VideoSoap

We also spoke about VideoSoap on the fourth page of our All-in-Wonder 9700 Pro preview. Again, to briefly recap, the VideoSoap feature of the All-in-Wonder 9700 Pro gives the card the ability to pass up to four filters on an incoming video stream in order to decrease noise or just make the video look better in general. The filters, blur, despeckle, sharpen, and two combination filters, are passed over the video using the R300's pixel shaders and the amount of filtering done can be adjusted by the user. There are also preset VideoSoap settings for a variety of situations, including sports and news shows.

Again, the purpose of VideoSoap is to make recorded video look better. The filters can only be applied when recording video, not when just watching live television. We think that the reason for this is because VideoSoap does end up using a good amount of CPU power to process and filter each frame and it would not be desirable to have a high CPU utilization while just watching television. To give you an idea of how VideoSoap affects image quality, we took the following screen shots with the noted VideoSoap settings. The first set of screen shots were taken using the recommend settings noted, while the second batch show each of the four filters applied to their maximum amount. The left side of each screen shot shows the video stream with VideoSoap enabled, while the right half shows the normal cable output. To further show the effects of VideoSoap, we used a channel that come in rather noisey in our location (turns out to be MSNBC). Be sure to click on the thumbnails to see exactly what is going on with each filter, as it is rather difficult to see in the small images on this page.

The images above should give you a good idea of what VideoSoap can do, which is make a noisey cable feed look quite a bit better. Although the channel used in the tests above was one of the more noisey ones in our cable network, the filters actually ended up making a noticeable difference in channels that looked to be clear for the most part.

We found that the VideoSoap setting of "medium" worked well in most situations as a sort of set it and forget it setting. We did have to be careful as to how much of a filter we applied. Using the filters too intensely can have a negative effect. For example, check out the screen shot below. This picture was taken off a fairly good quality feed with the combo 2 filter set to 100%. As you can see, there is quite a bit of detail loss on the left side that has VideoSoap applied, enough so that text could not be read clearly and edges looked blurred. In the image below, note the steps on the left side, the actor's face, and the tent in the background to see the detail lost.


VideoSoap: too soft focus

It takes some tweaking to find the best VideoSoap setting for each instance but it is fairly easy to do by using the preview window which updates in real time as the VideoSoap settings are altered. As a fail safe recording method, one can always just leave VideoSoap to low or medium with fairly constant results.

Obviously, the quality of your cable feed determines how much of a difference VideoSoap will make. Users who have digital cable or satellite cable should have much cleaner signals and therefore have less need for VideoSoap's filtering algorithms.

A positive side effect to VideoSoap's algorithms is that by reducing the noise of a video stream MPEG compression can occur more efficiently. We spoke about this in our preview as well but were left wondering then how much of a difference a cleaner video stream would have on compression. To find out we recorded the file sizes of 5 minutes of captured video at a number of settings. The results are shown in the table below.

With VideoSoap "Heavy"
Without VideoSoap
MPEG-2 (8M Bit/s constant, 224K Bit/s audio)
289MB
298MB
MPEG-2 (8M Bit/s max, 4M Bit/s target, 224K Bit/s audio)
150MB
151MB
MPEG-2 (400K Bit/s constant, 128K Bit/s audio)
21.0MB
24.2MB

The table shows that using VideoSoap does, in fact, make MPEG-2 videos more compressed in size. Because compression algorithms make use of patterns in a video, the random noise present in many cable feeds cannot be compressed. By taking out the noise, VideoSoap allows for more compression. By far the largest difference in size occurred at low bit rates. When we set the All-in-Wonder to capture at a constant 400K Bit/s rate, file size decreased by 15%. This makes sense, since it is at these low bit rates that the MPEG-2 algorithm is working the hardest to compress the video.

The file sizes above were from video captured from a fairly noisey channel on our cable provider. Moving from this channel to a cleaner one did decrease the effect that VideoSoap had on the file size. In this situation, the file sizes between the VideoSoaped capture and the non-VideoSoaped one was only about 1% (0.2MB) with the video captured at a constant bit rate of 400K Bit/s.

The Cobra Engine Theater 200 & Component Output
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