Image Resolution
Remote Patrol allows you to choose a image size for the video input device. Video resolution is based on the image size (measured in pixels per inch) in conjunction with the compression ratio of the image. Generally, the smaller the resolution the better the capture performance and the less hard disk space used by the captured footage, however larger resolutions will result in better image detail.

If you are using an NTSC video source or a digital camera it will typically supply video as 640x480 or 320x240. If you are using a PAL video source it will typically supply video as 768x576, 752x576, 736x576, 704x576, or 352x288. In any case it is best to use either full size or half size - any sizes in between may cause scaling in software which uses processor time and reduces quality. The "image size" dropdown menu on your personal web server contains optimum sizes to use, including the maximum size available. Using sizes other than those listed in this menu may cause slower performance, or may not be supported by the device.

Image Compression
Images from surveillance cameras often have a high level of temporal redundancy because usually most of the image is constant and only a small portion is changing. Therefore the use of temporal compression will usually significantly decrease file sizes of captured video without significantly degrading quality.

Some codecs such as MPEG-4 support temporal compression. Depending on the content, video can have a high level of temporal redundancy, that is, very often one frame is similar to the last frame. Temporal compression exploits this redundancy to reduce the file size of the resulting video. Temporal compression works by using "key frames" at regular intervals, followed by several "delta frames". The key frames contain the complete video image; the delta frames contain only the portions of the image that have changed since the last key frame.

There are several video compression codecs available for you to choose from, including:

None
No compression - produces the highest quality video possible but with the largest file size. In almost every circumstance, high-quality JPEG is preferable because of the huge data sizes of uncompressed video files.

Photo JPEG
Produces high quality video and is fast to compress so performance with this codec is very good. JPEG is reasonably efficient in terms of file size, but not as efficient as MPEG-4. JPEG is quicker to compress than MPEG-4.

MPEG-4
Highly recommended: produces high quality video at low data rates. It is reasonably quick to compress and it is possible to get good performance on a fast G4 or G5 PowerMac computer. Produces the highest quality at the lowest file sizes out of all the standard QuickTime codecs (requires QuickTime 6 or later).

Still image JPEG compression for local capture
Here you can set the compression quality for saving still JPEG images to the hard drive.

Still image JPEG compression for email/FTP upload
Here you can set the compression quality for sending JPEG image by email or uploading them to an FTP server.

JPEG/MPEG-4 compression for video streaming
Here you can set the compression quality for video streaming through the web server.

Audio compression
There are several audio compression codecs available for you to choose from, including:

None
No compression - produces high quality with low processor usage. Since the data rate of audio is generally much lower than that of video, unless you need very small file sizes, no audio compression can be a good option. If you are not using audio compression, you may like to use a low sample rate and mono audio to minimise the data rate (these options are set independently for each device in the Audio Device Settings window available from the Camera Setup window).

Apple Lossless
This gives quality equal to no compression (since it is a lossless codec), at roughly half the data rate. The only disadvantage of using this codec is that is uses processor time to compress, but not as much processor time as MPEG-4 (AAC) audio.

AAC
This produces high quality audio at very low data rates.

Example of 320x240 Resolution at 50% compression:

To reduce bandwidth usage, Remote Patrol requires the use of this resolution when using our Remote Storage servers. 320x240 resolution is also useful in keeping the hard disk space usage to a minimum for archiving and/or for recording from less significant cameras.

Click on the image below to see an example of 640x480 High Resolution at 50% compression:

Because of high bandwidth usage, recording at high resolution usually requires local storage at the location where the cameras are installed. Off-site site storage is only feasible when recording from a limited number of cameras. 640x480 resolution is recommended when image quality is crucial.

Contact Remote Patrol with questions. Call us or e-mail us and we will assist you at 1.866.761.4321 or support@remotepatrol.tv.