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Bandwidth

Bandwidth is often used for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps).

In general, a link with a high bandwidth is one that may be able to carry enough information to sustain the succession of images in a video presentation.

Video Buffering

It is caused when the client runs out of data in memory (the buffer) and must wait for more to arrive. The client will always run out of data if the bit rate of the incoming stream exceeds the current available bandwidth.

A buffer is temporary holding pen in the computers memory for data for inputs (e.g., to software) or outputs (e.g., to a printer) until the process can deal with it.

Buffers are needed when data comes in faster than it can be processed, or when the rates vary, like in a printer spooler.

In regards to video streaming, buffering occurs when a streaming media player saves portions of a streaming media file to local storage for playback.

Streaming media players usually buffer a small percentage of a media presentation before play begins. Buffering can also occur during the streaming media presentation, when the presentation's required bandwidth is greater than the available bandwidth needed to view the file in real-time.

How to calculate?

Streaming media storage size is calculated from the streaming bandwidth and length of the media using the following formula (for a single user and file):

length of video (in seconds) x video bit rate (in bit/s) / (8 x 1024 x 1024) = storage size (in megabytes)

If the file (300 kbit/s) is stored on a server for on-demand streaming and this stream is viewed by 1,000 people at the same time using a Unicast protocol, the requirement is:

video bit rate (in kbit/s) x estimate no. of people = no. of bandwidth (in kbit/s)

Example:
300 kbit/s x 1,000 = 300,000 kbit/s = 300 Mbit/s of bandwidth

Click here to use the CALCULATOR

Estimate live streaming total traffic: video bit rate (in bps) × length of video (in seconds) × estimate no. of viewer / (8*1024*1024) = Number of MB transferred

Click here to use the CALCULATOR


Video Quality

Video quality is a characteristic of a video passed through a video transmission/processing system, a formal or informal measure of perceived video degradation (typically, compared to the original video). Video processing systems may introduce some amounts of distortion or artifacts in the video signal, so video quality evaluation is an important problem.

Bit rate is a measure of the rate of information content in a video stream. It is quantified using the bit per second (bit/s or bps) unit or Megabits per second (Mbit/s). A higher bit rate allows better video quality. For example VideoCD, with a bit rate of about 1 Mbit/s, is lower quality than DVD, with a bit rate of about 5 Mbit/s. HD (High Definition Digital Video and TV) has a still higher quality, with a bit rate of about 20 Mbit/s.


What should be matched?

Video bit rate should match with correct video size, in terms of video bit rate, it includes both Video and Audio bit rate.
i.e. Video bit rate + Audio bit rate = Total bit rate

Format Resolution Video and Audio bit rate (kbit/s) Total bit rate
1080p 1920 x 800 3502 128 ~3.6 Mbit/s
480p 854 x 356 806 103 ~1 Mbit/s
240p 400 x 166 255 59 ~300 Kbit/s

Click here to watch VIDEO DEMONSTRATION

What’s the difference between 240p and 720p?

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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