Is it possible to change the number of pixels without reencoding?

[shampistols69]

I know that it is possible to change the duration of a video without reencoding. https://www.youtube.com/watch?v=oT1xIYC2f3U
Say I have a DVD video I want to upload for YouTube in good quality. Can I change the pixel information from e.g. 720x576 to 1440x1080 without reencoding at all?

[Cornucopia]

For local playback it is possible with certain codecs & containers, to have a crop setting (downward) where for example you start with a 720x480 and display only 704x360, but there is NO way to resize up without re-encoding (other than runtime playback window expansion).
But upsizing doesn't give you any new detail anyway, so there are few reasons to do it (other than the well-known YT HD/SD threshold, or compilation editing with other HD material).

Scott

[usually_quiet]

No. You must re-encode to increase a video's resolution. (A video's resolution is the video's width by height in pixels.)

... but Scott's explanation is better.

[shampistols69]

upsizing doesn't give you any new detail anyway, so there are few reasons to do it (other than the well-known YT HD/SD threshold, or compilation editing with other HD material).

Scott

Thanks. Just thought it was worth an ask. HD/SD threshold on YouTube is the only reason I upsize anyway.

[jagabo]

I don't know what Youtube will do with it but it's possible to lie about the frame size in the MPEG headers. Try DVDPatcher.

[shampistols69]

I don't know what Youtube will do with it but it's possible to lie about the frame size in the MPEG headers. Try DVDPatcher.

Oh my goodness! It works to change the pixel info too! On windows properties, it shows that I changed it to 1350x1080 pixels. On MediaInfo it still says 720x576. I made a test post on YouTube and it works! This is awesome. Won't have to spend time re-encoding anymore. https://youtu.be/P-fukf3k7r0

[shampistols69]

If I changed the pixels to 4k, I could upload basically a totally identical video with a much smaller file size.

[johns0]

Nope.

[Alwyn]

Well I'll be blowed! I patched the "first header only" ie not "entire file", of a 720x576 MPEG 2 file to 1920x1440 and YT encoded it HD in VP9. Impressive.

I did try the "entire file" option too but got a grey box covering most of the YT screen.

I'm not sure how good YT's upscaling is though.

[dellsam34]

Oh my goodness! It works to change the pixel info too! On windows properties, it shows that I changed it to 1350x1080 pixels. On MediaInfo it still says 720x576. I made a test post on YouTube and it works! This is awesome. Won't have to spend time re-encoding anymore. https://youtu.be/P-fukf3k7r0

Youtube will just upscale your video to 1440x1080 (not sure where you come up with 1350x1080), Would you trust YT de-interlacing and upscaling, also compression is not that great. That's the reason I de-interlace and upscale at 10fps, takes time but worth it.

[shampistols69]

1350x1080 because when I tried 1440, the playback stretched my video wider than the 4:3 ratio. I'd rather let YouTube take care of upscaling and re-encoding than to re-encode twice, but frankly that's just an opinion. The only major con IMO about using DVDPatcher is that I can't use the Yadifx2 filter, that's not the program's fault.

[Cornucopia]

1440x1080 at 1:1 PAR *IS* 4:3 DAR, so something else must be odd about your material.

Scott

[shampistols69]

The pixels of my DVD PAL are 5:4. It displays as 4:3 despite the pixels. Therefore, when I increase the pixel number, I have to keep 5:4. It does display as 4:3 on playback. I've tried this with multiple PAL DVD videos.

[lollo]

when I increase the pixel number, I have to keep 5:4

Not really.

When you upscale your 720x576 frame you start from a SAR (Sample Aspect Ratio) = 5/4, a DAR (Display Aspect Ratio) = 4:3 and then a PAR = 16/15 (PAR = DAR / SAR)

If upscaling to 1080 heigth, 1080/3*4=1440, so frame size is 1440x1080.

You have finally SAR=4/3, DAR=4/3 and PAR=1, as Cornucopia properly said.

[jagabo]

Note that shampistols69 is not resizing, he's lying to youtube about the frame size of his uploaded video. It may be that youtube is using the original sampling aspect ratio (implied 16:15) when it scales. That would make a fake 1350x1080 the correct size -- adding a 16:15 SAR to that will result in a 1440x1080 square pixel upscaled size.

[lollo]

Yes, correct for YT processing, but shampistols69 said "I've tried this with multiple PAL DVD videos", hence my doubt. It's probably a misunderstanding...

[Alwyn]

My test video in post #9 (1920x1440) was set to 4:3 in DVDPatcher and it displayed correctly as 4:3 on Youtube. I just tested 720x576 4:3 patched to 1440x1080 4:3 and it displays correctly in YT.

VLC Player also displays it correctly as 4:3.

1350x1080 because when I tried 1440, the playback stretched my video wider than the 4:3 ratio.

What program stretched your video?

[shampistols69]

VLC Player also displays it correctly as 4:3.

1350x1080 because when I tried 1440, the playback stretched my video wider than the 4:3 ratio.

What program stretched your video?

MPC-BE. I tried what you did and played the video with VLC. It shows the correct ratio on VLC, but not the program I was using. I did some other tests. The horizontal size actually does not matter for uploading to YouTube or viewing on VLC. The correct ratio will be shown on VLC and YouTube regardless of the horizontal size. Might as well keep it the same.

[shampistols69]

I'm trying to find a way now to do this with MP4 videos. Maybe it can be done with a hex editor, but learning it seems mildly difficult.

[lollo]

The correct ratio will be shown on VLC and YouTube regardless of the horizontal size

VLC acts according to what you set in Video -> Aspect Ratio.

If you specify "Default" it will read the DAR in the file and display accordingly. If the DAR is not specified in the file (i.e. for avi video), the SAR is used (which often is different than DAR, giving wrong proportion)

If you specify "4:3" it will display as such.

[shampistols69]

It turns out that for MKV containers it's best to use e.g. 1350x1080 pixels or else it will stretch on YouTube.

[shampistols69]

Just remux to MKV and use MKVmergeGUI to change the header https://youtu.be/HaYOTAz4ew0

[shampistols69]

That method won't translate on YouTube though. Maybe other settings in the GUI have to be tweaked.