While "21524" is not a universal MP4 error or codec code, it is frequently found in the following contexts:
Where did you (e.g., an error log, a camera folder, or a download)?
Open the file in VLC Media Player and press Ctrl+J to view technical specs.
💡 Ensure you are using the most recent version of your playback software, as the ISO/IEC 14496-14 standard for MP4 is updated periodically (latest major revision in 2020). To provide a more specific report, could you tell me:
Run the command ffmpeg -i 21524.mp4 to see a detailed stream analysis.
Are you trying to or just identify its content ? What software are you currently using to interact with it? ISO/IEC 14496-14:2020 - Coding of audio-visual objects