High-definition video provides a clearer and more defined picture than the consumer digital video often found on standard DVDs. When streaming HD video, you need to stream it at a rate that's high enough to provide the full content contained in the HD video to view the stream in full high definition. Home networks are better suited for this type of streaming than the Internet because they can often support the large bandwidth and connection speeds required to stream large amounts of content.
Each frame in a video has a certain number of pixels, each represented by a computer bit. An HD video is high definition because it contains more pixels per frame than a lower-quality video, and the additional pixels provide more definition to the picture. Bit rate is a measure of the amount of data streamed over a given period, measured in bits per second. A higher bit rate generally implies a higher-quality video, since more bits are included for each frame, which increases the definition of the picture. However, higher bit rates also require increased bandwidth and faster connections to transmit more data in a given period.
Bit rate is one of three factors that influence the quality of a video. The codec used to encode the video is also important. By compressing the video, the codec removes data, some of which can be restored when the video stream is decompressed. The resolution of a video is the third factor that influences quality because it determines how much detail is available for viewing. Increasing the resolution of a video won't improve the video quality if the bit rate is not high enough to stream the high-definition content to the display.
HD Streaming Bit Rate
On average, the ideal bit rate for streaming HD video on a home or any other network is 28 megabits per second for an HD video encoded with the H.264 codec with a resolution of 1080p, or 1920 by 1080 pixels. This bit rate provides enough bits for a high-definition video to display at a high-definition resolution. The video can be decompressed so that any quality lost through compression is unnoticeable.
Streaming at Lower Bit Rates
It's possible to stream an HD video at a bit rate lower than 28 Mbps. When you do that, you eliminate some of the picture definition that makes the video HD. The result is that, even though you stream an HD video, the viewer doesn't receive an HD video. Some online media providers advertise online streaming of HD videos over the Internet. While it's true that they may be streaming HD videos, unless the bit rate is 28 Mbps or higher, you won't receive an HD video, and you won't view the video in full high definition.
- Photo Credit Thomas Northcut/Photodisc/Getty Images