diff --git a/css/css.css b/css/css.css index 03046d8..26f4e9e 100644 --- a/css/css.css +++ b/css/css.css @@ -80,3 +80,11 @@ div { background-color: #f9f2f4; border-radius: 4px } + +.beware { + font-size: 150%; +} + +.footnote { + font-size: 90%; +} diff --git a/img/colourspace_metadata_mediainfo.png b/img/colourspace_metadata_mediainfo.png new file mode 100644 index 0000000..b8891ca Binary files /dev/null and b/img/colourspace_metadata_mediainfo.png differ diff --git a/index.html b/index.html index 0b02461..8bd4261 100644 --- a/index.html +++ b/index.html @@ -493,18 +493,50 @@

Transcode video to a different colourspace

-

This command applies a filter to convert the video to a different colour space.

+

This command uses a filter to convert the video to a different colour space.

ffmpeg -i input_file -c:v libx264 -vf colormatrix=src:dst output_file

ffmpeg
starts the command
-i input file
path, name and extension of the input file
-c:v libx264
tells ffmpeg to encode the video stream as H.264
-vf colormatrix=src:dst
the video filter colormatrix will be applied, with the given source and destination colourspaces.
- Accepted values include bt601 (Rec.601), smpte170m (Rec.601, 525-line/NTSC version), bt470bg (Rec.601, 625-line/PAL version), bt709 (Rec.709), and bt2020 (Rec.2020).
+ Accepted values include bt601 (Rec.601), smpte170m (Rec.601, 525-line/NTSC version), bt470bg (Rec.601, 625-line/PAL version), bt709 (Rec.709), and bt2020 (Rec.2020).
For example, to convert from Rec.601 to Rec.709, you would use -vf colormatrix=bt601:bt709.
output file
path, name and extension of the output file

Note: Converting between colourspaces with ffmpeg can be done via either the colormatrix or colorspace filters, with colorspace allowing finer control (individual setting of colourspace, transfer characteristics, primaries, range, pixel format, etc). See this entry on the ffmpeg wiki, and the ffmpeg documentation for colormatrix and colorspace.

+
+

Convert colourspace and embed colourspace metadata

+

ffmpeg -i input_file -c:v libx264 -vf colormatrix=src:dst -color_primaries val -color_trc val -colorspace val output_file

+
+
ffmpeg
starts the command
+
-i input file
path, name and extension of the input file
+
-c:v libx264
encode video as H.264
+
-vf colormatrix=src:dst
the video filter colormatrix will be applied, with the given source and destination colourspaces.
+
-color_primaries val
tags video with the given colour primaries.
+ Accepted values include smpte170m (Rec.601, 525-line/NTSC version), bt470bg (Rec.601, 625-line/PAL version), bt709 (Rec.709), and bt2020 (Rec.2020). +
-color_trc val
tags video with the given transfer characteristics (gamma).
+ Accepted values include smpte170m (Rec.601, 525-line/NTSC version), gamma28 (Rec.601, 625-line/PAL version)1, bt709 (Rec.709), bt2020_10 (Rec.2020 10-bit), and bt2020_12 (Rec.2020 12-bit).
+
-colorspace val
tags video as being in the given colourspace.
+ Accepted values include smpte170m (Rec.601, 525-line/NTSC version), bt470bg (Rec.601, 625-line/PAL version), bt709 (Rec.709), bt2020_cl (Rec.2020 constant luminance), and bt2020_ncl (Rec.2020 non-constant luminance).
+
output file
path, name and extension of the output file
+
+
Examples
+

To Rec.601 (525-line/NTSC):

+

ffmpeg -i input_file -c:v libx264 -vf colormatrix=bt709:smpte170m -color_primaries smpte170m -color_trc smpte170m -colorspace smpte170m output_file

+

To Rec.601 (625-line/PAL):

+

ffmpeg -i input_file -c:v libx264 -vf colormatrix=bt709:bt470bg -color_primaries bt470bg -color_trc gamma28 -colorspace bt470bg output_file

+

To Rec.709:

+

ffmpeg -i input_file -c:v libx264 -vf colormatrix=bt601:bt709 -color_primaries bt709 -color_trc bt709 -colorspace bt709 output_file

+

MediaInfo output examples:

+ MediaInfo screenshots of colourspace metadata
+

⚠ Using this command it is possible to add Rec.709 tags to a file that is actually Rec.601 (etc), so apply with caution!

+

These commands are relevant for H.264 and H.265 videos, encoded with libx264 and libx265 respectively.

+

Note: If you wish to embed colourspace metadata without changing to another colourspace, omit -vf colormatrix=src:dst. However, since it is libx264/libx265 that writes the metadata, it's not possible to add these tags without reencoding the video stream.

+

For all possible values for -color_primaries, -color_trc, and -colorspace, see the ffmpeg documentation on codec options.

+
+

1. Out of step with the regular pattern, -color-trc doesn't accept bt470bg; it is instead here referred to directly as gamma.
+ In the Rec.601 standard, 525-line/NTSC and 625-line/PAL video have assumed gammas of 2.2 and 2.8 respectively. ↩