Encoding audio and video

Encoding audio and video

1. Digital audio and video has a sample rate, bit depth and bit rate. They are usually compressed to reduce file size and stream more efficiently over networks.

   • Compression can be lossy or lossless

2. Digital Audio

   • Sounds created on a computer exist as digital information encoded as audio files
   • Digital sound is broken down into thousands of samples per second. Each sound sample is stored as binary data
   • Digital audio quality
     • sample rate - the number of audio samples captured every second
     • bit depth - the number of bits available for each clip
     • bit rate - the number of bits used per second of audio

3. Sample rate

   • the sample rate is how many samples or measurements of the sound are taken each second
   • the more samples that are taken, the more detail about where the waves rise and fall is recorded and the higher the quality of the audio
   • Amplitude - each sample represents the amplitude of the digital signal at a specific point in time. The amplitude is stored as either an integer or a floating point number and encoded as a binary number

4. A common audio sample rate for music is 44,00 samples per second. The unit is hertz so 44,100 samples per second is 44,100 hertz OR 44.1 kilohertz

5. Bit Depth

   • 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
   • A bit depth of 16 has a resolution of 65,536 possible values (ranging from 0 to 65,535)