Video Standards

1. What is MPEG4?

   MPEG-4, introduced in late 1998, is the designation for a group of audio and video coding standards and related technology agreed upon by the ISO/IEC. The primary uses for the MPEG-4 standard are web (streaming media) and CD distribution, and broadcast television. Key points of MPEG-4 are the following:

   • Uses key-frames and object oriented differential compression format
   • At low bandwidth availability, priority is given to frame rate
   • Bandwidth is directly affected by amount of motion in the frame (since frames may differ in size)
   • May raise problems when used as evidence in court, since non-keyframe frames contain only the differential between the previous and subsequent frames.
   • Some proprietary implementations and licensing is required.

   Simply described, MPEG’s basic principle is to compare compressed images to be transmitted over the network, using the first compressed image as a reference frame (called an I frame), sending it and only the parts of following images that differ from the reference image (B and P frames). The network viewing station will then reconstruct all images based on the reference image and the “difference data” contained in the B and P frames.

   A result of applying MPEG video compression is that the amount of data transmitted across the network is less than that of Motion JPEG. This is illustrated below where only information about the differences in the second and third frames is transmitted. MPEG is in fact far more complex than indicated above, and parameters such as prediction of motion in a scene and identifying objects are additional techniques or tools used within MPEG.

2. What are the Key Adavantages of MPEG-4?

   • Reduces the amount of storage needed
   • Increases the amount of time video can be stored
   • Reduces the network bandwidth used by the surveillance system

3. What are typical applciations of MPEG-4?

   An example of a situation where MPEG-4 could be utilized to solve a bandwidth issue is if the video traffic was going be part of an existing 100Mbs network. The network would be saturated sooner if MJPEG cameras were put on it.

   Another example of where MPEG-4 could be the solution is if the storage on the NVR was relatively small and archiving could only be done once a day.

   A third example of utilizing MPEG-4 benefits would be if the length of time desired to store archives was unusually long, or just too long, if MJPEG images were stored

4. What is MJPEG?

   Motion JPEG (M-JPEG) is a video codec where each video field (frame) is separately compressed into a JPEG image. The resulting quality of video compression is independent from the motion in the image (which differs from MPEG video where quality often decreases when footage contains lots of movement). Characteristics of M-JPEG):

   • At low bandwidth availability, priority is given to image resolution (i.e. transmitted images would maintain their quality, however some images would be dropped).
   • Minimum latency in image processing.
   • Images have a consistent file size.
   • Still the most widespread picture compression format used today.

   Similar to a digital still picture camera, a network camera captures individual images and compresses them into a JPEG format. The camera can capture and compress, for example, 30 such individual images per second (30 fps), and then make them available as a continuous flow of images over a network to a viewing station.

   At a frame rate of about 16 fps and above, the viewer will perceive full motion video. As each individual image is a complete JPEG compressed image, they will all have the same guaranteed quality, determined by the compression level as defined for the network camera or network video server.

5. What are the Key Advantages of MJPEG?

   • Ideal for courtroom evidence
   • Frame by frame playback offers more frames to view
   • Technology is simpler; this can lower the price of a camera or video server
   • Less delay issues when used with audio
   • At low bandwidth availability, priority is given to the Image Resolution
   • Easier to work with if using photo editing s/w

6. What are typical applications of MJPEG?

   An example for utilizing MJPEG complete frame by frame playback benefit would be if the video playback was going to be used in court cases; MPEG-4 could be challenged.

   Another example of when to use MJPEG is if staying within a budget for a project means buying cameras without MPEG-4 capability, but having other key features desired.

   A third example is if in a situation where Image Resolution is the priority and the bandwidth is limited, then MJPEG would be the way to go.

7. What is H.264?

   H.264 is a new video compression scheme that is becoming the worldwide digital video standard for consumer electronics and personal computers. In particular, H.264 has already been selected as a key compression scheme (codec) for the next generation of optical disc formats, HD-DVD and Blu-ray disc (sometimes referred to as BD or BD-ROM) H.264 has been adopted by the Motion Picture Experts Group (MPEG) to be a key video compression scheme in the MPEG-4 format for digital media exchange. H.264 is sometimes referred to as MPEG-4 Part 10 (part of the MPEG-4 specification), or as AVC (MPEG-4's Advanced Video Coding). This new compression scheme has been developed in response to technical factors and the needs of an evolving market:

   • MPEG-2 and other older video codecs are relatively inefficient.
   • Much greater computational resources are available today.
   • High Definition video is becoming pervasive, and there is a strong need to store and transmit more efficiently the higher quantity of data of HD (about 6 times more than Standard Definition video).

8. What are the Key Advantages of H.264?

   • H.264's high compression allows for higher framerates at lower bandwitdh vs MJPEG or MPEG-4.
   • High compression creates small file sizes; Less space required on server.
   • Great for low traffic areas as only changes will be sent.
   • Higher image quality vs MPEG-4