Convert

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Revision as of 15:40, 8 November 2015

ConvertToRGB(clip [, string matrix] [, bool interlaced] [, string ChromaInPlacement] [, string chromaresample])
ConvertToRGB24(clip [, string matrix] [, bool interlaced] [, string ChromaInPlacement] [, string chromaresample])
ConvertToRGB32(clip [, string matrix] [, bool interlaced] [, string ChromaInPlacement] [, string chromaresample])
ConvertToYUY2(clip [, bool interlaced] [, string matrix] [, string ChromaInPlacement] [, string chromaresample])
ConvertBackToYUY2(clip [, string matrix]
ConvertToY8(clip [, string matrix])
ConvertToYV411(clip [, bool interlaced] [, string matrix] [, string ChromaInPlacement] [, string chromaresample])
ConvertToYV12(clip [, bool interlaced] [, string matrix] [, string ChromaInPlacement] [, string chromaresample] [, string ChromaOutPlacement])
ConvertToYV16(clip [, bool interlaced] [, string matrix] [, string ChromaInPlacement] [, string chromaresample])
ConvertToYV24(clip [, bool interlaced] [, string matrix] [, string ChromaInPlacement] [, string chromaresample]))

Contents

Colorformats

The following formats can be converted to and from.

colorformats planar/interleaved chroma resolution
RGB interleaved full chroma - 4:4:4
RGB24 interleaved full chroma - 4:4:4
RGB32 interleaved full chroma - 4:4:4
YUY2 interleaved chroma shared between 2 pixels - 4:2:2
Y8 planar/interleaved no chroma - 4:0:0
YV411 planar chroma shared between 4 pixels - 4:1:1
YV12 planar chroma shared between 2x2 pixels - 4:2:0
YV16 planar chroma shared between 2 pixels - 4:2:2
YV24 planar full chroma - 4:4:4

Options

matrix
Default "Rec601". Controls the colour coefficients and scaling factors used in RGB - YUV conversions.
  • "Rec601" : Uses Rec.601 coefficients; scale full range [0..255] RGB to TV range [16..235] YUV, and vice versa.
  • "Rec709" : Uses Rec.709 coefficients; scale full range [0..255] RGB to TV range [16..235] YUV, and vice versa.
  • "PC.601" : Uses Rec.601 coefficients, keep full range.
  • "PC.709" : Uses Rec.709 coefficients, keep full range.
  • "AVERAGE" : Uses averaged coefficients, keep full range. (So the luma becomes the average of the RGB channels.)
interlaced
Default false. Use interlaced layout for YV12 conversions.
Since v2.51/v2.52 an optional interlaced parameter is added (interlaced=false is the default operation). When set to false it is assumed that clip is progressive, when set to true it is assumed that clip is interlaced. This option is added because for example (assuming clip is interlaced YV12):
SeparateFields(clip)
ConvertToYUY2()
Weave()
is upsampled incorrectly. Instead it is better to use:
ConvertToYUY2(clip, interlaced=true)
Note, the interlaced=true setting only does something if the conversion YV12 <-> YUY2/RGB is requested, otherwise it's simply ignored. More about it can be found here.
ChromaInPlacement
(added in v2.60): This determines the chroma placement when converting from YV12. It can be "MPEG2" (default), "MPEG1" and "DV".
chromaresample
(added in v2.60): This determines which resizer is used in the conversion. It is used when the chroma resolution of the source and target is different. It can be all resamplers ("point", "bilinear", "bicubic", "lanczos", "lanczos4", "blackman", "spline16", "spline36", "spline64", "gauss" and "sinc"), default is "bicubic".
ChromaOutPlacement
(added in v2.60): This determines the chroma placement when converting to YV12. It can be "MPEG2" (default), "MPEG1" and "DV".


AviSynth prior to v2.60 can deal internally with three color formats, RGB, YUY2 and YV12. These six filters convert between them. If the video is already in the specified format, it will be passed through unchanged. (RGB is assumed throughout this doc to mean RGBA.) ConvertToRGB converts to RGB32 unless your clip is RGB24. If you need 24-bit RGB for some reason, use ConvertToRGB24 explicitly and ConvertToRGB32 to do the reverse.

