12. Media Editing
All Past Paper Questions: https://docs.google.com/document/d/1HBnOzgTHTnIAohIFxem7lsppqOqvDVgEyuEiDvb500I/edit?usp=sharing
Other
Codecs
-
how video codecs are used?
- short form of coder-decoder
- used to encode/decode digital data stream
- used to compress data to reduce transmission bandwidth
- the decoder reverses the encoding for playback
- there are many different types of codecs
- without codecs, downloads will take very long
- its common to need 10-12 codes to play users's media
-
features
- to reduce the file size of audio and video files
- type of encoding
- encoded media is similar is quiality, but smaller in size
- can also be lossy
- (just the lossy & lossless compression parts)
- lacks information present in original video
- decompressed video has lower quiality now
- not enough information to accurately re-construct the original media
- each media file has a codec program
- codec
- used to encode
- into appropriate format
- changes original data into a form
- that can be used by external processes
- decodes for playback
- used to encode
- (en)/(de)coding usually refers to process of ADC and DAC
- can apply to images/audio/video/signals-from-sensors/control-systems
Audio Editing (Software)
Audio Files
-
samples
- digital audio is a series of discrete bursts
- frequency of samples stored is high
- so it sounds continous
-
sampling rate
- number of samples in a given period of time
- high sampling rate = high quality = high storage usage
- low sampling rate = low quality = low storage usage -> leads to distortion
- since less gaps between each sample
- sounds more continous
- theres also a minimum rate at which samples need to be taken
- to reproduce original sound
- question
- what is sampling resolution and how it affects the audio quality
- number of bits per sound sample
- maximum accuracy of each measurement taken of a wave form when creating an audio file
- high = more accuracy = more file size
- when converting from analogue to digital
- digital audio is usually uses 8-bit / 16-bit resolutions
- 8-bit resolution was used in earliest sound cards
- and old recordings
- each sample can take one of 256 different values
- not enough
- 16-bit
- standard for CD drives and new sound cards
- each sample can take one of 65536 different values
- good quality
- these values are all per channel
- in stereo, two channels are used (Left & Right)
- doubles the sampling and memmory requirement
- what is sampling resolution and how it affects the audio quality
- number of samples in a given period of time
-
sampling resolution
- no. of bits used to carry data in each sample of sound
- high sampling resolution = high quality = high storage usage
- low sampling resolution = low quality = low storage usage
- since less number of bits used to store each sample
- usually, its 8-bits or 16-bits / 64-bits or 128-bits
- explanation:
- for example, if sample resolution is 8-bits,
- each sample can have 256 values
- no. of bits used to carry data in each sample of sound
-
stero sound
- usually, sound has only one channel (mono)
- for stereo, you need to have two tracks
- Left and Right
Features
-
trimming
- cuts part of sound
- reducing the length of track
- enables unwanted sounds to be removed
-
adjusting sampling rate
- increase
- to improve sound quality
- decrease
- to save disk space
- increase
-
adjusting sampling resolution
- increase
- to improve sound quality
- decrease
- to save disk space
- increase
-
fading
- fading in
- occurs at beginning of sound clip
- sound gradually gets louder
- volume stops increasing when required sound level is reached
- uses
- can use when there is a clear section
- of silence before track starts
- to soften introduction of sound at start
- can use when there is a clear section
- fading out
- occurs at end of sound clip
- sound gradually gets softer
- sound disappears all together
- uses
- can use when audio has no obvious ending
- fading in
Video Editing (Software)
Features
-
trimming
- old answer
- position the cursor on the timeline (start/end of the clip)
- when the trip handles appear
- drag it to perform the trim
- achieved by removing unwanted footage
- new answer
- how to trim
- position the cursor on the timeline
- trim handle will appear
- trag it to tim
- and action the trim
- to remove unwanted parts of the video
- cut a long film into small part
- cut the beginning
- eg: camera was recording before it started
- to pull out a key part of a video
- to make videos more interesting by removing boring introduction
- ?? to bring audio and video to sync, so its more natural ??
- how to trim
- old answer
-
adding sound
- old answer
- open audio and video files that he wants to add/merge
- drag and drop the sound files to the timeline
- videos are placed in the video track
- audios are placed in the audio track
- new answer
- can invoke emotional response
- increases engagement / enjoyment
- can grab audience attention by making it more interesting
- narrator can provide further content
- can clarify video
- add sound effects
- heighten the impact of explosions
- to add a clear soundtrack without background noise
- old answer
-
adding captions
- old answer
- choose the style
- right click and select where to place it
- can add "title" to the video track
- double click in the "title" frame
- in the preview window
- and type/paste/edit the text
- new answer
- how to add caption?
- click on frame (at required position)
- select "Text Box" / "Caption"
- type the text
- to provide additional information for viewers (for a better understanding)
- accessiblity for deaf people
- what has been said is shown on the screen
- can be read
- so, nothing is missed
- if language used is foreign
- to watch without audio,
- eg: in pubic
- in quite area
- might speak a different language
- how to add caption?
- old answer