Video Encoding

Streaming Video - Everything You Need To Know

Encoding means to take a video source such as live TV and process it for storage on digital media like hard drives. Encoding a video has the advantage of making it accessible, searchable, editable, repurposable, and so on. The quality, frame rate, and frame size of your video content is largely determined by the codec (compressor/decompressor). By using codecs for compressing audio and video data into smaller packages that do not consume as much hard disk space or network bandwidth, multimedia applications can provide richer and fuller content.

Variable Bit Rate Encoding

Variable bit rate (VBR) encoding varies a video clip's playback bit rate, giving more bandwidth to scenes that are hard to compress, and less to scenes that are easy. Compatible with SureStream and broadcasting, VBR encoding generally provides superior video quality to constant bit rate (CBR) encoding. VBR makes the most difference in videos that have a mix of high-action and low-action scenes because it can steal bandwidth from low-action areas to give to high-action areas. This is particularly useful for improving video quality at low bit rates.

To illustrate how VBR encoding works, suppose you encode a video for a DSL/cable modem audience at 225 Kbps. With CBR, the video gets 225 Kilobits of encoded data each second. With VBR, though, each second of video may be encoded at a different rate. One second may have 150 Kilobits of data, for example, while another second has 300 Kilobits. The VBR clip will have a streaming bit rate of 225 Kbps, though, just like a CBR clip. So you do not need to worry that a VBR clip will underuse or overload a connection's bandwidth.

Two-Pass Encoding

With two-pass encoding, which is used only when encoding from a digitized source file, encoding application runs through the entire source video once to gather information about how best to encode the streaming clip. It then makes a second pass to encode the streams. Two-pass encoding can substantially increase clip quality, but it requires more encoding time. The first pass takes about as long as it would to encode the source file for one target audience. Although two-pass encoding helps when you use constant bit rate encoding, it provides greater benefit for variable bit rate (VBR) encoding, which is described above.

Encoding Applications:

With streaming video, it is all about the access. The pictures may be fuzzy and the sound occasionally garbled. But when a Web user clicks on that link and gets video on-demand, that is power.

Fortunately, the streaming tools are rapidly growing more and more powerful. The quality today is significantly better than the quality six months ago. And it continues to improve at a phenomenal rate.

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