Hello all, newbie here.
Mostly with VHS and minidv captured video.
In researching, I am seeing that some are using ffmpeg to crop and resize the footage to 720x540.
What are the benefits in resizing to this versus leaving as 720x480?
My videos were captured this method & format:
VCR to minidv cam pasthrough to pc by firewire
720x480 at 29.970fps, DV (NTSC)
Thanks in advanced.
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Last edited by Dickieg10; 3rd Nov 2020 at 08:17.
An NTSC DV cap has a frame size of 720x480. If you downscale to 640x480 you lose some resolution horizontally. If you upscale to 720x540 you don't lose any resolution horizontally but you must deinterlace before scaling. And the picture might be a little blurry vertically. Both are 4:3 frame sizes, suitable for square pixel encoding.
But surely 720*540 is 'illegal'. Yes it is 4:3 and, yes, it will in all probability play fine in a PC but other playback devices ?
Surely the 'resize' should be 720*544
My videos are capture at 720x480, I corrected my original post & added some more details.
I do plan to deinterlace with QTGMC using avisynth & ffmpeg.
My commands would deinterlace, crop, resize (if needed) & convert to a different container in same pass.
Will probably use a prores codec.
Right now, I have people people who want this footage. Some on DVD, others on a streaming platform.
Just trying to understand what size would be best for long term storage.
An astounding amount of iTunes AVC video is mod4. I've even seen mod2 heights on occasion. Players don't care any more.
The only DVD format for which you need to reduce the width or resize the height, assuming you resizing to square pixel dimensions, happens to be 4:3 NTSC.
16:9 NTSC and PAL can be resized to square pixel dimensions by increasing the width. ie before cropping:
16:9 NTSC - 854x480
16:9 PAL - 1024x576
4:3 PAL - 768x576 or 786x576, depending on how you resize.
Not all players display anamorphic video correctly (my TV's media player doesn't), so I resize everything to square pixels, but if you keep the original resolution, or don't resize after cropping, and set the appropriate aspect ratio when encoding, you're not increasing the amount of video that needs to be encoded.
Ok. But I now read the addit info in the OP that the capture is 4:3 DV-AVI. Surely that displays at 640*480 and would be the more appropriate resize ?
Now if these captures were PAL I am sure that one would not recc a resize to 720*540 >> claimed loss of definition on the vertical << but resize to 768*576. You would not gain definition by increasing pixels from 720 would you ?
Note that every scaling can potentially damage the video So the fewer scaling steps the better. I usually keep the original resolution and encode with sample aspect ratio flags. Then only use devices that display that properly. But, as has been stated, some devices do not obey the AR flags -- so that's not for everybody.
Last edited by jagabo; 3rd Nov 2020 at 10:36.
You can do a similar same thing when encoding anamorphically, but if you want the same output dimensions each time you have to crop each episode the same way or prepare for some resizing anyway. My OCD is aggravated more when the dimensions are different.
A PAL DVD running full screen.
[Attachment 55723 - Click to enlarge]
A 640x480 encode running full screen.
The minor loss of fine detail is solely due to denoising/deblocking.
Whatever was lost was gone before I resized.
[Attachment 55724 - Click to enlarge]
Edit: Fixed posting the same pic twice.
Is DV interlaced? I can't remember. If not I'd probably be less enthusiastic with the downscaling.
I once had a hybrid NTSC dvd( telecined and interlaced), and for the life of me could not get it right. An IVTC in Fairuse Wizard still left severe combing and not the desired resolution and even resorting to an Xvid in the great AutoGK left a horrible green line at the bottom of the 4:3 video, despite 704x528 exact 4:3 resolution. In the end encoded it in Handbrake and the only resolution it allowed me to get an exact 4:3 was 720x544 after much testing out short samples with telecining and decomb set to auto as well. The anamorphic strict settings etc always ended up as 1:5 ratio on a 720x480 cropped. It would not allow me 704x528 which I wanted originally. 720x540 is definitely not correct I think.
720x544 or 1:32 sufficed!
Do you have an interlaced version? De-interlacing made far more of a mess than simply resizing it did.
That's not really a fair test because you can't even upscale it directly to 1440x1080 without changing it. The only way to do that is to upscale using the storage aspect ratio, not the display aspect ratio.
However, the software reading the DV signal coming in from the camera (e.g. Sony PlayMemories Home) has no way of knowing what the source is, so it just blindly puts a 4:3 tag in the AVI (actually AVIX) files that it writes. One could use FFmpeg to retag the non-Digital8 material as 15:11, or when transcoding, crop 16px and tag the resulting 704x480 as 4:3.
Is DV interlaced?
Last edited by ItaloFan; 4th Nov 2020 at 13:30. Reason: typo