Media Compression

 What is media compression? It is when we discard information from an image or video in order to reduce the file size. To summarise.....higher compression rate- lower quality and vice versa. 

All videos are a combination of images or audio. Within a video, 25 to 30 frames are displayed in a single second of video known as frame-rate. More frames mean a higher quality however more frames mean a bigger file size. Large files take up quite a lot of space and internet bandwidth. But how do we make a file smaller? We do this by lowering the fps rate, colour and sound. 

Spatial compression known as an intraframe is applied to individual frames. JPEG is an example of this, JPEG is a created colour info of the image. When reduced it's known as chroma subsampling. Images are split into sections of 8x8 pixels known as macroblocks. MPEG is more complicated. 

When compressing a video we have to think about bitrate. Bitrate is the amount of data or bits that are being used every second. If a video has a low bitrate it will be low resolution/quality . 

But what are the best quality.......in a video shown to us we see that 60hz or 60fps is the best quality. Its quality is remarkable and can capture every bit. There is no delays or lag. The worst quality is 8hz or 8fps it's slow and not clear compared to the 60hz. You can see a very clear difference between the two. 

With how video compression is used it is the same with audio compression. In the third video, we noticed the audio compression differences. With MP3 and M4 there wasn't necessarily a huge sound difference, if you listened by ear you wouldn't notice the difference. However, a lower quality MP3 has a loss of info in it and brings a more fuzzy sound and isn't clear with 64kbps. 

But to go more in-depth with audio compression there are two types, lossy and lossless. Most compression is lossy as it has info removed or lost which retains the quality. Lossless compression is used in cases where all info is important and nothing has really changed. 

In video 4 we learned about the different BIT rates. BIT is a binary digit for storage and is the smallest unit of data. 1000 bytes is equivalent to 1 kilobyte and 1024 kilobytes equals 1 megabyte and that continues on. 

- Kate O Toole 

                                                            Sources

Video compression: https://youtu.be/qbGQBT2Vwvc

Difference in framerate: https://youtu.be/2Ds7EcJ2Ia4

What you lose when you compress music: https://youtu.be/MmecPiKClHk

Video formats, codecs and containers: https://youtu.be/XvoW-bwIeyY

Image citation: https://plexxie.com/question/61/what-is-an-audio-compression

Computer skills: Bits, bytes, kilobytes, megabytes, gigabytes, terabytes: https://youtu.be/u4P0LOofEFs