Video and audio editing
Learn the core concepts and decision-making in Cambridge 9626 Topic 11, then practise recall, application and transfer with fictional scenarios.
Section Paper 2 · Practical · 2 hours 30 minutes · 90 marks · 50% AS / 25% A Level
Exam scope and assessment notes
This is original StudyForA teaching and fictional practice based on Cambridge syllabus outcomes, not copied syllabus text, an official question, a required software brand or a Cambridge mark scheme. Practical software tasks here are planning and reasoning exercises; StudyForA does not inspect files created in spreadsheet, database, graphics, audio/video or animation software, simulate the practical exam environment, award official marks or predict a grade. Follow the software and file-format requirements issued by your centre for your exam year.
Before you begin
- Check whether your route is AS Level (Topics 1–11) or full A Level (Topics 1–21).
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Before Topic 11: video and audio editing
What you will learn
- Edit video for audience and output: aspect ratio, trim/join, titles/captions/credits, transitions, stills, audio, speed, filters, colour and export/compression
- Compare MP4, AVI, MOV and WMV and select resolution for DVD, internet or mobile use
- Edit audio tracks, normalise and remove DC offset, adjust noise/effects and export appropriately
- Explain sampling rate, sampling resolution, file size, containers, lossy/lossless compression and quality trade-offs
Edit for a purpose and audience
A timeline places video, still images, titles and audio in sequence. Trim unwanted footage, join clips, use readable captions and credit sources. Aspect ratio and resolution should suit the display. Fades and transitions can clarify changes, but too many distract. Audio can be added, removed, balanced or edited. Preview the complete export because a project timeline is not the same as a finished file.
Format and compression change delivery
Higher resolution and sampling detail can improve quality but increase file size and bandwidth. Lossless compression preserves the original information; lossy compression discards some detail to reduce size. A container such as MP4 can hold encoded audio/video streams and metadata; it is not itself a compression method. Check format support, target device, playback quality, captions and audio synchronisation after export.
Sources for this lesson
Pause and explain
Which approach best demonstrates secure, reliable IT practice in video and audio editing?
Worked example
A two-minute tutorial must stream on phones over limited data. Recommend an export approach and two checks.
Show the worked solution
- Use a mobile-friendly aspect ratio and moderate resolution/bit rate.
- Apply compression suited to supported devices.
- Check readability, audio sync and quality on a real phone and slow connection.
Answer Export in a widely supported container such as MP4 using a suitable codec and resolution/bit rate that balances clarity with file size. Keep captions readable at phone size. Test playback and audio synchronisation on the target device and connection; check that compression has not made text or demonstrations too difficult to see.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A video looks sharp on a monitor but takes too long to load on mobile. Name two export changes and one quality trade-off.
Give me a hint
Reduce data demand while keeping the content legible.
Compare my reasoning
- Reduce resolution to match likely display size.
- Adjust bit rate/compression or create a mobile version.
- Test detail, text and motion after export.
Create a mobile export at a lower, still-adequate resolution and bit rate, using a supported compressed format. This reduces file size and loading time but may soften small text or fast motion. Test on actual mobile devices and retain a higher-quality master if needed.
Look for these in your work
- Makes targeted export changes
- Explains the trade-off
- Includes playback testing
An audio waveform is too quiet and has a DC offset. What does normalisation address, and what does offset removal address?
Give me a hint
One adjusts level; the other recentres the waveform around zero.
Compare my reasoning
- Describe the amplitude adjustment from normalisation.
- Describe correction of a constant offset.
- Listen for clipping/noise after processing.
Normalisation adjusts the signal level toward a chosen peak or loudness target. Removing DC offset recentres the waveform around zero when it is shifted. After both, listen for clipping, amplified background noise and unwanted changes; normalisation does not remove noise by itself.
Look for these in your work
- Distinguishes the two operations
- Explains their purpose
- Checks for side effects
A teacher reuses clips from several sources in a lesson video. What should the credits and export review cover?
Give me a hint
Think about attribution, readability, media output and rights.
Compare my reasoning
- Record accurate source details and permissions.
- Make credits and captions readable for the intended audience.
- Review format, resolution, audio, transitions and final duration.
Check that each reused clip has appropriate permission and accurate source attribution. Keep scrolling credits readable with suitable timing and blank lines, add captions where required, and ensure the audio is clear. Export in the requested format and review the whole video for aspect ratio, transitions, sync and compression artefacts.
Look for these in your work
- Addresses provenance
- Checks readability/accessibility
- Reviews the rendered output
Common mistakes
- Confusing a container with a codec
- Using maximum resolution for every audience
- Overusing transitions or making captions unreadable
What can you explain now?
A video looks sharp on a monitor but takes too long to load on mobile. Name two export changes and one quality trade-off.
Compare with the explanation
Create a mobile export at a lower, still-adequate resolution and bit rate, using a supported compressed format. This reduces file size and loading time but may soften small text or fast motion. Test on actual mobile devices and retain a higher-quality master if needed.
Reduce data demand while keeping the content legible.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Make it stick
How do lossy compression and a media container differ?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.