ffmpeg scalling resizing without decrease quality

If you need to simply resize your video to a specific size (e.g 320x240), you can use the scale filter in its most basic form:

ffmpeg -i input.avi -vf scale=1280:720 output.avi

ffmpeg -i input.avi -vf scale=7680:4320 -crf 10 output.avi

This below is fast when encoding, but bad quality

ffmpeg -i input.avi -acodec aac -vcodec mpeg4 -mbd 2 -cmp 2 -subcmp 2 -s 7680x4320 output.avi

Same works for images too:

ffmpeg -i input.jpg -vf scale=320:240 output_320x240.png

Video Resolution

To fit the player perfectly, encode at these resolutions:

Youtube	Resolution	Pixel	Ratio	Type	MegaPixel	Information
	122880x69120	128K			8493
34560p	61440x34560	64K			2123	4x8K; 64x1080p
	46080x25920	48K			1194
	30720x17280	32K			530,8
8640p	15360x8640	16K			132,71	4x8K; 64x1080p
	8192×4320	8K	17:09		35,4
4320p	7680x4320	8K	16:09	FULL HD	33,2
	8192x5120	8K	16:10		33,2
	8192x8192	8K	1:01		67,1
2160p	3840x2160	4K	1,78:1	UHD	8,29	Ultra High Defination
	3840x1600	4k	2,4:1	Ultra Wide
	4096x2160	4K	1,90:1	Native
	4096x1716	4k	2,29:1	Cinema Scope
	3996x2160	4K	1,85:1	Flat Crop
1440p	2560x1440	2K		QHD	4	Quad High Defination
	2048×1080	2K	1,90:1	Native
	1998x1080	2K	1,85:1	Flat Crop
	2048x858	2K	2,39:1	Cinema Scope
1080p	1920x1080		16:9	FHD	2	Full High Defination
	1440X1080		4:3
	1620x1080		3:2
720p	1280x720			HD		High Defination
480p	854x480
360p	640x360
240p	426x240

• Analog and early digital
  • 352×240 : Video CD
  • 333×480 : VHS, Video8, Umatic
  • 350×480 : Betamax
  • 420×480 : Super Betamax, Betacam
  • 460×480 : Betacam SP, Umatic SP, NTSC (Over-The-Air TV)
  • 580×480 : Super VHS, Hi8, LaserDisc
  • 700×480 : Enhanced Definition Betamax, Analog broadcast limit (NTSC)
  • 768×576 : Analog broadcast limit (PAL, SECAM)
• Digital
  • 500×480  : Digital8
  • 720×480  : D-VHS, DVD, miniDV, Digital Betacam (NTSC)
  • 720×480  : Widescreen DVD (anamorphic) (NTSC)
  • 720x576  : D-VHS, DVD, miniDV, Digital8, Digital Betacam (PAL/SECAM)
  • 720x576  : Widescreen DVD (anamorphic) (PAL/SECAM)
  • 1280×720  : D-VHS, HD DVD, Blu-ray, HDV (miniDV)
  • 1440×1080  : HDV (miniDV)
  • 1920×1080  : HDV (miniDV), AVCHD, HD DVD, Blu-ray, HDCAM SR
  • 1998x1080  : 2K Flat (1.85:1)
  • 2048×1080  : 2K Digital Cinema
  • 3840x2160  : 4K UHDTV
  • 4096×2160  : 4K Digital Cinema
  • 7680×4320  : 8K UHDTV
  • 15360×8640 : 16K Digital Cinema
  • 61440×34560 : 64K Digital Cinema
  • Sequences from newer films are scanned at 2,000, 4,000, or even 8,000 columns, called 2K, 4K, and 8K, for quality visual-effects editing on computers.
  • IMAX, including IMAX HD and OMNIMAX: approximately 10,000×7,000 (7,000 lines) resolution. It is about 70 Mpix, which is currently highest-resolution single-sensor digital cinema camera (as of January 2012)

Televisions

Televisions are of the following resolutions:

• Standard-definition television (SDTV):
  • 480i (NTSC-compatible digital standard employing two interlaced fields of 243 lines each)
  • 576i (PAL-compatible digital standard employing two interlaced fields of 288 lines each)
• Enhanced-definition television (EDTV):
  • 480p (720 × 480 progressive scan)
  • 576p (720 × 576 progressive scan)
• High-definition television (HDTV):
  • HD (1280 × 720 progressive scan)
  • Full HDi (1920 × 1080 split into two interlaced fields of 540 lines)
  • Full HD (1920 × 1080 progressive scan)
• Ultra-high-definition television (UHDTV):
  • 4K UHD (3840 × 2160 progressive scan)
  • True 4K (4096 × 2160)
  • 8K UHD (7680 × 4320 progressive scan)
  • True 8K (8192 × 4320)

• 4:3 aspect ratio resolutions: 640×480, 800×600, 960×720, 1024×768, 1280×960, 1400×1050, 1440×1080 , 1600×1200, 1856×1392, 1920×1440, and 2048×1536.
• 16:10 aspect ratio resolutions: - 1280×800, 1440×900, 1680×1050, 1920×1200 and 2560×1600.
• 16:9 aspect ratio resolutions: 1024×576, 1152×648, 1280×720, 1366×768, 1600×900, 1920×1080, 2560×1440 and 3840×2160.

Standard display resolutions	Widescreen display resolutions		Resolution - Aspect ratio
160×120	240×160
320×200	320×240		720x480-----3:2
640×200	432×240		1152x768-----3:2
640×350	480×270		1280x854-----3:2
640×480	480×320		1440x960-----3:2
720×348	640×400		2880x1920----3:2
800×600	800×480
1024×768	854×480		___________________
1152×864	1024×576
1280×1024	1280×720		320x240-----4:3
1400×1050	1280×768		640x480-----4:3
1600×1200	1280×800		800x600-----4:3
2048×1536	1366×768		1024x768-----4:3
2560×2048	1366×900		1152x864-----4:3
3200×2400	1440×900		1280x960-----4:3
4096×3072	1600×900		1400x1050-----4:3
5120×4096	1680×945		1600x1200-----4:3
6400×4800	1680×1050		2048x1536-----4:3
	1920×1080 (1080p)		3200x2400-----4:3
	1920×1200		4000x3000-----4:3
	2048×1152		6400x4800-----4:3
	2560×1440
	2560×1600		___________________
	3200×2048
	3840×2160		800x480-----5:3
	3200×2400		1280x768-----5:3
	5120×2880
	5120×3200		___________________
	5760×3240
	6400×4096		1280x1024-----5:4
	7680×4320		2560x2048-----5:4
	7680×4800		5120x4096-----5:4
	15360×8640
			___________________
			852x480-----16:9
			1280x720-----16:9
			1365x768-----16:9
			1600x900-----16:9
			1920x1080-----16:9
			___________________
			320x200-----16:10
			640x400-----16:10
			1280x800-----16:10
			1440x900-----16:10
			1680x1050-----16:10
			1920x1200-----16:10
			2560x1600-----16:10
			3840x2400-----16:10
			7680x4800-----16:10

• 4:3 aspect ratio resolutions: 640×480, 800×600, 960×720, 1024×768, 1280×960, 1400×1050, 1440×1080 , 1600×1200, 1856×1392, 1920×1440, and 2048×1536.
• 16:10 aspect ratio resolutions: - 1280×800, 1440×900, 1680×1050, 1920×1200 and 2560×1600.
• 16:9 aspect ratio resolutions: 1024×576, 1152×648, 1280×720, 1366×768, 1600×900, 1920×1080, 2560×1440 and 3840×2160.