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Transfer Characteristics

Transfer characteristics, also known as transfer functions, represent the gamma function of a video--that is, how to convert from a gamma-compressed video to one that is in linear light. These are sometimes also called EOTF and OETF functions.

As with primaries, the integer values are defined within universal specifications, and as such they will be the same across all encoding and playback tools.

The following values are available:

1: BT.1886​

BT.1886 is the standard used for most modern, SDR video, and is a safe default assumption.

This transfer function is used in the following standards:

  • Rec. ITU-R BT.709-6
  • Rec. ITU-R BT.1361-0 conventional colour gamut system (historical)

2: Unspecified​

This value indicates that no transfer function is set for the video, and the player must decide which value to use.

mpv will always assume BT.1886 in this case.

4: BT.470M​

BT.470M is a standard that was used in analog television systems in the United States. This transfer represents a power function with a gamma of 2.2.

This transfer function is used in the following standards:

  • Rec. ITU-R BT.470-6 System M (historical)
  • United States National Television System Committee 1953 Recommendation for transmission standards for color television
  • United States Federal Communications Commission (2003) Title 47 Code of Federal Regulations 73.682 (a) (20)
  • Rec. ITU-R BT.1700-0 625 PAL and 625 SECAM

5: BT.470BG​

BT.470BG is a standard that was used for European (PAL) television systems and DVDs. This transfer represents a power function with a gamma of 2.8.

6: SMPTE 170M​

SMPTE 170M is a stanrard that was used for NTSC television systems and DVDs. Its transfer function is equivalent to BT.1886.

This transfer function is used in the following standards:

  • Rec. ITU-R BT.601-7 525 or 625
  • Rec. ITU-R BT.1358-1 525 or 625 (historical)
  • Rec. ITU-R BT.1700-0 NTSC
  • SMPTE ST 170 (2004)

7: SMPTE 240M​

SMPTE 240M was an interim standard used during the early days of HDTV (1988-1998).

8: Linear​

This value indicates that the content is already in linear light.

9: Logarithmic 100​

Indicates a logarithmic transfer function with a 100:1 range.

10: Logarithmic 316​

Indicates a logarithmic transfer function with a (100 * sqrt(10)):1 range.

11: XVYCC​

Used in standard IEC 61966-2-4. I have no idea what this actually is.

12: BT.1361E​

This was intended to be a standard for "future" television systems, but it never really came into use.

13: sRGB​

Represents the sRGB colorspace.

This transfer function is used in the following standards:

  • IEC 61966-2-1 sRGB (with MatrixCoefficients equal to 0)
  • IEC 61966-2-1 sYCC (with MatrixCoefficients equal to 5)

14: BT.2020 10-bit​

Typically used with ultra-high-definition 10-bit SDR video. Its transfer function is equivalent to BT.1886.

15: BT.2020 12-bit​

Typically used with ultra-high-definition 12-bit SDR video. Its transfer function is equivalent to BT.1886.

16: PQ aka SMPTE 2084​

PQ is the most widely used transfer function for HDR content. It allows for a wider range of luminance to be represented than conventional transfer functions.

This transfer function is used in the following standards:

  • SMPTE ST 2084 (2014) for 10-, 12-, 14- and 16-bit systems
  • Rec. ITU-R BT.2100-2 perceptual quantization (PQ) system

17: SMPTE 428​

SMPTE 428 is used for D-Cinema Distribution Masters, aka DCDM.

18: HLG aka Hybrid Log-Gamma​

HLG is an alternative transfer function for HDR content used by some televisions.

This transfer function is used in the following standards:

  • ARIB STD-B67 (2015)
  • Rec. ITU-R BT.2100-2 hybrid log- gamma (HLG) system