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Converting 16:9 to 4:3 while keeping quality

andymartin
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I'm kinda new at video editing so this may be an easy fix or impossible. I have footage shot in 720p 16:9. I want to convert it to 1.33 (4:3) without loosing quality so I can combine it with footage shot natively in 4:3. The completed project will be shown on a video projector that is also native 4:3. Should I use pan and zoom? If so, how do I get the dimensions right? Or is there a better way to get the aspect ratio right? I have the viewfinder on my camcorder marked to show a 4:3 ratio so I'm not worried about cutting out parts of the scene. Please let me know if this can be done.
Thank You
User avatar ttguy
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You could just try a 4:3 project setting like DVD/DV PAL or DVD/DV NTSC. And then when you import your 16:9 clip decline the offer to change your project settings.
Then render the project with the DVD group choosing PAL 4:3 VOB or NTSC 4:3 VOB.
When I just experimented with this I got what looks like letter boxed 4:3. Which I guess is not what you want. You might need to experiment a bit.

My advice is to do some test renders AND play them back on your final device. Because I have had some wierd stuff happen when the footage is played on DVD player through a TV. The DVD player and TVs can try and be smart with your footage and they can some times cause a result that is not ideal. It might look good on the software player on the PC but be a different aspect ratio on the final device.
User avatar ttguy
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The second answer here http://superuser.com/questions/343951/h ... -the-edges might give you some joy. It has some info on using ffmpeg to do this job.
User avatar ttguy
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ffmpeg -i mt_Yasur_volcano.mp4 -vf "crop=w=540:h=576" -vcodec libx264 -acodec copy mt_Yasur_volcano_cropped2.mp4
This crops the footage to 540w x 576 h. And creates a 4:3 video. But why 540wide?

The input footage is 720x576 with a Sample Aspect Ratio (SAR) of 1.4222 [note SAR is synonymous with Pixel Aspect Ratio (PAR) ]
You can learn this info from ffprobe (64:45 = 1.4222)
ffprobe mt_Yasur_volcano.mp4
Duration: 00:02:03.90, start: 0.000000, bitrate: 2150 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x576 [SAR 64:45 DAR 16:9], 1964 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc (default)

Now 720x576 is not 16:9. But when you account for the SAR this is 1024 x 576 which is 16:9.
To make a 1024 x 576 video 4:3 you need to make it 1024 X 3 / 4 = 768 pixels wide.
But in our video this is apparent pixel count for the width. Our actual pixels are not square. To calculate how many non-square pixels are needeed to give an apparent width of 768 calculate = 768/SAR = 768/1.4222=540
Hence we crop tp 540w x 576h to get 4:3

doco on ffmpeg crop http://ffmpeg.org/ffmpeg-filters.html#crop
winterfire
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I think I know what you are trying to do. First select pan and zoom. Then select size if the original is 1080 change it to 1440x1080. If the original is 720, change it to 970x720. That will make the video 4:3 ratio. Then render the video and resize it as 1440x1080 or 970x720 depending on the size of the video. When you show the finished video on your projector, it will be 4:3.



 
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