cropping: make DisplayWidth/DisplayHeight include cropped area
#947
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The primary motivation for this change is to ensure that Matroska files with `PixelCrop*` elements are displayed consistently, regardless of whether cropping is applied. This makes such files compatible across software that either supports or ignores these elements. Without this change, files suffer from limited compatibility, whereas cropping tags should enhance the experience rather than be a requirement for proper image display. A secondary motivation is that an overwhelming number of files in the wild do not actually adjust the `DisplayWidth`/`DisplayHeight` elements as expected by the specification. Most of the time, these values are left uncropped, with the expectation that cropping will be applied later. This issue arises partly because MKVToolNix does not automatically perform this calculation, it only sets the `PixelCrop*` elements unless explicitly instructed by the user. Observing the existing files in circulation, it is evident that almost no one manually adjusts these values. Lastly, some subtitle formats depend on the video size for positioning and rendering, making them sensitive to cropping. Currently, most authoring tools do not take cropping into account. By making the Matroska specification more flexible and allowing subtitles to be cropped along with the video, it becomes easier to produce files that are compatible with various Matroska players. For a more detailed discussion on this topic, please refer to the links below: See: https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389 See: mpv-player/mpv#13446
kasper93
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Feb 26, 2025
I don't expect the Matroska specification to be adjusted for this to work soon, so in the meantime, follow the spec as written and add an option to support most files in the wild. I would prefer this to never be an option, but it looks like it's unavoidable. Recently, FFmpeg added cropping support for Matroska, so we don’t want to be the odd one out by doing it differently... See for more details: ietf-wg-cellar/matroska-specification#947 https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389 mpv-player#13446 Fixes: mpv-player#15800
kasper93
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Mar 3, 2025
I don't expect the Matroska specification to be adjusted for this to work soon, so in the meantime, follow the spec as written and add an option to support most files in the wild. I would prefer this to never be an option, but it looks like it's unavoidable. Recently, FFmpeg added cropping support for Matroska, so we don’t want to be the odd one out by doing it differently... See for more details: ietf-wg-cellar/matroska-specification#947 https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389 mpv-player#13446 Fixes: mpv-player#15800
kasper93
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Mar 4, 2025
I don't expect the Matroska specification to be adjusted for this to work soon, so in the meantime, follow the spec as written and add an option to support most files in the wild. I would prefer this to never be an option, but it looks like it's unavoidable. Recently, FFmpeg added cropping support for Matroska, so we don’t want to be the odd one out by doing it differently... See for more details: ietf-wg-cellar/matroska-specification#947 https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389 #13446 Fixes: #15800
HopperLogger
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Mar 26, 2025
I don't expect the Matroska specification to be adjusted for this to work soon, so in the meantime, follow the spec as written and add an option to support most files in the wild. I would prefer this to never be an option, but it looks like it's unavoidable. Recently, FFmpeg added cropping support for Matroska, so we don’t want to be the odd one out by doing it differently... See for more details: ietf-wg-cellar/matroska-specification#947 https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389 mpv-player#13446 Fixes: mpv-player#15800
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The primary motivation for this change is to ensure that Matroska files with
PixelCrop*elements are displayed consistently, regardless of whether cropping is applied. This makes such files compatible across software that either supports or ignores these elements. Without this change, files suffer from limited compatibility, whereas cropping tags should enhance the experience rather than be a requirement for proper image display.A secondary motivation is that an overwhelming number of files in the wild do not actually adjust the
DisplayWidth/DisplayHeightelements as expected by the specification. Most of the time, these values are left uncropped, with the expectation that cropping will be applied later. This issue arises partly because MKVToolNix does not automatically perform this calculation, it only sets thePixelCrop*elements unless explicitly instructed by the user. Observing the existing files in circulation, it is evident that almost no one manually adjusts these values.Lastly, some subtitle formats depend on the video size for positioning and rendering, making them sensitive to cropping. Currently, most authoring tools do not take cropping into account. By making the Matroska specification more flexible and allowing subtitles to be cropped along with the video, it becomes easier to produce files that are compatible with various Matroska players.
For a more detailed discussion on this topic, please refer to the links below:
See: https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2389
See: mpv-player/mpv#13446