Could you tell me or what software you were using when it appeared? This will help me give you a much more specific answer.
Based on common file naming patterns, here are the most likely explanations for what you are seeing: _m_smp4
: Use a tool like MediaInfo or VLC Media Player to "Open" the file; these can often read the internal header to tell you the true codec, even if the file extension is non-standard. Could you tell me or what software you
: If this appeared after using a specific downloader or editing tool, check that software's "Export" or "Save" settings to see if the process was interrupted. : If this appeared after using a specific
: Files starting with an underscore or period are often treated as hidden or system-specific files. If you found this in a system folder, it is likely a pointer or index file for a video gallery. How to handle this file:
: Many mobile apps (like WhatsApp, Instagram, or TikTok) and video editors use underscores and specific codes to denote temporary cache files or fragmented MP4 parts during an upload or download process. The m often stands for "mobile" or "media," and smp4 is likely a shorthand for "segmented MP4."