In v2.60 the following additional formats are supported: Y8 greyscale (it is both planar and interleaved since it contains no chroma; 4:0:0), YV411 (planar; YUV 4:1:1), YV16 (a planar version of YUY2; 4:2:2) and YV24 (planar; YUV 4:4:4).

Syntax and operation of ConvertToRGB24 are identical to ConvertToRGB, except that the output format is 24-bit; if the source is RGB32, the alpha channel will be stripped.

When the target format is the same as the source format, the original clip will be returned. Except for the following situation: When both formats are YV12, the source clip will be processed when ChromaInPlacement and ChromaOutPlacement differ. So this can be used to change the chroma placement in a YV12 clip.

Examples

Contrary to what one might expect, there is no unique way of converting YUV to RGB. In AviSynth the two most common ones are implemented: Rec.601 and Rec.709 (named after their official specifications). Although it will not be correct in all cases, the following should be correct in most cases:

The first one (Rec.601) should be used when your source is DivX/XviD or some analogue capture: 

ConvertToRGB(clip)

The second one (Rec.709) should be used when your source is DVD or HDTV: 

ConvertToRGB(clip, matrix="rec709")

In v2.56, the reverse is also available, that is 

ConvertToYUY2(clip, matrix="rec709") or ConvertToYV12(clip, matrix="rec709")

In v2.56, matrix="pc.601" (and matrix="pc.709") enables you to do the RGB <-> YUV conversion while keeping the luma range, thus RGB [0,255] <-> YUV [0,255] (instead of the usual/default RGB [0,255] <-> YUV [16,235]).

All VirtualDub filters (loaded with LoadVirtualdubPlugin) support only RGB32 input.

If you try to use any of these filters with RGB input, you will get an error. Putting ConvertToYUY2 just before the offending filter should resolve the problem. All AviSynth filters support YUY2 input.

Conversion back and forth is not lossless, so use as few conversions as possible. If multiple conversions are necessary, use ConvertBackToYUY2() to convert back to YUY2, when you applied a YUY2->RGB conversion prior to that in your script. This will reduce color-blurring, but there are still some precision lost.

In most cases, the ConvertToRGB filter should not be necessary. If AviSynth's output is in YUY2 format and an application expects RGB, the system will use the installed YUY2 codec to make the conversion. However, if there's no installed YUY2 codec, or if (as is the case with ATI's YUY2 codec) the codec converts from YUY2 to RGB incorrectly, you can use Avisynth's built-in filter to convert instead.

Conversion paths

  • The ChromaInPlacement, chromaresample and ChromaOutPlacement options are only used in the 'planar conversion part' of the conversion path, and they process the chroma of the clip.

In v2.60 the following conversion paths occur

  • YUV planar -> RGB via YV24
  • YUV planar -> YUY2 via YV16 (except for YV12 and parameters ChromaInPlacement/chromaresample/ChromaOutPlacement not explicitly set", in that case there is a direct conversion from YV12 to YUY2)
  • RGB -> YUV planar via YV24
  • YUY2 -> YUV planar via YV16 (except for YV12 and parameters ChromaInPlacement/chromaresample/ChromaOutPlacement not explicitly set", in that case there is a direct conversion from YUY2 to YV12)

Suppose you have a YUY2 clip for example and you convert it to YV24. The YUY2 will be converted to YV16 first without applying ChromaInPlacement, chromaresample and ChromaOutPlacement. Then YV16 will be converted to YV24 while applying chromaresample. ChromaInPlacement and ChromaOutPlacement won't be used since YV12 is not involved.

Sampling

This page covers the sampling methods and color formats in more detail.

Color conversions

This page covers the color conversions, "YUV <-> RGB", in more detail.

Changelog

v2.60 Added ConvertToY8, ConvertToYV411, ConvertToYV16, ConvertToYV24, ChromaInPlacement, ChromaOutPlacement, chromaresample, matrix="AVERAGE".
v2.50 Added ConvertToYV12.
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