Course Module - BAFI101 Practical Screen-craft Lecture - Stu Bailey
Researching different CODEC's, Bitrates, Chroma-sampling and what they do?
What does CODEC stand for?
A device or program which is capable of performing transformations on a data stream or a signal.
Compression and Decompression
What is a CODEC used for?
Codec is a software that is used to compress or decompress a form of a digital media file, a few examples of this would include a song or a video file. Programs such as windows media player and other programs actually use these codecs to play and create digital media files. A codec can consist of two components, known as an encoder or decoder.
An encoder which can be a device, circuit, transducer, software programme that converts information from one format or code to another for the purposes of standardization, speed, secrecy, security or compressions.
A decoder is a circuit that changes a code into a set of signals, it does the reverse of encoder, they are simpler to design.
At which point of the production workflow is a codec used?
A codec is the word given to describe the order used to layout data of an audio or video file, it may be used for playback, editing or changing to other codecs (known as transcoding). Codecs are used to organise media data but that data is held within something known as a container. There are many different types of audio and video codecs and they have their own advantages. Premiere will need a codec to analyse the files but then you would need to choose a codec to place the files, so it would be used at the beginning and end of post production.
What is the difference between a Codec and a container? What they contain?
Codec is a method used for encoding and decoding data, more specifically for compressing data.
Container is what holds the grouping of compressed video, a container can be referred to as a format, the container will take care of the packing, transport and presentation. An example of this i.e. MPEG 4 file is represented by a .mp4 file type.
What is chroma-subsampling and how does it affect an image
Chroma sampling is the name given to a practice of encoding images by giving the images less resolution, in doing so it can reduce the file size, but the whole process can be sensitive to any variations within the brightness, changing colour. Has an effect on adding harsh lines, no visual difference which can be perceived by the person viewing the photograph but it can saturate the colours to form significant artifacts.
What is meant by Bitrate?
How much information is being analysed at any given point.
What CODEC(s) do you think you should be using and why?
H.264 .MP4 - Very good for it's compression, you can create a lot of information with a lot of space to compress files, making the file size smaller but this would be used for if you wanted to put your video online, website or Vimeo for people to watch, this CODEC wouldn't apply to broadcast quality as it makes the quality look flack and degrades.
References
Matt Laufer (2014) The Difference Between Codec's and Containers , Available at:http://www.encoding.com/blog/2014/01/13/whats-difference-codecs-containers/(Accessed: 24th November 2015).
Margaret Rouse (2005) Bit Rate Definition , Available at:http://searchnetworking.techtarget.com/definition/bit-rate (Accessed: 24th November 2015).
Matthews (Not Posted a year) Chroma-Sampling in JPEG Compression , Available at:http://users.wfu.edu/matthews/misc/jpg_vs_gif/JpgCompTest/JpgChromaSub.html(Accessed: 24 November 2015).
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