FFMPEG. Overtake video in mobile phone format. Compliance with proportions. Operand pad
It is necessary to overtake the film from MKV with dimensions of 1280 x 536 to the size of a mobile phone with dimensions of 320 x 240 and keep the proportions. To mp4 format with audio to ac3
I have this method of calculating proportions (the most standard is mathematical):
If from 1280 it should be 320 , then we need to calculate the coefficient for calculating the short side, for this we divide 1280 by 320 , we get 4 . So, to calculate the short side, we need to divide 536 by 4 . We get 134 .
So, if we set the resulting size, then we will succeed. As if not so!
The phone has a screen of 320 x 240 , and if our video is 320 x 134 we launch on the phone, then it will stretch the short side of 134 pixels to 240 , that is, the characters in our movie will have elongated faces, etc. So you need to bring the final file to a size of 320 x 240 , filling the missing pixels with black color at the top and bottom. To do this, made a special video filter PAD .
Let's estimate how much you need to add to 134 to make 240 ? Very simple: subtract 134 from 240 , it turned out 106 . These 106 pixels need to be added to our video to get it right. But we do not want this strip with a height of 106 pixels to be just above or below, for this we divide this 106 px into two 53 px bands and place it above and below.
Decrypt -vf "scale = 320: 135, pad = 320: 240: 0: 53: black, unsharp"
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scale = 320: 135 - specify the PROPORTIONAL size of the output file to the original film size.
pad = 320: 240: 0: 53: black - 320: 240 - the actual screen size of the phone,: 0: 53 - on the scale X - shift 0 , on the scale Y - shift 53 pixels.
: black, unsharp - Stripes will be black (black) color. You can add unsharp definition. And you can not add. This filter also has settings. Need to read.
I have this method of calculating proportions (the most standard is mathematical):
If from 1280 it should be 320 , then we need to calculate the coefficient for calculating the short side, for this we divide 1280 by 320 , we get 4 . So, to calculate the short side, we need to divide 536 by 4 . We get 134 .
So, if we set the resulting size, then we will succeed. As if not so!
The phone has a screen of 320 x 240 , and if our video is 320 x 134 we launch on the phone, then it will stretch the short side of 134 pixels to 240 , that is, the characters in our movie will have elongated faces, etc. So you need to bring the final file to a size of 320 x 240 , filling the missing pixels with black color at the top and bottom. To do this, made a special video filter PAD .
Let's estimate how much you need to add to 134 to make 240 ? Very simple: subtract 134 from 240 , it turned out 106 . These 106 pixels need to be added to our video to get it right. But we do not want this strip with a height of 106 pixels to be just above or below, for this we divide this 106 px into two 53 px bands and place it above and below.
ffmpeg -i kino.mkv -vcodec mpeg4 -vb 500K -acodec libfaac -ar 44100 -ab 256K -ac 2 -vf «scale=320:135,pad=320:240:0:53:black,unsharp» -vol 700 -y kino.mp4Decrypt -vf "scale = 320: 135, pad = 320: 240: 0: 53: black, unsharp"
')
scale = 320: 135 - specify the PROPORTIONAL size of the output file to the original film size.
pad = 320: 240: 0: 53: black - 320: 240 - the actual screen size of the phone,: 0: 53 - on the scale X - shift 0 , on the scale Y - shift 53 pixels.
: black, unsharp - Stripes will be black (black) color. You can add unsharp definition. And you can not add. This filter also has settings. Need to read.
Source: https://habr.com/ru/post/129461/
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