Information processes in multimedia systems for HSC Information Processes and Technology
“Describe how the information processes are carried out in multimedia systems, including capturing and digitising media, authoring, compression, storage and delivery”
Collecting captures media by digitising it: scanners and cameras for images, microphones for audio, video cameras for video, with sampling and resolution settings that fix quality. Organising and processing happen in authoring software, where the media are assembled, edited and linked into an interactive product with navigation. Compression reduces file sizes so the media can be stored and delivered practically, using lossless methods that lose nothing and lossy methods that discard detail people barely notice. Storing and retrieving keep the assets and the finished product, and transmitting and displaying deliver it to users on disc, over the web or by streaming.
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What this dot point is asking
NESA wants you to describe how the seven information processes are carried out when a multimedia system is created and delivered: capturing and digitising the media (collecting), assembling it into an interactive product (authoring, which spans organising and processing), reducing file sizes (compression), and storing and delivering it to users. This applies the characteristics of multimedia to the process framework.
The answer
Collecting: capturing and digitising
Media enters the system by being digitised. Images are captured with scanners or digital cameras; audio with microphones and sound cards that sample the wave; video with cameras that record sequences of frames. Existing media can also be imported. The capture settings, resolution for images, sample rate and size for audio, frame rate for video, fix the quality and the file size from the start, so getting them right at capture is important because quality lost here cannot be recovered later.
Organising and processing: authoring
Authoring is where the captured media are assembled into the finished multimedia product. Authoring software lets the developer arrange media on a timeline or in screens, edit it (crop images, trim audio, adjust video), and add the navigation, buttons and hyperlinks that make it interactive. This combines the organising process (structuring the content and its links) with the processing process (editing and transforming the media). The author defines how the user will move through the product.
Compression
Raw multimedia files, especially audio and video, are huge, so compression reduces their size for storage and delivery. Lossless compression reduces size without discarding any data, so the file restores exactly; it suits text and images where every detail matters but gives modest size reductions. Lossy compression discards detail the human eye or ear is unlikely to notice, achieving much larger reductions; it is used for photographs, music and video where some loss is acceptable. Choosing the type and degree of compression trades quality against size and download or streaming speed.
Lossy and lossless compression serve different needs. Lossless restores the file exactly and suits text and line art but compresses little; lossy discards detail people barely notice and compresses far more, which is why photos, music and video almost always use it.
Storing and retrieving
The system stores both the source media assets and the finished product. Assets are retrieved and reused across projects, and the completed multimedia product is stored ready for delivery. Because multimedia files are large, storage capacity and organisation matter, and the move from optical disc to large drives and cloud storage has shaped what is possible.
Transmitting and displaying: delivery
Delivery is how the finished product reaches the user. It may be distributed physically, downloaded as a file, or streamed over the internet so it plays as it arrives without a full download first. Streaming depends on bandwidth: enough is needed to deliver the compressed media fast enough to play smoothly. Displaying then presents the media through screens, speakers and the interactive interface the author built.
Tying the processes together
The pipeline runs capture, author, compress, store, deliver and display. A decision early, such as capture resolution or compression level, ripples through the whole chain to the user's final experience, which is why the processes must be considered together rather than in isolation.
Confusing capturing with authoring. Capturing digitises individual media; authoring assembles and links them into the interactive product.
Mixing up lossy and lossless. Lossless restores the file exactly but compresses little; lossy discards unnoticed detail for much greater reduction. Match the type to the media.
Saying quality lost at capture can be fixed later. Detail not captured (low resolution, low sample rate) cannot be added back; capture settings set the ceiling.
Ignoring bandwidth in delivery. Streaming needs enough bandwidth to play the compressed media smoothly; this is why compression and delivery are linked.
Forgetting interactivity in authoring. Adding navigation, buttons and hyperlinks is part of authoring, not an afterthought; it is what makes the product multimedia.
Exam-style questions
Questions in the style of NESA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
2020 HSC-style3 marksCompare TWO techniques that can be used to compress image files.Show worked answer →
"Compare" at 3 marks needs two techniques with similarities and differences.
Lossy compression (for example JPEG): permanently discards image data that the eye is least likely to notice. It achieves much smaller file sizes, but quality is reduced and the discarded data cannot be recovered. Best for photographs where small quality loss is acceptable.
Lossless compression (for example PNG or GIF using run-length/dictionary encoding): reduces size by storing data more efficiently (for example recording runs of identical pixels) without discarding any information, so the original image is fully restored on decompression. File savings are smaller, but quality is preserved. Best for graphics with large flat areas or where exact detail matters.
Comparison: both reduce file size for storage and faster transmission, but lossy trades quality for greater compression and is irreversible, whereas lossless keeps full quality but compresses less. Markers reward naming two techniques and contrasting their size/quality trade-offs.
2019 HSC-style6 marksA producer is developing a multimedia presentation about holiday destinations to be uploaded to the internet, integrating images, animation, audio and video. Recommend and justify appropriate file formats for images, animation, audio and video in this multimedia presentation.Show worked answer →
For 6 marks recommend a format for each of the four media types and justify each choice for a web presentation.
Images: JPEG for photographs of destinations - lossy compression gives small files that download quickly over the web while keeping acceptable photographic quality. (PNG is justified where transparency or sharp graphics are needed.)
Animation: animated GIF for simple short loops, or HTML5/MP4 for richer animation - chosen because they are widely supported in browsers and keep file size manageable for streaming over the internet.
Audio: MP3 - lossy compression produces small files with good quality and near-universal browser/device support, ideal for narration or background music delivered online.
Video: MP4 (H.264) - efficient compression gives good quality at small sizes and is supported across browsers and devices, so clips stream smoothly.
Justify each by web suitability: small size for fast download/streaming, broad compatibility, and quality acceptable for the purpose. Markers reward a sensible format for all four media types each with a reason tied to internet delivery.
2020 HSC-style3 marksDistinguish between morphing and distorting. Include an example of each.Show worked answer →
"Distinguish" at 3 marks needs the difference plus an example of each.
Morphing: a technique that gradually transforms one image into a completely different image through a smooth series of in-between frames, so one object appears to change into another. Example: a face slowly morphing into the face of a different person in a music video.
Distorting: altering the shape or appearance of a single image by stretching, twisting, bending or warping parts of it, while it remains the same object. Example: stretching a photo of a face to exaggerate the nose, or bending text along a curve.
The key distinction: morphing blends between two different images over time, while distorting reshapes one image. Markers reward the change-into-another versus reshape-the-same contrast plus a valid example of each.