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Streaming HD Video

As ISP’s provide faster bandwidth speeds, webcams get higher resolution and computers get faster and more core’s – it begs the question – can you now stream in full HD resolution to offer the best video possible as well do it on a free service? I recently watched what was claimed to be full blown HD Stream but after making this full screen and seeing ‘jaggies’ on the diagonal lines (such as the nose for example) – I questioned if this was really HD and what was at fault.

Bandwidth requirements

  • 720p60: 1280×720 gives 0,92 megapixels per frame. If we take a 24-bit color value per pixel (RGB), this means 2,76 MB data per frame, which multiplied with the 60fps gives 1,3 Gbps or 165 MB/s.
  • 1080i60: 1920×1080 means a 2 megapixel frame which translates into 6,2MB per frame. The interlacing cuts the bitrate in half: 6,2MB x 60 / 2 = 1,49 Gbps or 186 MB/s.
  • 1080p60 is obviously double the throughput of 1080i: 2,98 Gbps or 373 MB/s

Hardware

I am using the Logitech 9000 Pro and going from the spec’s page:

  • High-definition video (up to 1600 X 1200*) – * Enhanced from native 2-MP sensor.
  • 720p widescreen mode with recommended system

Now when I tested this HD mode – I need to add that it was dark and only had one light on – that means the camera had to work harder and probably make the image worse that it could have been.

The testing enviroment

Using the Core i7 machine armed with Flash media encoder 3.1 – I set the input and output to 1280×720 at 25fps, the bandwidth to 950 for video and the total bandwidth needed was 1014kbps. In theory I have 1500kbps – so I should have some headroom.  I also recreated the same settings on Wirecast and go to work recording some content and taking some pictures.

The first thing I noticed on Wirecast broadcasting was it was not as crisp even on preview and if you click the picture above to get the full resolution you can see that there is jaggy lines on the cup, the laptop and the words are not that clear.

Now let is turn to Flash Media Encoder 3.1 – straight away you should notice the much sharper picture, the lack of jaggies on the laptop, how easy it is to read the text. The lines you can see running through the picture is the camera trying hard to compensate for low light.

Thoughts

Wirecast will probably get better in Version 4 – as of now it downgrades the quality of either a webcam or a screen capture (a game for example). FME on it’s own of course cannot do camera swtiching live or capture the desktop but armed with the right programs, you could go so way to get them features.

The bottom line is just because you *think* you are broadcasting in HD does not mean the end result is true HD Quality. The stream above for example is still worse in Quality than a proper 720P Movie – streaming has a long way to go yet.

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