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PostOnce downloads the best version of your video that the source platform provides, then adjusts it only when a destination requires it.

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The video looks lower quality

  • The source stores it at low quality. Instagram often keeps older videos at low resolution, so reposting old Instagram videos can look soft. Turn on Skip low-quality videos in the workflow’s Settings › Source and choose a minimum (360p to 1080p) to leave them out.
  • The destination compresses it. Every platform re-compresses uploads. PostOnce re-encodes only when a platform needs it: for example, Instagram videos larger than 300 MB or wider than 1920 pixels are resized, and X videos may be converted to 720p.
  • The video is too large for the destination. Very large files are compressed to fit. To keep the best quality, upload files under the platform’s limit (see Platforms at a glance).

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The video has no sound

PostOnce only copies a silent video when the original is confirmed silent. Otherwise it keeps trying to get the version with sound, and fails the post if it can’t, rather than publishing it silent.
  • TikTok photo slideshows get music added by TikTok automatically when PostOnce publishes them. Their original TikTok music isn’t available to other apps, so on other platforms they post as images.
  • TikTok videos whose sound TikTok muted (for copyright) are imported without that sound.

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There are black bars around the video

Some platforms reject videos of certain shapes. Instead of failing the post, PostOnce adds bars rather than cropping:
  • Facebook Reels that are much taller than 9:16 or wider than 2:1 get side or top bars.
  • Facebook and Instagram Stories are fitted to 9:16.
  • TikTok videos are fitted to vertical when they need re-encoding.
For the cleanest result, use 9:16 vertical videos for TikTok, Reels, Shorts and Stories.

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The cover or thumbnail is different

  • TikTok: Keep thumbnail consistent on TikTok (on by default, under the workflow’s Settings › Destinations) adds the source video’s cover as the first frame, so the TikTok cover matches. Turn it off to let TikTok choose.
  • YouTube: PostOnce uploads the source thumbnail. If YouTube rejects it, the video keeps YouTube’s automatic thumbnail.
  • Pinterest: PostOnce creates a cover image for video Pins.

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Add an intro or outro

Under Settings › Content, add an Intro video or Outro video to every copied video. Each clip can be MP4, MOV or WebM, up to 15 seconds and 50 MB. It’s added to videos for TikTok, Instagram, YouTube, Facebook, X, Threads, Bluesky and Pinterest.

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Still stuck?

Search this help center with ⌘ K, or email support@postonce.to from the address you use for PostOnce. Include the platform, the approximate time, and the exact message you saw. Never send passwords, access tokens, API keys, or card details. Something missing from PostOnce? Request a feature or check the roadmap.
Last modified on October 7, 2026