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| Question | Answer |
| What is the definition of image resolution? | No. of pixels per inch of an image |
| What's screen resolution? | Number of pixels the screen has, typically the number of pixels per row multiplied by the number of pixels per column |
| What are pixels | Are the smallest areas that could be referred to in an image, this area often holds a colour and a corresponding binary value. |
| Bitmaps vs Vectors? | Bitmap: Group of pixels placed in specific areas with a specific binary value representing its colour Vector Graphics: Images created using mathematics and geometric quantities, such as lines, curves etc. They are scalable and their values are stored mathematically. |
| Adv and Disadv of Bitmap graphics | Adv: -Bitmaps are better than vectors for photo editing -Bitmaps require less processing effort Disadv: -File size changes when scaling is done -Distort when scaled |
| Adv and Disadv of Vector graphics | Adv -Vectors require more processing efforts -Good for logo designs Disadv -File size does not change when scaled -Does not distort when scaled -Not good for photo editing |
| What is lossless compression | A non-destructive method Compresses file(s) without losing any data Example: Run Length Encoding (RLE) - identifies repeated data and stores it in a bank as a single datum with a repeated count |
| What is lossy compression | Compression that removes unnecessary data to reduce file size A destructive method e.g. .mp3, .jpeg |
| What is a typical image size calculation? | Image has height=1000, width=800 and has 16BPP. What is the file size? Image resolution: 1000x800=800000px since there are 800000px and each pix is 16 bit: 800000x16=12800000bits=1.6MB |
| What is a sound sample rate | Sample rate - measured in hertz, how many times a sound's analogue amplitude is measured (sampled) per second |
| What is a sound sample | Converting analogue sound into digital format for computers, turning sound waves into binary values by MEASURING THE AMPLITUDE of the sound at regular time intervals |
| What is sample resolution | Also known as bit depth, it's the no. of bits available encode/assigned to a sample. Higher resolution=smaller error quantization, therefore less sound distortion |
| What is the equation to work out the bit rate of a song? | bit rate = sample rate*sample resolution |
| What is interlaced | Method that splits each image into two fields, odd number fields and even number fields, therefore each frame will only display half an image. Denoted by letter "i", at some frame rate (e.g. 1080i) images will collectively form a video, commonly used for TV broadcasting |
| What is progressive capture and replay | Progressive video capture displays each image entirely on each frame, therefore the higher the frame rate, the smoother the movements and better video quality. A lot of videos found on YouTube and in cinemas are progressive. |
| The two types of video compression? | Spatial and Temporal |
| What is spatial compression? | Spatial compression is similar to image or sound compression in that it takes the repeated areas of a frame and group them together and assigning them with some code |
| What is temporal compression | Temporal compression looks at the video as a whole and reduces unnecessary, repeated frames and therefore making the entire video smaller in file size. |
| What is the multimedia Container format? | Multimedia Container Format (MCF) was a project initially intended to self suffice a user to video features all in one file (audio, subtitle, menus, languages etc.) and so without having to rely on third party services. The project was abandoned in 2004 and is succeeded by Matroska files (.mkv) which is an open, free video container format that stores common multimedia contents. |
| What is bit streaming? | Bit streaming refers to the act of delivering data from the owner to the client over a communication line and the client receiving it and experiencing it part by part before the entire file transfer is complete. Bits arrive in the same order as they are sent |
| What is live streaming | Live streaming is similar to on-demand streaming except the event is happening as it is being streamed. This will require some sort of capture/streaming source (e.g. a camera), an encoder, a media publisher and a content providing network. Cannot be paused. |
| Applications of live streaming and its drawbacks | online lectures, live viewing of sports, of concerts etc. Drawbacks include the need for bandwidth, CPU Power, which together result in latency. |
| Lossless and lossy file formats for images? | Lossless: .raw, .png, .bmp Lossy: .jpeg, .gif |
| Lossless and lossy file formats for media? | Lossless: .wav, .flac, .alac Lossy: .mp3, .mp4, .ogg |
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