Video compression reduces the quantity of data used to represent video content, making video files smaller with little perceptible loss in quality. Compressed files are easier to transmit over a network and easier to store.

The Video Codec

A video codec is a software module that enables video compression or decompression of digital video. Codecs encode a stream or signal for transmission, storage, or encryption and decode it for viewing or editing.

Lossless vs. Lossy Video Compression

Video can be compressed using either lossless or lossy methods. With lossless compression, each pixel is unchanged, resulting in an identical, bit-for-bit image after decompression. With lossy compression, the resulting video sequence is different from the original, but good enough for use. In most cases, lossy methods produce much smaller compressed files than lossless methods, while still meeting the requirements of the application.

Codec Standards

All of the following codecs are lossy, so the reconstructed image following compression is not exactly like the original.

• SM4 is a proprietary, MPEG-4 based Verint codec designed to encode quickly and provide good perceptual quality. It is the default setting for most Verint IP cameras and encoders.
• MPEG-2 produces high-quality video at the expense of a lower compression ratio and at a higher bitrate, with the frame rate locked at 25 fps (PAL) and 30 fps (NTSC).
• MPEG-4 is the most widely used codec for video security and offers better quality than MPEG-2, with supported resolutions from CIF/3.75 fps at 128 kbps to D1/30 fps at 6 Mbits/s.
• H.264, also known as MPEG-4 AVC or MPEG-4 part 10, is an emerging standard that offers new tools to improve video compression when compared to MPEG-4 and MPEG-2. Current implementations of H.264 offer only limited functionality and require CPU-intensive processing. This translates into sub-par performance of the codec versus more mature codec implementation and higher solution costs.
• WMV9 (VC-1) is Microsoft’s Windows Media Video version 9 codec, a proprietary codec for low bitrate, streaming applications.
• MJPEG (Motion JPEG) is an informal name for multimedia formats in which each frame of a video sequence is separately compressed as a JPEG image. M-JPEG is often used by IP-based video cameras via http streams.

Choosing the Right Codec

Codec performance is generally a tradeoff between bitrate and image quality. Before choosing a codec, define your requirements keeping the following in mind:

• The maximum and minimum required sustained frame rate
• Whether recording/monitoring is required at all times or only when motion or an event occurs
• The resolution/frame rate required when recording motion, an event, or an alarm
• The length of time a video sequence must be stored
• The level of latency that is acceptable
• System robustness and security issues
• How much network bandwidth is required

Always compare either (1) compressed image quality at equivalent bitrates or (2) various bitrates at an equivalent level of image quality. It is advisable to test codec performance using video sequences that reflect the kind of motion and environmental conditions that will be present in the field because the type of data that is recorded has an impact on codec performance. High-motion or low-light conditions can affect image quality at different frame rates and resolutions. When comparing bitrates, it is preferable to verify a codec’s performance by recording video for a sustained period of time at different settings. Always configure product settings to your needs.

Codecs for Nextiva Intelligent Edge Devices

Nextiva edge devices help optimize digital video with state-of-the-art video compression and dual streaming capabilities. Verint developed the SM4 proprietary codec as the default setting for most Nextiva IP cameras and encoders. It is MPEG-4 and H.263-based and designed to encode quickly with good image quality, while reducing the required bitrate by about 5% - 20% compared to MPEG-4 Simple Profile. Nextiva also features a well-optimized MPEG-4 Simple Profile solution that is based on the industry-standard codec for easy interoperability with other systems and devices and greater system flexibility.