An independent film studio sells its films on discs. It also offers the same films as downloads. The studio is deciding whether to keep selling films on optical discs.
Discuss the use of optical storage for selling films.
Your answer should include:
- how data is stored on optical media
- the benefits of optical discs for selling films
- the drawbacks of optical discs for selling films.
You do not need to consider other types of secondary storage.
Mark scheme
Indicative content
How data is stored on optical media
- Data is stored as pits and lands burnt or pressed into a spiral track on the disc.
- A laser beam is shone at the disc and the light that is reflected back is measured; pits and lands reflect the light differently.
- The differences in the reflected light are read as binary 1s and 0s.
Benefits of optical discs for selling films
- Optical discs are cheap to mass produce once the master disc has been pressed, so the studio can sell each film at a low price.
- A disc is small and light, so a customer can easily store it, carry it home or give it as a gift.
- A Blu-ray disc can hold a whole high-definition film (up to 50 GB), so a customer can watch the film without an internet connection.
- Artwork can be printed on the disc and its case, which helps the studio sell the film.
Drawbacks of optical discs for selling films
- A DVD holds only about 8.4 GB, so a high-definition film with extra features may not fit on one and the studio would need to sell it on a Blu-ray instead.
- Optical discs are easily scratched, which can cause read errors so the film will not play.
- Many modern devices, such as some laptops, no longer have a disc drive, so some customers would not be able to play the film.
- Discs can be affected by heat and sunlight, so they may deteriorate over time.
Levels
- Level 0 (0 marks): No rewardable content.
- Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
- Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
- Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)
Additional guidance
- Level 2 requires points to be linked or developed, for example a benefit or drawback explained in terms of the studio or its customers. An answer that only lists basic, independent points, with no linkage, is limited to Level 1.
- Level 3 requires all three areas and a judgement about whether the studio should keep selling films on optical discs. Do not credit magnetic storage or solid state storage as a description of how optical media stores data; credit these only where they are compared with optical media.
Example answers and how they were marked
Optical media stores data as pits and lands burnt into a spiral track. A laser beam is shone at the disc and the reflected light is measured; pits and lands reflect it differently, and this pattern is read as binary 1s and 0s. Optical discs are cheap to mass produce, so the studio can sell each film at a low price, and a disc is small and light so a customer can store it or give it as a gift. A Blu-ray holds a whole high-definition film and can be played without an internet connection. However, a DVD may not hold a high-definition film with extra features, so the studio would need a Blu-ray, and discs are easily scratched, which can cause read errors so the film will not play. Many modern laptops have no disc drive, so some customers could not play the film. Overall the studio should keep selling discs as well as downloads, because the discs are cheap to produce and give customers a copy that works without an internet connection, even though some customers will prefer to download.
Why: Explains how data is stored on optical media using pits, lands, reflected light and binary (AO1); gives benefits applied to selling films (cheap mass production, portability, Blu-ray holds a film and plays offline) and drawbacks (DVD capacity, scratches causing read errors, no disc drive in modern laptops); ends with a sustained judgement and recommendation, so it meets the Level 3 guidance.
Optical storage uses a laser to read pits and lands. It is cheap to make discs, so the studio can sell them cheaply. Discs are portable. But they can be scratched and damaged. Some computers don't have a disc drive.
Why: Basic point about how data is stored, a laser reading pits and lands (1), plus basic points about benefits (cheap to produce, portable) and drawbacks (scratched, no disc drive), but the points are independent and undeveloped with no linkage or application to the studio, so it is the top of Level 1: 2 marks.
Optical storage uses magnets to store data. The film studio should use optical discs because they are very fast and have a large capacity. They are not affected by scratches.
Why: No creditworthy points. Confuses optical storage with magnetic storage; claims it is fast, has a large capacity and is not affected by scratches, all of which are incorrect. Level 0.