748 - Aspect ratio output mp4 file

Dan203

Senior Developer
Staff member
And what the bug described in posts #16 and #17. Will be fixed?
It wont. H.264 video stores the aspect in a NAL attached to each video frame. We do not have the ability to edit NALs in VideoReDo. So when you save an H.264 file with the aspect changed the aspect is only applied to the NALs if you do a full recode. For MP4 we do set the MP4 header to the selected aspect, which is what you're seeing in MediaInfo. The video header "original aspect" is still 4:3, but the container has been set to 16:9. If you were to save to a container that doesn't support aspect at all, like TS, then it would not change at all. You could set to 16:9 and the output would still be 4:3 unless you did a full recode.
 

jirim100

New member
Today I found the following weird behavior:

- When I fully reencode pure 16:9 mpg file to mp4 file and in profile is Aspect ratio: No change then in player MPC-HC is in properties showed "Video: MPEG4 Video (H264) 720x576 (16:9) 25fps 2519kbps [Video]".
fully_reencode_aspect_no_change.png

- When I fully reencode pure 16:9 mpg file to mp4 file and in profile is additionally set Aspect ratio: 16:9 then in player MPC-HC is in properties showed "Video: MPEG4 Video (H264) 720x576 (71:40) 25fps 2519kbps [Video]". Why is not 16.9? 16/9 = 1.777777... but 71/40 = 1.775.
fully_reencode_plus_aspect_16_9.png
 

Dan203

Senior Developer
Staff member
Are you using the latest beta? We made some changes to how the aspects are calculated in the latest beta because there was a rounding issue like this in previous versions.
 

jirim100

New member
Yes, I am using the latest version 5.3.4.748. I can upload sample of video if you want.
 
Last edited:

Dan203

Senior Developer
Staff member
This could be a problem with the MP4 header. I made the change I was referring to in the code that controls the transcode, but I don't think I made the same change in the MP4 muxer. I'll look at it tomorrow. If I need a sample I'll let you know.
 

JMRDV

Member
I've had superior experiences with the VRD crew, back a few years ago I was more involved and together we solved a whole bunch of problems. I probably irritated them no end with my lack of technical knowledge but they kept at it time and time again. I've seen that same dedication over the years. This is an excellent program backed up by wonderfully responsive and highly adept people.
As an aside - I've interacted with a lot of small and major companies over the last few decades and cannot think of any that were better at what they do then these guys.

John
 

jirim100

New member
The following problem still occurs - is the same - in version 757d.


- When I fully reencode pure 16:9 mpg file to mp4 file and in profile is additionally set Aspect ratio: 16:9 then in player MPC-HC is in properties showed "Video: MPEG4 Video (H264) 720x576 (71:40) 25fps 2519kbps [Video]". Why is not 16.9? 16/9 = 1.777777... but 71/40 = 1.775.
View attachment 2203
 
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