ColorBars
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These colors are at "75%" of maximum, per common broadcast practice. <br> | These colors are at "75%" of maximum, per common broadcast practice. <br> | ||
| − | You may occasionally see "100%" color bars | + | You may occasionally see "100%" color bars.<sup>[http://trac.ffmpeg.org/wiki/FilteringGuide#multipleinputoverlayin2x2grid]</sup> |
==== PLUGE ==== | ==== PLUGE ==== | ||
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The -I and +Q bars are vestigial artifacts of NTSC analog TV and are not really used any more. | The -I and +Q bars are vestigial artifacts of NTSC analog TV and are not really used any more. | ||
| − | The -4, 0 and +4 IRE bars can be used to set your monitor brightness. The -4 IRE and 0 IRE bars should have the same apparent brightness (they should be as dark as the monitor can display), and the +4 should be a little brighter. If you can see the -4 bar, your monitor brightness is set too high; if you ''cannot'' see the +4 bar, your monitor brightness is set too low.<sup>[http://www.spearsandmunsil.com/portfolio/setting-the-brightness-control-2]</sup> | + | The -4, 0 and +4 IRE bars can be used to set your monitor brightness – ''assuming'' your playback chain expands [[Luminance_levels#What_are_luminance_levels.3F|TV range]] (16-235) to full-range (0-255) as shown in the images above. The -4 IRE and 0 IRE bars should have the same apparent brightness (they should be as dark as the monitor can display), and the +4 should be a little brighter. If you can see the -4 bar, your monitor brightness is set too high; if you ''cannot'' see the +4 bar, your monitor brightness is set too low.<sup>[http://www.spearsandmunsil.com/portfolio/setting-the-brightness-control-2]</sup> |
Note, the pluge signal goes out of the 16-235 range in ''two'' places: [[Wikipedia:YIQ|-I]] (where '''R'''=0) and the -4 bar. | Note, the pluge signal goes out of the 16-235 range in ''two'' places: [[Wikipedia:YIQ|-I]] (where '''R'''=0) and the -4 bar. | ||
Revision as of 19:10, 13 March 2016
Contents |
ColorBars ( [ int width, int height, string pixel_type ] )
Produces a video clip containing SMPTE color bars (Rec. ITU-R BT.801-1) scaled to any image size.
By default, a 640×480, RGB32, TV range, 29.97 fps, 1 hour long clip is produced.
- int width = 640
- int height = 480
- Set size of the returned clip.
- string pixel_type = "RGB32"
- Set color format of the returned clip.
- May be any of the following: "YUY2", "YV12", "YV24" (v2.60), or (default) "RGB32".
ColorBarsHD ( [ int width, int height, string pixel_type ] )
Added in v2.60, ColorBarsHD produces a video clip containing SMPTE color bars
(Rec. ITU-R BT.709 / arib std b28 v1.0) scaled to any image size.
By default, a 1288×720, YV24, TV range, 29.97 fps, 1 hour long clip is produced.
- int width = 1288
- int height = 720
- Set size of the returned clip.
- string pixel_type = "YV24"
- Set color format of the returned clip. Must be "YV24".
TV range
For both filters, in all color formats, luminance levels are TV range, where 0 IRE "black"=16
and 100 IRE "white"=235, within a total possible range of 0-255.
Color bar R G B Y U V 75% White 180 180 180 180 128 128 75% Yellow 180 180 16 162 44 142 75% Cyan 16 180 180 131 156 44 75% Green 16 180 16 112 72 58 75% Magenta 180 16 180 84 184 198 75% Red 180 16 16 65 100 212 75% Bue 16 16 180 35 212 114
These colors are at "75%" of maximum, per common broadcast practice.
You may occasionally see "100%" color bars.[1]
PLUGE
The lower part of the frame is called the PLUGE (also lowercase: "pluge") signal.
From left to right it consists of: -I, white, +Q, then a series of black and near-black bars: 0, -4, 0, +4 and 0 IRE.
This section documents the ColorBars pluge only; ColorBarsHD's pluge is similar, but dispenses with -I and +Q
PLUGE Element R G B Y U V -I 0 58 98 16 158 95 100% White 235 235 235 235 128 128 +Q 59 15 126 16 174 149 0 IRE (Black) 16 16 16 16 128 128 -4 IRE 7 7 7 7 128 128 0 IRE (Black) 16 16 16 16 128 128 +4 IRE 25 25 25 25 128 128 0 IRE (Black) 16 16 16 16 128 128
"100% White" could also be called "100 IRE White."
The -I and +Q bars are vestigial artifacts of NTSC analog TV and are not really used any more.
The -4, 0 and +4 IRE bars can be used to set your monitor brightness – assuming your playback chain expands TV range (16-235) to full-range (0-255) as shown in the images above. The -4 IRE and 0 IRE bars should have the same apparent brightness (they should be as dark as the monitor can display), and the +4 should be a little brighter. If you can see the -4 bar, your monitor brightness is set too high; if you cannot see the +4 bar, your monitor brightness is set too low.[2]
Note, the pluge signal goes out of the 16-235 range in two places: -I (where R=0) and the -4 bar.
More information about the colorbars and the PLUGE can be found on the colorbars theory page.
Audio
For both filters, an audio tone is also generated. The tone is a 440Hz sine at 48KHz sample rate, 16 bit, stereo. The tone pulses in the right speaker, being turned on and off once every second. Level is 0 dBFS.
You can use Amplify to set a softer level (0dB can be a little deafening!)
ColorBarsHD AmplifyDB(-20)
Broadcasting organizations usually specify an "alignment tone" accompanying colorbars at anywhere from -12 to -20 dBFS; if sending materials to another party, be sure to get their preferred alignment tone level. The exact level doesn't matter as long as all parties agree to it.
Miscellaneous
- Note, that for example
ColorBars(pixel_type="YUY2")
- ...is equivalent to
ColorBars(pixel_type="RGB32") ConvertToYUY2(matrix="PC.601") # "PC.601" / "PC.709" don't scale the luma range
- When directly generating YUV format data, the color transitions are arranged to occur on a chroma-aligned boundary.
Changes
| v2.60 |
|
| v2.56 | Added pixel_type="YUY2"/"YV12". |
