A.
    """
    try:
        # Print the filename as processing begins
        print(f"Working on: '{file_path}'...", end=" ", flush=True)

        # Check file size before opening
        file_size = os.path.getsize(file_path)
        
        if file_size < 4:
            print(f"\nSkipping: File is only {file_size} bytes (needs at least 4).")
            return

        with open(file_path, "r+b") as f:
            # Navigate to 4th byte (index 3) and overwrite
            f.seek(3)
            f.write(bytes([0x6A]))
            
        print("Done (4th byte set to 0x6A).")
        
    except PermissionError:
        print(f"\nError: Permission denied for '{file_path}'.")
    except Exception as e:
        print(f"\nAn unexpected error occurred with '{file_path}': {e}")

def main():
    # Use recursive glob pattern to find files in all subdirectories
    # '**/*.bk2' tells glob to look in current and all sub-folders
    bk2_files = glob.glob("**/*.bk2", recursive=True)

    if not bk2_files:
        print("No .bk2 files found in the current directory or subdirectories.")
        return

    print(f"Found {len(bk2_files)} file(s) across all directories. Starting processing...")

    for file_path in bk2_files:
        modify_fourth_byte(file_path)

    print("-" * 30)
    print("Batch processing complete.")

if __name__ == "__main__":
    main()
```

{% endcode %}

**Authors note**: Thank you to `Dark Fortune Teller on` [Discord](https://discord.gg/redmodding) for doing the hard work finding about the Byte offset&#x20;