DAJOERI Forum :: Website and technical hints
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 Subject :Streaming Speed and Video Playback.. 25-02-2011 22:55:49 
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Location: Clearwater
 

Our website comprises more and more videos. To smoothly play them back it is helpful to know some video basics.

Streaming speed is given in Mbps. Mega-Bit per second.

A bit is a yes/no information. For a lamp to turn on or off with a switch one uses 1 bit. Don't confuse b=bit with B= bytes. Bit is the smallest unit of data storage. 8 bits equal a byte -> 8b = 1B

Storage of data is expressed in bytes B. E.g. 1KB. 1MB, 1GB, 1TB. For transporting data over the Internet one typically uses 'bit per second' bps, for example: 10kbps, 5Mbps (b is lower case!).

Since a video consists of 15-30 frames per second, a lot of continuous information has to be received. Depending on the size of the image window, 0.5 to 8 Mbps may be used to produce a good quality picture. (1Mbps = 1,000,000 bits per second). For the size of the image window one uses a number and the letter P.

The number represents the amount of pixels of the vertical side of the image window. A pixel is the smallest unit of an image. You could also use the word picture-dot. The P means progressive. Each picture frame is completely built. Then the next ... etc. In contrast, there are i=interlaced.

TV images (NTSC) have have 60 half-fields (interlaced) instead of 30 frames (progressive). This goes back to the television date of origin. Then, the 50 half-fields caused less screen flickering than 25 full images.

Computer screens - as opposed to TV screens - are working by using the progressive method (P).

Name | image size | Total pixels per frame | -> Streaming minimum / optimum

240P      426x 240 = 0102 Total Millions of Pixels -> 0.3Mbps / 0.5Mbps
360P      640x 360 = 0230 Total Millions of Pixels -> 0.6Mbps / 1.2Mbps
480P      854x 480 = 0410 Total Millions  of Pixels -> 1.0Mbps / 1.8Mbps
720P    1280x 720 = 0922 Total Millions of Pixels -> 2.5Mbps / 5.0Mbps
1080P  1920x1080 = 2073 Total Millions of Pixels -> 4.0Mbps / 8.0Mbps

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 Subject :Example of image size.. 26-02-2011 10:28:35 
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Location: Clearwater
 
video1

Here is an example of a 360P image size. To stream 360P with somewhat useful quality, it takes about 0.6 Mbps. This corresponds to a weak ADSL connection.

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 Subject :How fast is your connection?.. 26-02-2011 22:56:04 
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Joined: 21-11-2009 07:52:58
Posts: 115
Location: Clearwater
 

Perform a test at Speedtest.net

This is the download-result of my Internet connection:

video2

43Mbps download is very fast. We have a fiber optics connection to our house (FIOS 43Mbps DOWN and 39 Mbps UP).

The potential streaming speed of your connection depends on two factors:

-your connection
-your plan with the service provider (Swisscom, Cablecom, etc.) fiber: 15-100 Mbps Cable: 5-25 Mbps DSL: 0.7-20 Mbps DialUp: 0.06 Mbps

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 Subject :Actual steaming speed.. 26-02-2011 23:03:15 
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Joined: 21-11-2009 07:52:58
Posts: 115
Location: Clearwater
 

Your actual streaming speed in turn depends on several factors:

1. The measured streeming speed
2. The output speed of the server
3. The transport speed of the signal

1) Can be measured by speed tests. (see above).

2) Depends on the load of server. At peak times the flow rate is limited. The server of our Web site is located in Houston Texas and is operated by SITEGROUND. Our server is efficient around the clock and provides up to 32Mbps download SPEED.

YouTube has many servers around the world. Here it is difficult to provide better and worse times for the streaming speed. There's nothing more than try.

3) The route of the video stream may take different routes. Often the data packets are sent on different routes and at the final location reunited. Here are some bottlenecks when a data path is blocked or overloaded. Therefore the speed may be very good one day and the next day bad.

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 Subject :Realtime streaming on our website.. 26-02-2011 23:20:49 
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Joined: 21-11-2009 07:52:58
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Location: Clearwater
 

The videos on our site to stream in real time, i.e. after a few seconds buffer time, the video starts to run. be sure to use the latest Flash player.

The videos on our site are all encoded in FLASH (H.264), 720P. (1280x720 pixels). They stream with an average of 2.6 Mbps (megabits per second).

video3

The DOWNLOAD strip moves the right. The faster the better. Ideally, the DOWNLOAD shopuld be faster than the movement of the playhead, which indicates the progress of the video playback. If the PLAYHEAD catches up the DOWNLOAD-Strip, there will be congestion, hence a faltering of the playback. In this case, the flow rate is insufficient. In this case, there is a simple remedy. Click the PAUSE button click, wait and see. Once the DOWNLOAD Strip has moved enough to the right, start video again (with the same button). (Warning: The download Strip and the PAUSE button is only visible when you move the cursor into the image window.)

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 Subject :Realtime streaming on YouTube.. 26-02-2011 23:47:36 
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Joined: 21-11-2009 07:52:58
Posts: 115
Location: Clearwater
 

YouTube is also working with FLASH. You can also select the video format, usually 240P, 360P, 480P, 720P and 1080P. The larger the video format, the more demands on your current speed. If you experience congestion, there are 2 solutions:

1) Choose a smaller image size and take into account a lesser video quality.

2) Click the PAUSE button and wait until the download strip has moved enough to the right.

video4

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 Subject :Full Screen.. 26-02-2011 23:50:34 
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Joined: 21-11-2009 07:52:58
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Location: Clearwater
 

Full-screen can be set with the appropriate button. However, there are some limitations:

1) Old video cards are not suitable for full-screen mode.

2) Use Flash Player 10 or higher. Lower FLASH versions do not support the Full-Screen mode.

3) If your image sequences do not run smoothly, it is becasue your processor is too weak and/ or your video card doesn't have sufficient capacity. Since all our videos are processed by using the H.264 codec, you need sufficient processor power, adequate RAM (2GB or more) and a powerful video card.

Remedy for poor performance: Use another, newer computer or switch to YouTube and select 240P or 360P. Full-screen mode of course makes mainly sense when you watch videos in 720p or 1080p. Then you have an image with optimum resolution. 240P, 360P and 480P also allow to be viewed in full screen mode, but in lower resolution quality (washed out and blurry picture).

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 Subject :Re:Streaming Speed and Video Playback.. 27-02-2011 10:02:48 
Webmaster
Joined: 21-11-2009 07:52:58
Posts: 115
Location: Clearwater
 

Instead of watching the video in real time, you can also download it to your hard disk. All videos are available in 1080p with the encoding-> wmv (Windows Media 9). The videos can be downloaded from our Download section (-> Resources). Be aware that you are looking between 150 to 750 MB per video. Your download time might be from several minutes to a few hours, depending on your Internet connection. Our server is very strong and if transport bandwidth is sufficient, it can stream up to 3.8MB/sec. That means that a 750MB movie could be downloaded in about 3.5 minutes.

Once the download is complete, you can replay the video by using Windows Media Player. The required processing power is lesser critical than the use of FLASH/H.264. A Pentium IV should be still fine to play the video.

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 Subject :Re:Streaming Speed and Video Playback.. 27-02-2011 10:14:54 
Webmaster
Joined: 21-11-2009 07:52:58
Posts: 115
Location: Clearwater
 

The above information helps you to understand in dealing with Internet videos. We have tried to explain the most important aspects. If you have any questions or problems, you can easily leave a message. You need a user account and must log in first.

Have fun watching the DAJOERI videos.

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