A codec is a device or piece of software capable of encoding or decoding a digital stream or a signal for transmission over a data network. A codec can be for audio or video. The only basic difference between these two is that one is an algorithm designed to compress and decompress audio files and the other is for video files. These two codecs can be divided into two further categories: lossless and lossy compression.
Lossless compression is a data compression algorithm that allows for the compression and decompression of files without any loss of quality.
Lossy compression is a data algorithm that disgards some data in the file to make it easier to transmit. This is usually utilized when network connection is not great. It is most identifiable with video files when they come out pixelated.
With audio and visual files, there is a complex interaction between video quality, bit rate, coding and decoding algorithms, reactivity to loss of data and latency.
The following is a list of Codecs that are in common use today:
- GSM – 13 Kbps (full rate), 20ms frame size.
- iLBC – 15Kbps,20ms frame size: 13.3 Kbps, 30ms frame size.
- ITU G.711 – 64 Kbps, sample-based. Also known as A-law/μ-law.
- ITU G719 – 32/48/64/128 Kbps, 28 ms Frame Size.
- ITU G.722 – 48/56/64 Kbps.
- ITU G.723.1 – 5.3/6.3 Kbps, 30ms frame size.
- ITU G.726 – 16/24/32/40 Kbps.
- ITU G.728 – 16 Kbps.
- ITU G.729 – 8 Kbps, 10ms frame size.
- Speex – 2.15 to 44.2 Kbps.
- LPC10 – 2.5 Kbps.
- DoD CELP – 4.8 Kbps.
- VP8 is codec used for the encoding and decoding of high definition video as either a file or a bit-stream for viewing. The VP8 codec is – in contrast to the H.264 codec – free for use.
- H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding) is currently one of the most commonly used formats for the recording, compression, playback of high definition video. In contrast to VP8, H.264 is not free.