Merge Audio and Video in Seconds with FFmpeg

thanks, really helpful and well explained

Thank you, another question, is there a way to extract audio from a video, loseless with ffmpeg?

Very nice.... works like a charm :)

i always run `ffmpeg -i input.mkv output.mp4`
to reduce the video size for yt uploading

Can you explain this error - incorrect number of samples in encryption info
I was trying to merge video.mp4 and audio.mp4 to a MP4 output.
Somethings with the samples I don't understand.

ffmpeg -i input.mp4 -i input.mp3 -c:v copy -c:a aac -map 0:v -map 1:a output.mp4

Gimme the code!!!!!! :)