How to change mp4 aspect ratio to 16:9 using ffmpeg?

Question

I got an mp4 video that I copy 4 minute of it using ffmpeg. After uploading to YouTube I noticed the uploaded video has black bars on both side of video(right and left side)!After searching for a way to remove those black bars I found that I need to use yt:stretch=16:9!However,using yt:stretch=16.9 tag will not remove the black bars on iPhone and Samsung smart tv YouTube app!

could an expert help me change the aspect ratio of original mp4 video to 16:9 using ffmpeg (without losing video quality) for re uploading to YouTube? Thanks in advance ?

I got two types of source with following information:

1)Resolution:720x576 ,Frame rate:25 . Codec:H264 - MPEG-4 AVC(part 10)(avc1),
2)Resolution:848x480 , Frame rate:24.804393,Codec:H264 - MPEG-4 AVC(part 10)(avc1)

ffmpeg code used to trim the original video:

   ffmpeg -i orginalVideo.mp4 -ss 00:25:55 -t 00:04:02 -acodec copy -vcodec copy videoForYoutube.mp4

Answer 1

Unfortunately none of the provided answers seemed to do the trick for me with MKV file and FFMpeg 5.1.2.

I found this simple command after some diving that does the trick converting video to 16:9 aspect ratio:

ffmpeg -i input.mkv -c copy -aspect 16/9 output.mkv

Answer 2

This command is also useful

ffmpeg -i input.mp4 -crf=20 -vf 'split[original][copy];[copy]scale=ih*16/9:-1,crop=h=iw*9/16,gblur=sigma=80,eq=saturation=0.9[background];[background][original]overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2' output.mp4

this command unlike Gyan command expends the size of the video without stretching it and it takes more time to convert but Gyan command is faster.

source

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Has been tested using ffmpeg version 3.4.8-0ubuntu0.2 on linux

Answer 3

Assuming the video looks acceptable after stretching, you can use the following command:

ffmpeg -ss 25:55 -t 4:02 -i input.mp4 -vf scale=ih*16/9:ih,scale=iw:-2,setsar=1 -crf 20 -c:a copy YT.mp4