Within the H.264 standard, there are many methods of compressing, transmitting, and validating the data, so H.264 video compression is not always recognizable by every H.264 engine. You may or may not be able to play a given H.264 video file with a given H.264 video player. Therefore, an H.264 video stream from one supplier’s camera might not be compatible with another supplier’s recorder, although sometimes only minor tweaking or a slight modification can fix the compatibility issue.
Match compression to the application. H.264 is designed for and used in applications that require streaming HD video quality at resolutions up to 1080p. H.264 takes up less bandwidth and storage, especially at the real-time frame rates (30fps) most customers want. However, because of how the compression format does its job, not every “frame” is a complete picture. Instead, full frames (I-frames) alternate with frames that contain partial information (P-frames and B-frames), thus taking advantage of the redundancy between neighboring frames to achieve higher compression rates.
However, in MJPEG recordings, each frame is a complete picture, which can be useful in situations where the camera is farther away and/or more detail is needed. But at 30 fps, MJPEG creates too much data to be practical in many applications. For higher megapixel camera recording (greater than 3 megapixels), MJPEG is used at lower (less than 30 fps) frame rates to compensate for the larger file sizes and resolution. MJPEG is better suited for high-quality, frame-by-frame stepping since each frame is a complete picture.
To freeze an H.264 picture for viewing or forensic use, many security video applications would either have to jump to the next I-frame, which contains a full picture’s worth of information, to build a complete picture from several frames of video, or to convert the on-screen display to a JPEG picture. If encoded in MJPEG, on the other hand, any individual frame can be obtained without data or picture loss due to conversion.
End user drives the bus
End-user demands for real-time recording and HD image quality are driving adoption of H.264 for viewing and recording applications. To address a variety of system requirements, cameras provide multiple streams that can enable simultaneous H.264 viewing at 30fps and MJPEG recording at a lower frame rate for forensic investigations.
Understanding all aspects of implementing H.264 is critical as the industry continues to make the transition. Importantly, nothing on the horizon appears poised to take the place of H.264, so it’s here to stay, and its impact on the industry will continue to be felt. The market’s demand for HD images and real-time frame rates plays to the strengths of H.264 to provide superior resolution with smaller video file sizes that lower a system’s bandwidth and storage requirements.