BUG: Extracted Roblox assets fail to be read due to recent versions of Roblox on Windows using zstd compression on cache.

[nerdydumbykier]

Hello! As of recently, I have been encountering errors with the extracted audio files (sounds only). Something like CRC mismatch shows up on FFmpeg and mpv when reading the audio files. I assume that this is caused by a recent Roblox update on PC that likely changed how the rbx-storage.db database is stored.

UPDATE: This issue has been caused by Roblox using zstd compression on the cache files on Windows, leading to corrupted extracted files. There are temporary workarounds:
the first is use Sober on Linux and extract files from its cache in RoExtract:
~/.var/app/org.vinegarhq.Sober/cache/sober/http
~/.var/app/org.vinegarhq.Sober/cache/sober/rbx-storage
~/.var/app/org.vinegarhq.Sober/data/sober/appData/rbx-storage.db
the second is to use a tool that grabs the cache files and checks for the zstd magic byte 28 B5 2F FD and extracts them into a folder, then let RoExtract combine the decompressed files together, or do it manually but tediously.

The main solution is to implement a function in RoExtract which decompresses the zstd compressed cache files before combining those into usable files.

No errors show up on the log. I am on the development build (2025-11-22) by the way, but still reproducible on release v1.02.

2025-12-03 04:16:09  INFO:  An update is available. [src\updater.rs:66:5]
2025-12-03 04:16:09  INFO:  RoExtract v1.02 (Minor Update) [src\updater.rs:67:5]
2025-12-03 04:16:09  INFO:  - Fixed windows defender (And other AVs) false positive
  - Remove opt-level 3 on dependencies
  - Remove symbol stripping
  - Switch LTO to thin
  - Add more file info

**Full Changelog**: https://github.com/AeEn123/RoExtract/compare/v1.0.1...v1.02 [src\updater.rs:68:5]
2025-12-03 04:16:09  INFO:  C:\Windows\Fonts\msgothic.ttc: valid [src\gui.rs:296:21]
2025-12-03 04:16:42  INFO:  username exited GUI [src\updater.rs:81:22]
2025-12-03 04:16:42  INFO:  C:\Windows\Fonts\msgothic.ttc: valid [src\gui.rs:296:21]

How to replicate issue:

1. Open Roblox and launch any game (leaving is optional).
2. Extract sounds to any folder.
3. Try to open any of the sounds extracted with any media player.
4. Error will happen (CRC mismatch or unreadable file).

Extra: I tried using the rbx-storage.db that comes from Sober (Roblox on Linux) and the extracted audio files still work just fine—no errors. However, this will likely stop working once the Roblox Android client updates.

Irrelevant, but thank you so much for creating this tool. It has been a huge help to me with extracting audio assets that would otherwise be impossible without this tool.

[AeEn123]

Can you send the full output of the error from FFMpeg and mpv?
I can't replicate this issue due to not being able to access a Windows machine right now
And are the file sizes reasonable for an audio file? Anything under 100kb is a sign that something is actually wrong for an audio file

[nerdydumbykier]

I've attached the log files with the full output since it's too long. Maybe ignore the MP3s since they're less than 1kB.
I've extracted these from Work at a Pizza Place game just to test, and this is with a fully clean Roblox cache.

List of files: (178 items, 174 OGG files)
ListOfAudiofiles.log

mpv:
mpvOutput.log

FFmpeg output samples (for demo):

E:\pizzaplace> ffprobe .\fffa8f032d083ec0d0f093bb980bc942.ogg
ffprobe version N-121186-g03c054d43c-20250923 Copyright (c) 2007-2025 the FFmpeg developers
  built with gcc 15.2.0 (crosstool-NG 1.28.0.1_403899e)
  configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --enable-shared --disable-static --disable-w32threads --enable-pthreads --enable-iconv --enable-zlib --enable-libxml2 --enable-libvmaf --enable-fontconfig --enable-libharfbuzz --enable-libfreetype --enable-libfribidi --enable-vulkan --enable-libshaderc --enable-libvorbis --disable-libxcb --disable-xlib --disable-libpulse --enable-opencl --enable-gmp --enable-lzma --enable-amf --enable-libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 --enable-libdvdread --enable-libdvdnav --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-libkvazaar --enable-libaribcaption --enable-libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-libplacebo --enable-librist --enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-libzmq --enable-lv2 --enable-libvpl --enable-openal --enable-liboapv --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --enable-vaapi --enable-libvidstab --enable-libvvenc --enable-whisper --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-libs=-lgomp --extra-ldflags=-pthread --extra-ldexeflags= --cc=x86_64-w64-mingw32-gcc --cxx=x86_64-w64-mingw32-g++ --ar=x86_64-w64-mingw32-gcc-ar --ranlib=x86_64-w64-mingw32-gcc-ranlib --nm=x86_64-w64-mingw32-gcc-nm --extra-version=20250923
  libavutil      60. 13.100 / 60. 13.100
  libavcodec     62. 15.100 / 62. 15.100
  libavformat    62.  6.100 / 62.  6.100
  libavdevice    62.  2.100 / 62.  2.100
  libavfilter    11.  9.100 / 11.  9.100
  libswscale      9.  3.100 /  9.  3.100
  libswresample   6.  2.100 /  6.  2.100
[ogg @ 00000226321ea4c0] CRC mismatch!
.\fffa8f032d083ec0d0f093bb980bc942.ogg: End of file

