at://

Video Handling

Handling video uploads and processing

Video uploads

Video uploads differ slightly from image uploads, since they are typically much larger files and have a significantly long processing time. Individual Atmosphere apps or CDNs may impose additional limits on video uploads.

For this reason, video uploads are typically handled by a side-car service before the final file(s) are uploaded to the PDS as blobs. For example, Bluesky has the https://video.bsky.app service for handling the upload and transcoding of videos before they are written to the PDS as a blob.

Aspect ratios

Depending on the requirements of your application, you may need to supply an aspect ratio along with video uploads. This metadata can be tricky to compute. If you're developing in a browser, you can load the video into a <video> and observe the dimensions when loaded. If you're in a native app, you'll most likely be able to get it via the media picker APIs. Alternatively, you can use a tool like ffprobe :

import { ffprobe } from "https://deno.land/x/fast_forward@0.1.6/ffprobe.ts";

export async function getAspectRatio(fileName: string) {
  const { streams } = await ffprobe(fileName, {});
  const videoSteam = streams.find((stream) => stream.codec_type === "video");
  return {
    width: videoSteam.width,
    height: videoSteam.height,
  };
}

Transcoding

Videos will need time to transcode using a tool like ffmpeg on the server side before they are available from the firehose. This can lead to UX gaps — if a video blob is accompanying a new post, the video service only knows about the video once the post appears in the firehose. This means that people will be able to see the post before processing is complete, which will show a missing video for several seconds.

It is possible to design an application endpoint to allow submitting videos to a separate microservice for processing before creating a post. This method also allows for better UX, since you can show the processing state to the user and let them know if the processing job fails.

There are client-side code samples for both methods here:

Further Reading and Resources