Keep the original vertical framing of YouTube Shorts
Some Shorts are delivered as separate adaptive video and audio representations, so the service may need to combine those tracks into one downloadable MP4 or WebM. The final container and codecs determine playback support; H.264/AAC MP4 is widely recognized on phones, while VP9 or AV1 support varies. No watermark is added by this workflow, but an existing watermark embedded in the creator's video remains part of the source. Check the format list for portrait resolution and allow larger 1080p files time to transfer over mobile connections.
Shorts are designed for portrait screens, but their actual dimensions and frame rates depend on each creator's upload and the formats YouTube publishes. A common Full HD portrait frame is 1080 by 1920 pixels with a 9:16 aspect ratio. YTMetadata reads the available source tracks and offers real resolutions rather than cropping a landscape video or stretching a lower-resolution file. The selected output retains the source's encoded picture, frame rate, and audio when the available streams can be muxed without re-encoding.