Friday, July 10, 2009

Video Bandwidth

8-bit YCbCr422 data, 30 frames/second, CIF 352 x 240 CMOS sensor. So it is 2 bytes per pixel (4 pixels have 4+2+2 = 8 bytes, one pixel has 2 bytes), the bandwidth is (raw data into processor):
352x240 pixels x 2 bytes x 30 frames = 5.07M bytes / second
For 420 data, it is 1.5 byte/pixel (12 bits)

1 comment:

  1. Web casting, or broadcasting over the internet, is a media file (audio-video mostly) distributed over the internet using streaming media technology. Streaming implies media played as a continuous stream and received real time by the browser (end user). Streaming technology enables a single content source to be distributed to many simultaneous viewers. Streaming video bandwidth is typically calculated in gigabytes of data transferred. It is important to estimate how many viewers you can reach, for example in a live webcast, given your bandwidth constraints or conversely, if you are expecting a certain audience size, what bandwidth resources you need to deploy.

    To estimate how many viewers you can reach during a webcast, consider some parlance:
    One viewer: 1 click of a video player button at one location logged on
    One viewer hour: 1 viewer connected for 1 hour
    100 viewer hours: 100 viewers connected for 1 hour…

    Typically webcasts will be offered at different bit rates or quality levels corresponding to different user’s internet connection speeds. Bit rate implies the rate at which bits (basic data units) are transferred. It denotes how much data is transmitted in a given amount of time. (bps / Kbps / Mbps…). Quality improves as more bits are used for each second of the playback. Video of 3000 Kbps will look better than one of say 1000Kbps. This is just like quality of a image is represented in resolution, for video (or audio) it is measured by the bit rate.

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