Use the command ffprobe -show_packets VID_20221215_105814_430.mp4.mkv to see if there are any dropped frames or timestamp gaps, which indicate the "health" of the video stream.
Tools like MKVToolNix often wrap MP4s into MKV to edit without re-encoding.
If you have access to the file, I recommend running these tools to see the "deep features" for yourself: VID_20221215_105814_430.mp4.mkv
If this was a screen recording rather than a camera capture, you might find a variable frame rate (VFR). If it's a camera capture, it likely uses H.264 (AVC) or H.265 (HEVC) video codecs with AAC audio.
Likely a millisecond or sequence identifier used by the camera software to prevent naming collisions. If it's a camera capture, it likely uses H
A true MKV file must start with the EBML header 1A 45 DF A3 . If the file fails to play, checking this header confirms if it's a genuine MKV or just a renamed MP4. 3. Practical Deep Inspection Steps
If the original MP4 was corrupted (e.g., missing a "moov atom"), recovery software often outputs to MKV to stabilize the stream. 2. Forensic & Deep Feature Extraction If the file fails to play, checking this
MKV files can store rich metadata that MP4s cannot, such as "Writing Application" (e.g., mkvmerge v70.0.0 ) or "Writing Library" (e.g., libebml ). This reveals which software handled the file after it left the phone.