Videoview Does Not Play Audio In Video Properly

I have an *.mp4 file which is duration of 2 min. Now it has audio track starting from 30 seconds upto 1.10 min. The rest before 30s and after 1.10min is blank. Now the problem is w

Solution 1:

Ok finally I solved the problem by adding just 1 option -async

ffmpeg -y -i a.mp4 -itsoffset 00:00:30 sng.m4a -map0:0 -map1:0 -c:v copy -preset ultrafast -async 1 out.mp4

By default audio/video timestamps are stretched to match each other; which was my problem of audio starting from intial even after giving itsoffset.

As per Ffmpeg Doc using async 1 corrects the initial timestamp of audio only. I know that this option is deprecated; but anyhow it solved my case.

Solution 2:

There must be a simpler way to do it but the following works just fine for me:

ffmpeg -y -i a.mp4 -itsoffset 00:00:30 sng.m4a -f lavfi -i "aevalsrc=0" -filter_complex "[1:a][2:a]amix=inputs=2:duration=first:dropout_transition=0, apad[out]" -map0:v -map'[out]' -c:v copy -preset ultrafast -shortest out.mp4

It does the following:

• Create a silent sound
• Mix it with the shifted audio until the end of your m4a file
• Pad with silence indefinitely
• Map this and the input video
• Select the shortest duration (the video duration as the audio duration is infinite because of the pad filter)

Give it a try ;)

Edit: Jay's solution, using "-async 1", is a lot easier, check it!