Let’s compare HD-SDI with MPEG and with HDMI.
HD-SDI vs MPEG
MPEG: Compressed AV encoding & storage
MPEG (which stands for the Moving Picture Experts Group) was established in 1988 to set standards for audio and video compression, transmission and storage.
This first MPEG compression standard was designed in 1993 to allow moving pictures and sound to be encoded for digital storage media at up to about 1.5 Mbps, the bitrate of a compact disc (CD) and video CD. MPEG-1 down samples images and uses picture rates of just 24-30 Hz. This standard also includes MPEG-1 Audio Layer III (MP3), the popular audio compression format.
Broader in scope, MPEG-2 (1995) allows transmission of moving video and audio data for broadcast-quality TV, supporting interlacing and high definition. This compression scheme is used for over-the-air digital TV signals, digital satellite TV services, digital cable TV signals and DVD video.
This was intended for HDTV compression but was merged with MPEG-2 and no longer exists. Don’t confuse MPEG-3 with MP3, which is the audio layer 3 of MPEG-1.
MPEG-4 was created for coding of audio-visual objects (in 1998). More efficient video coding results in higher compression rates than MPEG-2 and it moves closer to computer graphics applications.
• H.264/MPEG-4 AVC
The newer MPEG-4 AVC standard (Advanced Video Coding, also known as MPEG-4 Part 10 or H.264) was created in 2003 and is a commonly used format for the recording, compression and distribution of high definition video (e.g. HD DVD and Blu-ray discs). It is also widely used by streaming internet services such as YouTube and iTunes as well as web software such as the Adobe Flash Player.
Main differences with HD-SDI:
Although MPEG-4 Part 10 is suitable for high-definition video, this standard still uses much lower bitrates and compresses the signal down, which results in a general loss of quality. HD-SDI transmits original, uncompressed AV signals.
Because MPEG was designed for moving images (motion pictures), compression artefacts (distortion of the image) are obvious when the image is frozen, so MPEG is not suitable for situations where high-quality high-definition still pictures are required.
HD-SDI vs HDMI
HDMI: Uncompressed AV transmission cables
HDMI stands for High-Definition Multimedia Interface and is a compact audio/video standard for transmitting uncompressed digital data. It is in use since 2003.
HDMI connects digital AV sources (e.g. set-top boxes, DVD players, PCs, video game consoles, AVCHD camcorders) to compatible digital TVs, audio devices and video projectors.
It supports uncompressed TV or PC video formats, including high-definition video and up to 8 channels of compressed or uncompressed digital audio as well as an Ethernet data connection and Consumer Electronics Control (CEC) connection, on a single cable.
A standard HDMI cable supports video formats up to 1080i and 720p while a high-speed HDMI cable supports 1080p.
Main differences with HD-SDI:
HDMI cables are mostly used for consumer applications such as home entertainment and are generally only up to a few metres in length, while HD-SDI is predominantly used in professional AV and broadcast environments.
HDMI is mostly intended for connecting a media playing source to a monitor and not that suitable for transmitting signals from a recording device. HD-SDI is the best choice to use with recording cameras because it is a more durable and reliable connection, partly thanks to a locking BNC connector, which HDMI doesn’t have.
Furthermore, HDMI doesn’t transport time code while HD-SDI does.
Article Contribution: Written in behalf of Aucom.com.au – Australia’s largest security camera and CCTV Camera integrator and other surveillance solutions specific for your security requirements.