MJPEG vs. H.264By: John Honovich, Published on Apr 17, 2009
Recently, IQinVision releaed an article advocating benefits of MJPEG.
[Update Dec 2010: We conducted extensive testing comparing MJPEG and H.264. Read our Test Results of MJPEG vs H.264.]
While I found the article technically accurate, well written and worth reading, the nature of the application and its economics demand that MJPEG be almost always avoided. Since H.264 is hot right now, this is a popular claim to make. However, a discussion of this can help examine the economics and operational drivers driving this interest.
Jason's central claims are:
1. With moving cameras or images of high activity areas, MPEG4 and H.264 provide little bandwidth savings relative to MJPEG.
2. Proper network design requires factoring in worse case scenarios so you will need to dedicate the same amount of bandwidth whether or not you use MJPEG, MPEG4 or H.264.
3. MJPEG provides higher quality because of no intra-frame compression.
4. Unlike MJPEG, with MPEG-4 vendors deviate from standards, increasing potential integation costs.
My counterpoints are:
1. For most users, cameras usually have low or modest activity, translating into significant savings for MPEG-4 or H.264. Most cameras in the world are fixed. Most cameras have significant periods during the day when there is little or no motion (nights, weekends, etc.) Even within PTZs, PTZs are often left at a home position, or iterate over a series of pre-sets stopping for 5 - 10 seconds each.
2. Many, perhaps most organizations, do not set network bandwidth budgets for worst case scenarios. Sometimes, organizations don't want to pay the money for the extra capacity but sometimes it can't be done due to constraints of reutilizing existing infrastructure (very common in wireless networks). In other words, organizations generally trade-off infrequent pixelization for immediate cost savings. Maybe this is 'objectively' wrong but this is common.
2a. Jason does not discuss storage but storage is a HUGE economic driver in the move away from MJPEG. I have had a number of occasions where my DVR/NVR with a 1TB hard drive was only recording for 13 days. Why? I had forgot we recently integrated just a few megapixel cameras using MJPEG. Let's say we can save 1 Mb/s by switching from MJPEG to MPEG4. Over a two month period, for one camera, that is 650 GBs. It would cost you $300 to $600 to add that much storage for each MJPEG camera.
3. As for quality, the difference in quality is usually close enough that most customers are ok with it, especially for the savings.
4. The issue with deviation from standards is generally a one-time cost/problem that can be amortized by the manufacturer over many different customers. In the larger scheme of things, it's mainly a nuisance.
In sum, then, the economics of reducing network and storage costs are usually very significant budgetary and operational factors that drive purchasing decisions. With megapixel manufacturers starting to announce H.264 support, it will be interesting to see what IQinVision does.
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