When I walk through the system folders of my old Android phone to clean it, I could see that there was a mtklog folder containing an audio_dump folder, itself containing many files in the form VMLog_%Y_%m_%d.vm in the Internal Storage folder.

As the name of the folder suggests that I have to make audio files, I tried to play them as a PCM RAW file, without success. Despite several searches on the file format, I did not find any information.

Someone knows what these files are, if it is possible to read them to know what they are, or just if there is a risk to delete them because I would not like to make the system unstable by deleting them?

  • Deleting something from Internal Storage (/sdcard) won't make system unstable. Stock apps are habitual creating such type of junk. But if you are curious, you can try strings on those files to take an idea what they contain. Or you can watch the directory to track which and when an app/process writes those files. Mar 28, 2019 at 22:34
  • Thank you very much for your time and your clear answer. What's is 'Stock apps' please ? I have use strings program with different encoding on .vm file but the files are binary file without usefull strings informations. I have also try 'hexdump' and the only usefull informations is two bytes (probably more) repeated in the file and other bytes also repeated in the files. But with this 'MAGIC header value' I have no found any result on search motors.
    – mizizad
    Mar 29, 2019 at 5:56
  • Stock apps are those shipped with original ROM (OS) by OEM. Usually there are a lot of bloatware among them. If strings and hexdump don't work, you can watch the directory to find out the culprit process. Mar 29, 2019 at 6:47

1 Answer 1


A MediaTek SoC based Android phones usually ships with a lot of "MediaTek Apps" that much of the apps has logging turned on by default. Logging is used to debug or in layman's terms "Identify bugs, problem or issues easily" so that it would be ready for production use or "normal user's daily driver".

They didn't turn off logging when the phone ships because maybe they are plain lazy or they "forgot". It has been over a decade that MediaTek phones has this "mtklog" folder.

You can safely delete this folder as it has no use at all for a normal user. It doesn't affect anything in the phone's ecosystem and this option is supposed to only be used in factory or the manufacturer and deleted before a device is sold to normal users.

Technical Information (Advanced users only):

I have seen this folder everywhere when I use a MediaTek device. It takes up a lot of space because I think the logging level is set to "Debug" mode. It usually takes up to 70MB and it is basically useless unless you want to fix an app or the system's services or you want to study the MediaTek environment. Nothing is inside the "mtklog" folder besides "every single move that has been captured" and saved to a log file of an app or service. It might introduce vulberabilities if personal information are logged.

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