VideoHelp Forum
+ Reply to Thread
Results 1 to 9 of 9
Thread
  1. Member
    Join Date
    Mar 2013
    Location
    UK
    Search PM
    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.
    Quote Quote  
  2. Member
    Join Date
    Mar 2008
    Location
    United States
    Search Comp PM
    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
    Quote Quote  
  3. 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):

    Code:
    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.
    Last edited by jagabo; 16th Mar 2019 at 19:18.
    Quote Quote  
  4. Member
    Join Date
    Mar 2013
    Location
    UK
    Search PM
    Originally Posted by davexnet View Post
    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.

    Click image for larger version

Name:	avidemux.png
Views:	136
Size:	56.9 KB
ID:	48429
    Quote Quote  
  5. Member
    Join Date
    Mar 2008
    Location
    United States
    Search Comp PM
    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
    Quote Quote  
  6. Member
    Join Date
    Mar 2013
    Location
    UK
    Search PM
    Originally Posted by davexnet View Post
    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.
    Quote Quote  
  7. 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:
    Code:
    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"
    Image Attached Files
    Last edited by Selur; 17th Mar 2019 at 16:49.
    users currently on my ignore list: deadrats, Stears555
    Quote Quote  
  8. Member
    Join Date
    Mar 2013
    Location
    UK
    Search PM
    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?
    Quote Quote  
  9. Originally Posted by PCC View Post
    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
    Quote Quote  



Similar Threads

Visit our sponsor! Try DVDFab and backup Blu-rays!