[FFmpeg-user] Transcoding 2048x480 to 1920x1080

[Sven C. Dack]

On 13/09/16 14:09, Steve Boyer wrote:
>> ffmpeg -i video2008.mp4 -i audio2008.m4a -q 1 -c:v libx264 -preset slower
>> -s 1920x1080 -map 0:v:0 -map 1:a:0 -y video+audio2008.mp4
>>
>>
> Like an adult diaper, it depends. If I'm reading it right, you're going to
> be greatly stretching out the Y-axis. Is that what you are wanting to do?
> That would really distort the image.

I was wondering the same, but now on second thought might he be trying to give 
the picture black borders, and/or to render subtitles under the picture... It 
would help to know what the purpose here is.

In general do I suggest to refrain from any kind of up-scaling unless it's meant 
to be overlayed with another source (i.e. Picture-in-Picture, hard-coded 
subtitles, ...). If the goal is to increase the resolution then it is best to 
leave it to the video player. Upscaling an image doesn't increase the amount of 
original information contained within, but inflates it. Different upscaling 
algorithms then leave different signatures of which not all are pleasing to 
everyone. Upscaling also increase the amount of processing required by the 
encoder and decoder. Unless there is a good reason for it should one leave 
upscaling/zooming to the players and displays.

Sven