Digital Media Fundamentals: Audio, Video, and Compression Standards
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This section addresses key concepts regarding digital media processing, file formats, and data requirements.
Stereo vs. Mono Audio Data Requirements
Question: What is the difference between stereo and mono audio?
Answer: Stereo audio usually requires twice as much data as mono audio.
Quickest Audio Format for Web Download
Question: Which audio format would be quickest to download from a website?
Answer: AAC (Advanced Audio Coding).
Audio File Format Compatibility
Statement: All audio file formats will work on all media players.
Answer: FALSE. Compatibility depends on the specific media player and the codecs supported.
Defining Bit Depth
Question: What is bit depth?
Answer: Bit depth is the number of bits it is possible to have in each sample or frame of a media file.
Digital Film Creation
A digital film is created from a series of static images played at a high speed. TRUE.
Frame Rate and Sample Rate Analogy
Films have a frame rate per second (fps). This is similar to sample rate. HD film is normally 50 or 60 fps. This can also be measured in frequency (Hz). TV and computer screens have a specification in Hz to indicate the frame rate they support. TRUE.
Digital Film Bit Rate Calculation
Digital films also have a bit rate that accounts for the total audio and image data processed every second. TRUE.
Bit Depth and Audio Quality
Bit Depth is the number of bits available for each sample. The higher the bit depth, the higher the quality of the audio. Bit depth is usually 16 bits on a CD and 24 bits on a DVD.
Compression Artifacts
Data lost during the compression process can cause poor picture quality or even random colored blocks that appear and disappear on the screen. These blocks are called artifacts. TRUE.
Lossy Compression and Bit Depth Reduction
With lossy compression, the original bit depth is reduced to remove data and reduce the file size. The bit depth becomes variable.
Digital Sound Sampling and Storage
Digital sound is broken down into thousands of samples per second. Each sound sample is stored as binary data. TRUE.
Typical Streamed Audio Bit Rates
Streamed music and downloadable files, such as MP3s, are usually between 128 kbps and 320 kbps — much lower than the 1,411 kbps of an uncompressed file. TRUE.
Technology Requiring Least Data
Question: Which of these technologies requires the least data?
Answer: VoIP telephone calls.
Lossless Compression Definition
Lossless compression means that as the file size is compressed, the audio quality remains the same — it does not get worse. Also, the file can be restored back to its original state. TRUE.
Impact of Compression on Audio Quality
Question: Which one of these will not improve the quality of digital audio?
Answer: Compressing the file (especially using lossy methods).
Popular Lossy Video File Formats
Examples of popular lossy video file formats include MP4 and MOV. TRUE.
MP3 and AAC Comparison
MP3 and AAC are both patented codecs and are lossy compressed audio file formats widely supported on different platforms.
The Function of Codecs and Algorithms
Codecs are programs that encode data as usable files, whether images, audio, or video. Compression codecs are designed to remove data without losing quality (where possible). Algorithms work out what data can be removed and reduce file size. TRUE.
Sample Rate Representation
This concept relates to Sample Rate (often represented graphically).
Audio File Bit Rate
Question: What is the bit rate of an audio file?
Answer: The bit rate is the amount of data the file uses each second.
Streaming HD Video Requirements
Videos are also compressed when they are streamed over a network. Streaming HD video requires a high-speed internet connection. Without it, the user would experience buffering and regular drops in quality. HD video is usually around 3 mbps. SD is around 1,500 kbps. TRUE.
High-Speed Connection for HD Streaming
Streaming HD video requires a high-speed internet connection. Without it, the user would experience buffering and quality degradation.