Tonight I was looking back at where Stage6 was at and noticed a video on the front page that happened to be also on Joost. I thought… let see how Stage6 video quality compare with Joost. After all, Joost is priding itself in providing very good video quality.
So I downloaded two Stage6 video and compared them to those on Joost:
Here is some background about both. Joost video have an average bit rate of approximately 750kbps. I am not 100% sure about this but it is probably about right. The two Stage6 video have approximately 1500kbps in average bit rate.
Joost is using h.264 video codec and Stage6 use DivX. h.264 is an Advance Video Codec that is known to encode a same video frame in half the bits for the same or better video quality in comparison with DivX.
So based on this at about half the bit rate one would expect Joost to equal Stage6 video quality.
This study show otherwise. Here are a few revealing frames:
Thanks to ImageShack for Free Image Hosting
Those frames where capture in full screen mode on a Mac at 1440×900 pixels resolution. Notice how Joost lack details and is much more blocky. Joost is also padding 16:9 content with black bars for proper display on 4:3 screens… which is totally useless for PC playback.
Mind you… this might be a restriction imposed by the source material provided to Joost. Those black bars might actually be helping Joost in this comparison since it’s video picture appear smaller… Imagine zooming Joost screen captures even more to match Stage6 size… those macro block and fuzzy areas would just look… humm… bigger and fuzzier
Joost should have at least matched the quality of Stage6 based on codec and bitrate used… but for some reason it look more like 2 to 3 times worst than it’s DivX competitor.
The difference is even more obvious during live playback as Joost video appear fuzzy and jumpy compared to Stage6 version. Joost actually appear to be missing video frames… like if the video was encoded at half the original frame rate. This need to be confirmed.
Let us hope that Joost can tune it’s encoding parameter to match competition’s video quality. Joost is still in beta so there is certainly room and time for improvement.
P.S.: For those wanting to do the live video comparison… get a Joost invitation using the link in the navigaton menu of this site
Aug 14 2007 Update:
I noticed many article refering to this post. I should point out that since it was written new information became available. It appear that Joost video is NOT 750kbps but closer to 390kbps. That is right, 390kbps. This can certainly explain the large amount of macro blocks. Note that Joost is also going to do VBR encoding at some point in the future. Therefore even at 390kbps the actual video quality should drastically go up.