I’ve run into a consistent playback problem with certain DVD rips of the Step by Step complete series (7 seasons) on the Plex Roku client. Here’s the technical breakdown:
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Many DVDs have 4:3 content encoded inside a 16:9 frame (pillarboxed with black bars on the sides).
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These videos were ripped with MakeMKV so that individual episodes could be easily added to Plex.
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When remuxed into MKV containers:
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The container’s Display Aspect Ratio (DAR) and Pixel Aspect Ratio (SAR) can be set to indicate 16:9 correctly.
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VLC and Plex Web clients respect the container’s DAR/SAR, so the video displays correctly.
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Problem on Roku Plex client:
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The Plex Roku app ignores the MKV container’s DAR/SAR entirely.
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It only reads the DAR/SAR flags inside the MPEG-2 video stream itself.
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If the MPEG-2 stream has a 4:3 DAR/SAR (even though the pixels are already 16:9 with black bars), Roku will stretch the video incorrectly, resulting in a horizontally squashed image. (The image is not squashed when playing the video in VLC or when playing with the PLEX web client.)
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Season breakdown for Step by Step DVDs:
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Seasons 1–2: Widescreen (16:9) container with 4:3 content, SAR/DAR mostly correct, Plex Roku displays fine (with one exception that required a display width fix).
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Season 3, 5, 6, 7: Widescreen (16:9) container with 4:3 content, but MPEG-2 SAR/DAR flags are set to 4:3 → causes Roku Plex to squash the video horizontally.
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Season 4: The “correct” authoring — 4:3 container with 4:3 content, no black bars, displays correctly everywhere.
So while there were definitely issues with the way the DVDs were authored, VLC and PLEX web client seemed to have no issues and played the videos without squashing the video, while the PLEX Roku client squashed the video.
