> For the complete documentation index, see [llms.txt](https://wiki.redmodding.org/cyberpunk-2077-modding/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.redmodding.org/cyberpunk-2077-modding/for-mod-creators-theory/files-and-what-they-do/file-formats/videos-.bk2.md).
# Videos: .bk2
Editing and Replacing videos in CyberPunk 2077 with RAD Video Tools
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.
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`)
Visit Viktor's RipperDoc, the boxing video consistently plays on his screen for easy testing.
[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
### Give it a Play
Converting to MP4 file format
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
1. Convert
2. Defaults to MP4, keep it.
### Video Specifications:
**Length:** Should match **the converted .mp4**
**Export:** MP4
**Size:** 480p
**FPS:** 15fps is the game speed, 30fps is possible, but not recommended.
**You must export to Bink 2.**
## 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.
[HxD](https://mh-nexus.de/en/hxd/) is a good windows solution that is free.
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.
[Discord](https://discord.gg/redmodding) community.
### Python Script: 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.
{% 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
---
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