Web Deployment Checklist: Release and Roll Back a Course App

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Practical Web Development — Lesson 10 of 10 · Senior A successful deployment command does not prove a course application works. A release is complete when important user journeys work in the target environment and the team can recognize and recover from a bad change. This lesson turns a small course app into a practical release exercise with explicit acceptance and rollback criteria. Describe the change and its risk Suppose a release adds saved course shortlists. Separate the new browser interface, the server endpoint and any database change. Identify what happens when old browser code talks to the new server, and when the previous server version reads newly written data. Rolling back code is not the same as reversing a data migration. Write a short release record before deploying. Use real commit and build identifiers in your own project; the values below are placeholders for the exercise. Change: Add saved course shortlists Build: <immutable build identifier> Owner: <person ...
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Video in Multimedia: Formats, Compression and Captions

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Video in multimedia combines a sequence of images with optional sound to show movement, demonstrations and stories. For a web lesson, the practical choices are the file format, compression, dimensions and accessible playback. Start with what the learner must see, then choose the smallest file that preserves those details.

Analog and digital video

Analog video represents pictures through a continuously varying signal. Digital video stores encoded image and audio data that software can edit, transmit and play. A phone recording is a useful starting point for a short lesson: record a clear demonstration, remove unnecessary footage and export a copy for web delivery.

Container vs codec

A container packages video, audio and metadata into a file. A codec encodes and decodes a media stream. MP4 and WebM are examples of containers; the file extension alone does not tell you which codec is inside. Check the actual container and codecs when a file fails to play. See MDN’s media container guide.

Compression and readable demonstrations

Compression reduces the data needed to store or transmit video. Export settings affect both file size and visible quality. A slide with small text may become unreadable after aggressive compression even when a talking-head clip still looks acceptable. Keep an original master and test a compressed copy before publishing.

  • Dimensions: choose a resolution that keeps the important details legible.
  • Bitrate: compare file size and quality using the same short sample.
  • Frame rate: use a rate suitable for the movement in the demonstration.
  • Aspect ratio: avoid stretching or cropping essential content.

To estimate download size, multiply the combined average bitrate by duration and divide by eight. A 60-second clip at 2 megabits per second is roughly 15 megabytes, excluding container overhead. This is an estimate; inspect the exported file for its actual size.

Historical television terminology

NTSC, PAL and SECAM describe legacy analog television systems. HDTV describes high-definition television and is not another analog color system. These terms may matter when digitizing old recordings; they are not a list of browser video file formats.

Historical diagram comparing VGA and HDTV aspect ratios

The historical diagram above compares display shapes. It should not be used as a browser codec compatibility chart.

Captions and player controls

Provide controls for playing, pausing and adjusting sound. Avoid forcing autoplay. Captions should include speech and meaningful sounds; a transcript gives readers a text version of the explanation. When a visual action carries essential information, explain it in narration or an accompanying description. Test the lesson with the audio muted and with keyboard controls.

Practice: make a useful web video

Record a short demonstration with one learning goal. Show the steps in order, add accurate captions, and provide a text summary. Keep player controls available and avoid autoplay. Test whether the lesson can still be understood when the audio is muted or the video cannot load.

Related lessons

Multimedia course guide and reading path · Build an HTML audio and video lesson · Build a semantic HTML course page

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