Description

ColorBars is a filter for generating test signals. The output is a single frame of color bars according to SMPTE RP 219-1, 219-2, or ITU-R BT.2111-2. For NTSC, the bar pattern is described in SMPTE EG 1. For PAL, EBU bars are generated.

SMPTE RP 219-2 gives explicit color bar values in 10-bit and 12-bit Y'Cb'Cr'. ITU BT.2111-2 gives explicit color bar values in 10-bit and 12-bit R'G'B'. These values are used directly instead of being generated at runtime.

Usage

colorbars.ColorBars([int resolution=3, int format=vs.YUV444P12, int hdr=0, int wcg=0, int compatability=2, int subblack=1, int superwhite=1, int iq=1, int halfline=0])

• resolution: Ten different systems are supported as follows

  • 0 - NTSC (BT.601)
  • 1 - PAL (BT.601)
  • 2 - 720p
  • 3 - 1080i/p
  • 4 - 2K
  • 5 - UHDTV1/UHD
  • 6 - 4K
  • 7 - UHDTV2/8K
  • 8 - NTSC (4fsc)
  • 9 - PAL (4fsc)

• format: Either vs.YUV444P10 or vs.YUV444P12 are supported in SDR mode. Either vs.RGB30 or vs.RGB36 are supported in HDR mode. This is because SMPTE defines bar values in terms of Y'Cb'Cr' and ITU uses R'G'B'.

• hdr: Non-zero values enable BT.2111 HDR mode as follows

  • 0 - SDR
  • 1 - HLG
  • 2 - PQ
  • 3 - PQ (full range)

• wcg: Enable ITU-R BT.2020, aka wide color gamut. Only valid with UHD and higher resolutions. Required for 8K, although ColorBars does not enforce this and will generate 8K Rec.709 with a warning. No effect when hdr > 0.

• compatability: Controls how pedantic you want to be, especially for legacy NTSC/PAL systems. No effect when hdr > 0.

  • 0 - Use ideal bar dimensions, rounded to the nearest integer. Bar widths are specified as fractions of the active picture and can be odd.
  • 1 - Use even bar dimensions to facilitate chroma subsampling. Conversions to YUV420 or YUV422 later may be problematic otherwise.
  • 2 - For NTSC and PAL, ignore blanking. The entire line contains the active image. For HD and higher resolutions, use dimensions that are compatible with chroma subsampling and with 4:3 center-cut downconversion. For UHD/4K and 8K, use multiples of four and eight respectively for 2SI compatibility.

NTSC and PAL both have an active digital width of 720 pixels when using BT.601 (13.5 MHz) sampling. 525-line NTSC has 710.85x484 active picture plus two half lines. 712 is used in modes 0 and 1 with 4 blanking pixels on each side. 625-line PAL has 702x574 active picture plus two half lines. 702 is used in mode 0, with 9 blanking pixels on each side. 704 is used in mode 1, with 8 blanking pixels on each side.

4fsc NTSC (14.318 MHz) has 768 digital active samples. 757.27 samples are active (52+8/9 us). Mode 0 is 758 wide with 5 blanking pixels on each side. Mode 1 is 760 wide with 4 blanking pixels on each side. 4fsc PAL (17.734 MHz) has 948 digital active samples. 922 samples are active (52 us) in modes 0 and 1 with 12 blanking pixels on each side.

NTSC modes 0 and 1 have 486 active lines. DVB/ATSC/DV/HDMI use 480 lines, like in mode 2.

• subblack: Controls whether to generate the below black ramp in the middle third of the first 0% black patch on the bottom row. Only valid with HD and higher resolutions. No effect when hdr > 0.

• superwhite: Controls whether to generate an above white ramp in the middle third of the 100% white chip on the bottom row. Only valid with HD and higher resolutions. No effect when hdr > 0.

• iq: Controls the second patch of rows 2 and 3. Only valid with HD and higher resolutions. No effect when hdr > 0. Mode 1 and 2 are not valid if wcg=1.

  • 0 - 75% white and 0% black
  • 1 - -I and +Q
  • 2 - +I and 0% black
  • 3 - 100% white and 0% black

The +I/-I/+Q values are conveniently specified in RP 219 for systems with Rec.709 primaries (HD up to 4K). For NTSC, the values were calculated and later verified to match an Evertz SDI test signal generator. Note that converting from YUV to RGB will produce out of range values.

• halfline: For ultimate pedantry, perform halfline blanking on analog lines 284/263 (NTSC) and 23/623 (PAL). Applies to NTSC and PAL resolutions only.

Examples

Note that bar transitions are not instant. RP 219 requires proper shaping. Rise and fall times are 4 samples (10% to 90%) and +/-10% of the nominal value and the shape is recommended to be an integrated sine-squared pulse. Shaping may be integrated into ColorBars later, but for now you can apply a horizontal blur.

# Generate 30 seconds of 1080i HD bars
c = core.colorbars.ColorBars(format=vs.YUV444P10)
c = core.std.SetFrameProp(clip=c, prop="_FieldBased", intval=vs.FIELD_TOP)
c = core.std.Convolution(c,mode="h",matrix=[1,2,4,2,1])
c = core.resize.Point(clip=c,format=vs.YUV422P10)
c = c * (30 * 30000 // 1001)
c = core.std.AssumeFPS(clip=c, fpsnum=30000, fpsden=1001)

# Generate 60 seconds of annoyingly "correct" NTSC bars
c = core.colorbars.ColorBars(format=vs.YUV444P12, resolution=0, compatability=0)
c = core.std.SetFrameProp(clip=c, prop="_FieldBased", intval=vs.FIELD_BOTTOM)
c = core.std.Crop(c, 4, 4)
c = core.std.Convolution(c,mode="h",matrix=[1,2,4,2,1])
c = core.resize.Point(clip=c,format=vs.YUV422P8)
c = c * (60 * 30000 // 1001)
c = core.std.AssumeFPS(clip=c, fpsnum=30000, fpsden=1001)

# Generate UHD Bars with Rec.2020 primaries
c = core.colorbars.ColorBars(format=vs.YUV444P12, resolution=5, wcg=1)
c = core.std.Convolution(c,mode="h",matrix=[1,2,4,2,1])
c = core.resize.Point(clip=c,format=vs.YUV422P10)
c = core.std.AssumeFPS(clip=c, fpsnum=50, fpsden=1)

# Generate HLG UHD Bars
c = core.colorbars.ColorBars(format=vs.RGB30, resolution=5, hdr=1)
c = core.std.Convolution(c,mode="h",matrix=[1,2,4,2,1])
c = core.resize.Point(clip=c,format=vs.YUV422P10,matrix_s="2020ncl")

Installation

pip

pip install vapoursynth-colorbars

Meson (from source)

meson setup build
meson compile -C build

Requires VapourSynth >= R74.

Windows (MinGW-w64 one-shot)

gcc -shared -o colorbars.dll colorbars.c -I include/vapoursynth -O3 -std=c99 -Wall