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Colorspace

Colorspace(--colorspace) option allows you to specify the YUV colorspace and color_range (Dynamic Range) of the output video

Colorspace
unspecified Do Nothing. It works the same as the older iw3 version.
auto Use the same colorspace and color_range as the input video.
bt709 Use bt709 for colorspace. color_range will be the same as the input video.
bt709-pc BT.709 Full Range
bt709-tv BT.709 Limited Range
bt601* BT.601 version of bt709*

Difference between unspecified and other options

unspecified

When unspecified is specified, the stereo generation process (expecting full range input) is performed without converting the dynamic range of the frame images, even if the video is limited range.

This can cause color changes and banding artifact.

option other than unspecified

When an option other than unspecified is specified, the frame image is converted to full range before stereo generation processing is performed. And if the output is limited range, it is re-converted from full range to limited range when video encoding.

This is a more correct process than unspecified. However, if the colorspace and color_range of the input video are unknown or have undefined values, the color conversion may not be correct or may result in an error.

Relationship between Colorspace and Pixel Format

When rgb24 is specified for Pixel Format, the behavior is the same as the unspecified case, no matter what Colorspace is specified.

When yuv420p or yuv444p is specified for Pixel Format and the output color_range is full range(tv), yuvj420p or yuvj444p will be used instead.

Case where colorspace of the input video is unknown

If the input video is smaller than 720p, BT.601 is used, otherwise BT.709 is used.

Cases where color_range of the input video is unknown

Determines color_range from pix_fmt. yuv4* is limited range(tv), yuvj4*, rgb*, gbr* is full range(pc).

If none of the above, leave unknown (unspecified).

Cases where colorspace or color_range of the input video is still unknown

If only one of the two is unknown, the conversion is performed using the (forced)guessed value. If both are unknown, it works the same as if unspecified is specified.

tv -> pc, pc -> tv conversion

The dynamic range changes between the input video and the output video, so the colors will change.

Export / Export Disparity

unspecified

Outputs frame images without converting dynamic range. The dynamic range of the frame image also differs depending on whether the input video is limited range(tv) or full range(pc).

option other than unspecified

Outputs frame images converted to full range. If the video is limited range, the color will change on the frame image. If the video is encoded to limited range on import, the color of the final video will not change.

Import (yml input)

Case exported with options other than unspecified

If exported specifying other than unspecified, source_color_range andoutput_colorspace fileds are added to the yml file.

source_color_range is the dynamic range of the input video (1: MPEG Limited Range, 2: JPEG Full Range). output_colorspace is the color space (1: BT.709, 5: BT.601) in YUV of the frame image. Note that source_color_range is the dynamic range of the source video, not the dynamic range of the frame image. The frame image is always full range in this case. This fields are used in auto or colorspace and color_range conversions during import.

Case where source_color_range,output_colorspace does not exist in yml file

The reason for the missing source_color_range,output_colorspace in the yml file is one of the following.

  • Exported with an older iw3 version
  • Exported with Colorspace=unspecified
  • Both colorspace and color_range of the input video were unknown

If source_color_range and output_colorspace are missing in the yml file, the frame image is assumed to be the same as colorspace and color_range specified by Colorspace.

For example,

  • When bt709-tv is specified, the frame image is processed as BT.709 Limited Range to rgb24 conversion result.
  • When bt709-pc is specified, the frame image is processed as BT.709 Full Range to rgb24 conversion result.