The [SMPTE 170M] standard defines the colorspace used by NTSC and PAL and by SDTV in general. The default Y'CbCr encoding is V4L2_YCBCR_ENC_601. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

The red, green and blue chromaticities are also often referred to as the SMPTE C set, so this colorspace is sometimes called SMPTE C as well.

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. This conversion to Y'CbCr is identical to the one defined in the [ITU BT.601] standard and this colorspace is sometimes called BT.601 as well, even though BT.601 does not mention any color primaries.

The default quantization is limited range, but full range is possible although rarely seen.

The [ITU BT.709] standard defines the colorspace used by HDTV in general. The default Y'CbCr encoding is V4L2_YCBCR_ENC_709. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

The full name of this standard is Rec. ITU-R BT.709-5.

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5].

The default quantization is limited range, but full range is possible although rarely seen.

The V4L2_YCBCR_ENC_709 encoding described above is the default for this colorspace, but it can be overridden with V4L2_YCBCR_ENC_601, in which case the BT.601 Y'CbCr encoding is used.

Two additional extended gamut Y'CbCr encodings are also possible with this colorspace:

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. The non-standard xvYCC 709 or xvYCC 601 encodings can be used by selecting V4L2_YCBCR_ENC_XV709 or V4L2_YCBCR_ENC_XV601. The xvYCC encodings always use full range quantization.

The [sRGB] standard defines the colorspace used by most webcams and computer graphics. The default Y'CbCr encoding is V4L2_YCBCR_ENC_SYCC. The default Y'CbCr quantization is full range. The chromaticities of the primary colors and the white reference are:

These chromaticities are identical to the Rec. 709 colorspace.

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. The V4L2_YCBCR_ENC_SYCC quantization is always full range. Although this Y'CbCr encoding looks very similar to the V4L2_YCBCR_ENC_XV601 encoding, it is not. The V4L2_YCBCR_ENC_XV601 scales and offsets the Y'CbCr values before quantization, but this encoding does not do that.

The [AdobeRGB] standard defines the colorspace used by computer graphics that use the AdobeRGB colorspace. This is also known as the [opRGB] standard. The default Y'CbCr encoding is V4L2_YCBCR_ENC_601. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. This transform is identical to one defined in SMPTE 170M/BT.601. The Y'CbCr quantization is limited range.

The [ITU BT.2020] standard defines the colorspace used by Ultra-high definition television (UHDTV). The default Y'CbCr encoding is V4L2_YCBCR_ENC_BT2020. The default R'G'B' quantization is limited range (!), and so is the default Y'CbCr quantization. The chromaticities of the primary colors and the white reference are:

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. The Y'CbCr quantization is limited range.

There is also an alternate constant luminance R'G'B' to Yc'CbcCrc (V4L2_YCBCR_ENC_BT2020_CONST_LUM) encoding:

Yc' is clamped to the range [0…1] and Cbc and Crc are clamped to the range [-0.5…0.5]. The Yc'CbcCrc quantization is limited range.

The [SMPTE 240M] standard was an interim standard used during the early days of HDTV (1988-1998). It has been superseded by Rec. 709. The default Y'CbCr encoding is V4L2_YCBCR_ENC_SMPTE240M. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

These chromaticities are identical to the SMPTE 170M colorspace.

Yc' is clamped to the range [0…1] and Cbc and Crc are clamped to the range [-0.5…0.5]. The Y'CbCr quantization is limited range.

This standard defines the colorspace used by NTSC in 1953. In practice this colorspace is obsolete and SMPTE 170M should be used instead. The default Y'CbCr encoding is V4L2_YCBCR_ENC_601. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

Note that this colorspace uses Illuminant C instead of D65 as the white reference. To correctly convert an image in this colorspace to another that uses D65 you need to apply a chromatic adaptation algorithm such as the Bradford method.

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is identical to one defined in SMPTE 170M/BT.601.

The [EBU Tech 3213] standard defines the colorspace used by PAL/SECAM in 1975. In practice this colorspace is obsolete and SMPTE 170M should be used instead. The default Y'CbCr encoding is V4L2_YCBCR_ENC_601. The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the white reference are:

Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range [-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is identical to one defined in SMPTE 170M/BT.601.

This colorspace defines the colorspace used by most (Motion-)JPEG formats. The chromaticities of the primary colors and the white reference are identical to sRGB. The Y'CbCr encoding is V4L2_YCBCR_ENC_601 with full range quantization where Y' is scaled to [0…255] and Cb/Cr are scaled to [-128…128] and then clipped to [-128…127].

Note that the JPEG standard does not actually store colorspace information. So if something other than sRGB is used, then the driver will have to set that information explicitly. Effectively V4L2_COLORSPACE_JPEG can be considered to be an abbreviation for V4L2_COLORSPACE_SRGB, V4L2_YCBCR_ENC_601 and V4L2_QUANTIZATION_FULL_RANGE.