Notice the CRC mismatch and End of file error.

E:\pizzaplace> ffprobe .\07091372a39940bf917245c97c014d56.ogg
ffprobe version N-121186-g03c054d43c-20250923 Copyright (c) 2007-2025 the FFmpeg developers
  built with gcc 15.2.0 (crosstool-NG 1.28.0.1_403899e)
  configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --enable-shared --disable-static --disable-w32threads --enable-pthreads --enable-iconv --enable-zlib --enable-libxml2 --enable-libvmaf --enable-fontconfig --enable-libharfbuzz --enable-libfreetype --enable-libfribidi --enable-vulkan --enable-libshaderc --enable-libvorbis --disable-libxcb --disable-xlib --disable-libpulse --enable-opencl --enable-gmp --enable-lzma --enable-amf --enable-libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 --enable-libdvdread --enable-libdvdnav --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-libkvazaar --enable-libaribcaption --enable-libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-libplacebo --enable-librist --enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-libzmq --enable-lv2 --enable-libvpl --enable-openal --enable-liboapv --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --enable-vaapi --enable-libvidstab --enable-libvvenc --enable-whisper --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-libs=-lgomp --extra-ldflags=-pthread --extra-ldexeflags= --cc=x86_64-w64-mingw32-gcc --cxx=x86_64-w64-mingw32-g++ --ar=x86_64-w64-mingw32-gcc-ar --ranlib=x86_64-w64-mingw32-gcc-ranlib --nm=x86_64-w64-mingw32-gcc-nm --extra-version=20250923
  libavutil      60. 13.100 / 60. 13.100
  libavcodec     62. 15.100 / 62. 15.100
  libavformat    62.  6.100 / 62.  6.100
  libavdevice    62.  2.100 / 62.  2.100
  libavfilter    11.  9.100 / 11.  9.100
  libswscale      9.  3.100 /  9.  3.100
  libswresample   6.  2.100 /  6.  2.100
.\07091372a39940bf917245c97c014d56.ogg: End of file

This one has no CRC mismatch but has End of file error. Yet still unreadable.

Most of the audio files are below 60kB by the way.

tl;dr, none of the files are playable nor readable. I can also provide output with Sober cache if needed since they work just fine and just as small as the Windows-extracted one I have.

[nerdydumbykier]

I think I may have found the problem!
I decided to read the cached files with a hex editor, and there it was. The problem is that the cached files are first compressed in zstd, based on the text Content-Encoding: zstd and Roblox CDN links being https://xx.rbxcdn.com/$randomdata_compressed2. This does not happen on Sober because the Roblox CDN links don't link to the compressed versions of the cached data for the Android client yet, as well as no visible signs of zstd on the hex editor, which in turn the data isn't compressed and why RoExtract still works with Sober.

So what I did next is to find the magic data of zstd 28 B5 2F FD inside that cached file and remove the bytes before it in my hex editor, and save, then add a .zst extension to the file, then use zstd -d $file.zst. It gets decoded successfully!

In RoExtract, maybe it could be possible to add a function that decompresses the files compressed in zstd before extracting and piecing the files together.

[AeEn123]

Oh thanks! I should get working on that.
Honestly, I don't really have motivation for the program, so it'll take me a while to get it implemented.

If you are willing to try yourself, you can try opening a pull request and implementing the decompression yourself.
You can use a crate such as zstd to get started!
I'm not saying you have to, I will get it done eventually, but any work will be appreciated!