The export needs an intentional end policy
When separate media tracks have different lengths, the output workflow must decide when to finish. FFmpeg's shortest option ends encoding when the shortest output stream ends. If that behaviour is selected unintentionally, a shorter soundtrack can truncate a longer picture. The missing ending is not automatically a decoder fault or an interrupted upload.
Keep the original inputs and the exact export settings. Identify the intended programme length and the length of each selected track. A video preview running to the end before export does not prove that the export's end policy will preserve that full duration. The final file must be checked independently.
A hypothetical demonstration with music
Suppose a creator owns a ten-minute demonstration and has permission to use a three-minute music bed. An export configured to finish with the shortest stream may end around the music's boundary. The useful comparison is the completed output duration against the input lengths and selected policy. Re-exporting the same command under another filename would preserve the same decision.
Decide what the audience should hear after the music ends. The answer might be the demonstration's speech alone, an approved continuation of music or silence. Those are editorial choices with different processing requirements. Do not loop a track merely to make a number match without checking the permitted use and how the repetition sounds.
Inspect every selected stream
A sparse subtitle or another selected stream can also affect a shortest-stream workflow, and FFmpeg documents buffering considerations for sparse streams. Review the actual output stream selection rather than assuming only video and background music are present. A copied preset may carry options that were appropriate for another task but wrong for this one.
Change the relevant end policy through the documented tool or editor workflow and preserve the rest of the baseline. Do not combine the correction with unrelated resolution, loudness and caption changes unless they are required. One understandable adjustment makes it easier to establish why the missing ending returned.
Verify the end content, not only the duration label
Open the completed file and inspect the final scene and final intended sound. A duration near ten minutes is useful but does not prove that the final content is correct or that a track was not padded unexpectedly. Check transitions where the shorter audio ends and confirm that speech remains aligned.
Test the deliverable in its intended destination and retain the export note with the project. A later upload failure is a separate stage from local truncation. The useful outcome is an authorised programme with an intentional ending and a documented track policy, rather than assuming that a successful export always runs as long as its longest source.
Questions answered
Why might a ten-minute video export end with a three-minute soundtrack?
A shortest-stream output policy can use the shorter selected stream as the ending condition. Inspect the actual export settings and tracks.
Should I automatically loop the music?
No. Choose the intended ending and confirm permitted use. Continuing music, retaining speech alone and silence are different editorial outcomes.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.