Keeping with a standardised format makes dealing with the video much easier.
The rise in HD surveillance video has been pretty rapid, with new implementations appearing on a weekly basis. Considering my first mention of HD was only in December 2012, it is clear that all those extra pixels are coming thick and fast!
This latest implementation to pass through my hands is from from AverMedia. Although the footage is really easy to deal with, there are a few issues worth a mention.
Before I get onto the video files, it is worth highlighting a nasty little habit with DVR exports. Along with a folder containing the .dvr files (the video), there is a player (QPlayer.exe), the required .dll files, and then an executable named Instcodec. The alarm bells start to ring with any software that is going to alter my machine so before running anything, lets take a look inside this .exe.
It is a self extracting compressed folder, so using WinRar it’s possible to see what hides inside.
And there we have it, it’s a codec install script. The two xvid .dll files end up in the Windows/System32 folder and the codecset.exe logs them in the registry. When the Qplayer is selected, a command window opens and the instcodec.exe is run automatically without asking permission.
It’s worth identifying this type of software. The type that silently installs codecs, dll’s or filters without permission and that have the possibility to screw up a working system. If you do see something, and you want to attempt to run something without it opening the other unknown executables, a good tip is to rename them. I renamed the file to Instcodec.exe.RENAME. The main player ran fine with no new codecs added into my System32 folder.
Now that’s been dealt with, lets get back to the video!
Aver’s player interface has not changed much over the years which does make navigating around easy. The first thing to mention within the interface, is the Intelligent Search. A few different companies have started using this but most have it on their main network client and not within an exported player. They have either used something developed in house, or integrated with another developer, such as Briefcam. The method used here works on standard motion detection rather than content analysis. It allows you to select a specific area on screen such as a doorway and then it bookmarks those times when motion occurs.
Next is the segment and export buttons. I won’t dwell too much on these but basically they allow you to select a part and then export that section as either another .dvr file, an xvid .avi or an mpeg4 video with a .mpg extension. Both the xvid and mpeg4 transcode the footage and as such, can take a considerable amount of time. This time is dependant on the initial recording resolution. And here comes the good part!
There is really no need to use the time consuming built in transcoder. By running the usual video analysis tests it turns out that Aver have retained the h264 standard. FFprobe was used to obtain the details of the video. FFplay was used for a quick preview and then FFmpeg was used to wrap the video inside an avi container. As a jog to your memory…
ffprobe -show_format -show_streams -count_frames -pretty myfile.dvr > myfile.txt
ffprobe -show_frames -print_format xml myfile.dvr > myfile.xml
ffplay -f h264 myfile.dvr
ffmpeg -f h264 -i myfile.dvr -vcodec copy -fflags genpts -r 15 -f avi myfile.avi
It is a lot easier and quicker to just deal with the .dvr file in the first place. Each one is in a camera specific folder and there is one .dvr file for each hour of footage. Its a shame that they did not do the same with the .idx files for the time-code. Perhaps Aver could develop an .idx – .sub converter…… now that would be great!
The footage itself, in this example, had a recorded resolution of 1280 x 1024. The GOP structure mirrored that of the frame rate with 1 I frame and 14 P frames. This was static throughout with no sign of any variation.
Taking everything into consideration, the ability to analyze and deal with the native video out of the player is a huge bonus. This is especially important as the player window opens at 1024 x 768. The recorded footage is actually bigger than the player!
A great format to deal with, however I’m never satisfied! If Aver could only change their player to NOT install anything, and if they created a small index to subtitle converter, there would be a lot of happy video analysts!