Using MyMP4Box to change resolution

[PCC]

I've got a set of videos I need to change from 1050x576 to 1024x576.

I think it's possible with MP4Box, going by this: https://superuser.com/questions/907933/correct-aspect-ratio-without-re-encoding-video-file

But is it possible in MyMP4Box? I've selected 16:9 as the aspect ratio, but it keeps the resolution the same and squashes the image.

I couldn't get the hang of MP4Box so I tried MyMP4Box instead.

[davexnet]

I don't know about MP4Box, but it should work in Avidemux.
Load the file, choose "output format" mp4 muxer
Configure/force aspect ratio/16:9

[jagabo]

MP4Box cannot change the video resolution. But it can set flags in the video stream that tell a player how to display the video. Not all players will follow the flags.

What you're setting is the pixel aspect ratio, not the display aspect ratio. Since your video is slightly too wide to create a 16:9 image the pixels must be made slightly narrower than they are tall. By a ratio of 1024:1050. This should work (assuming the video is stream 1 and currently square pixel):

mp4box -par 1=1024:1050 filename.mp4

On the other hand, maybe your videos are the correct aspect ratio already. If they are ITU captures from analog tape they have about 9 pixels of black padding at the left and right edges. If the video includes those black pillarbox bars 1050x576 is the correct square pixel aspect ratio.

[PCC]

I don't know about MP4Box, but it should work in Avidemux.
Load the file, choose "output format" mp4 muxer
Configure/force aspect ratio/16:9

This worked for playback in VLC, but it hasn't actually changed the resolution.

I tried using the resize filter and it worked I think.

The bitrate is lower than the original file. Is there a way to make it lossless? The videos were rendered from Premiere using H.264.

[davexnet]

The reason why only flagging the file was inferred was because you mentioned mp4box, that's what that does..

To encode the file with better quality and still to have it play back on all devices, set the video output to AVC (x264)
Hit configure. On the General tab deselect "use advanced config" set preset to medium and profle to main or high
Set quality to 18 and do a test encode. Adjust as necessary - as the quality number is lowered, the bitrate
becomes higher

[PCC]

The reason why only flagging the file was inferred was because you mentioned mp4box, that's what that does..

To encode the file with better quality and still to have it play back on all devices, set the video output to AVC (x264)
Hit configure. On the General tab deselect "use advanced config" set preset to medium and profle to main or high
Set quality to 18 and do a test encode. Adjust as necessary - as the quality number is lowered, the bitrate
becomes higher

Thanks, that's worked perfectly.

Do you know how thumbnails are determined? Is it by Avidemux or Windows?

The series of videos has the same opening titles and my original files all have the same frame as their thumbnails. But one of the new ones has a different frame, so I'm wondering if something has gone wrong.

[Selur]

Do you know how thumbnails are determined? Is it by Avidemux or Windows?

Windows. Depending on the container used you could add a cover art, which Windows should use.
Attached an example mp4 file where I added a cover art.
Here's the MP4Box command line which created the attached file:

MP4Box -add "E:\Temp\22_46_43_1110_02.m4v"#video:fps=25 -add "E:\Temp\iId_1_aid_0_22_46_43_1110_01.mp3"#audio:lang=und -itags name="Der Untergang (2004)":genre="Biography, Drama, History":cover="C:\Users\Selur\Desktop\Untergang.jpg":tool="Hybrid 2019.03.16.1" -tmp "E:\Temp" -new "E:\Output\22_46_43_1110__03.mp4"

[PCC]

Thanks.

Do you know how cropping works in Avidemux?

I want to crop two pixels out, one from the left and right sides, but choosing 1 doesn't do anything. It looks like it has to be 2 to work?

[poisondeathray]

Do you know how cropping works in Avidemux?

I want to crop two pixels out, one from the left and right sides, but choosing 1 doesn't do anything. It looks like it has to be 2 to work?

It has to do with the video's chroma subsampling.
https://en.wikipedia.org/wiki/Chroma_subsampling

If it's YUV 4:2:0, you cannot crop by 1. The dimensions have to be evenly divisible by 2.

If it's RGB , or YUV 4:4:4, you can crop by 1