MJPEG vs. MPEG4

4XEM's IP Network Cameras and IP Network Video Servers feature either MJPEG or MPEG4 video compression methods*. Both technologies have their own strengths and weaknesses, which should be considered when choosing the ideal camera for your application.

MJPEG (Motion JPEG)

MJPEG is a video compression method utilized in 4XEM's W-2100, W60, W80*, WL80* and WPTZ* IP Network Cameras and the IPVS1 and IPVS4 IP Network Video Servers. A network camera/video server using MJPEG video compression captures individual images at rates of up to a maximum of 30 individual frames per second. The captured images are presented in succession, thus producing a stream of video. This is referred to as Motion JPEG with each image frame being an entire JPEG compressed image.

The result of compressing all information on each frame is high picture quality** but it requires more information to be transmitted and stored. Thus, when compared with MPEG4, bandwidth usage is greatly increased with MJPEG, as is the disk space required for storage. Audio support is possible with MJPEG cameras but audio/video synchronization is poor, and it involves a substantial increase in both required hard drive space and bandwidth usage. As such, 4XEM's IP Network Cameras and Video Servers featuring MJPEG as the video compression method do not feature support for audio.

Fig. 1a, 1b and 1c - Three individually transmitted MJPEG image frames

With MJPEG Video Compression each image is transmitted in full regardless of whether the picture has changed or not. In the above example, with each camera box that is added, more image data is transmitted thus increasing bandwidth usage. As you can see from figure 1a through 1c, the 4XEM logo and the bottom row of W50 boxes have not changed and were transmitted with each frame of data.

MPEG4

Currently, most of the 4XEM IP Network Cameras and IP Network Video Servers use MPEG4 as the video compression method. With MPEG4, only changes to each image on successive frames are actually transmitted, not the complete image. The result of sending only image changes is both reduced bandwidth usage and storage space required, however MPEG4 has a lower image quality when directly compared to MJPEG. IP Network Cameras and Video Servers featuring MPEG4 can capture audio as well as images, with the audio and video being fully synchronized***.

Fig. 2a, 2b and 2c - Three individually transmitted MPEG4 image frames

With MPEG4 Video Compression only the changes to each frame of data are actually transmitted. As can be seen in Fig. 2b, the 4XEM logo and the bottom row of boxes disappear. There was no change to the logo or the bottom row of boxes. As a result, that part of the image frame does not need to be retransmitted. Fig. 2c shows the continuation of transmission. Only the changes are transmitted. In this case the last W50 camera box that was added to the stack of boxes.

*Certain 4XEM IP Network Cameras support both MJPEG and MPEG4 Video Compression. These cameras feature Dual Codec support for both MPEG4 and MJPEG video compression selectable through the camera's configuration pages. Also, with the ability to configure these cameras to use MPEG4 as the compression method, audio is a supported feature as a result.

**Quality is subject to the configuration settings chosen through the camera's/video server's configuration pages.

***Audio and Video synchronization is subject to Bandwidth availability. In low bandwidth environments, audio support may not be feasible.