How to change mp4 aspect ratio to 16:9 using ffmpeg?
<p>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!</p>

<p>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 ?</p>

<p>I got two types of source with following information:</p>

<pre><code>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)
</code></pre>

<p>ffmpeg code used to trim the original video:</p>

<pre><code>   ffmpeg -i orginalVideo.mp4 -ss 00:25:55 -t 00:04:02 -acodec copy -vcodec copy videoForYoutube.mp4
</code></pre>