Optimization Deployment: Verizon Wireless Optimizes Web & Video using Transcoding, Caching and Buffer Tuning

    

Verizon Wireless combined its fair-use policy announcement with a 2nd message saying that "We are implementing optimization and transcoding technologies in our network to transmit data files in a more efficient manner to allow available network capacity to benefit the greatest number of users" (see "Important Information about Verizon Wireless Data Plans and Features" - here).

The document refers to the following page on VZW site - "Explanation of Optimization Deployment" (here) that has further details about the optimization technologies used:

"Web/HTTP port 80 optimization: The process incorporates several optimization techniques that depend upon the specific type of content file.  Specifically, text files are compressed without any loss of information (“lossless”) and cached for subsequent end user requests.  Image files (PNG, JPEG, GIF formats, for example) are streamlined to remove colors or other data bits that would not be visible to the human eye, or to end users on a mobile device with limited display resolutions, thereby decreasing the size of the file, and also cached.  The output image file reflects “lossy” optimization because some data bits from the original file are lost in the optimization process"
"Video Optimization.  ..  Optimization only captures recorded video files and does not affect live streaming video, e.g., a video conference call.  Several optimization techniques are applied to video files: transcoding, caching, and buffer tuning.  All are agnostic as to the source or content of the video.

 Transcoding.  When preparing a video file for posting on a web site, the video originator must select a codec (compression/decompression format) for the file.  All codecs are “lossy” to some degree in the compression process in that they reduce the quality of the original video.  But, some codecs are more efficient than others.  Optimization transcodes video files from their source codecs to a more efficient codec, H.264.  If the requesting device cannot decode an H.264 file, the file is delivered in the input codec.  Also, if the input file codec is H.264, there will be little or no effect on the file from the processes described below.

Caching   When a video file is detected from the Internet stream, the system decodes the first few frames (8 KB) of the video.  Based on those frames, the system attempts to locate the video file in its video cache, and, if the file is not in the cache, it copies the video file, catalogs, optimizes and places it into the video cache.  (The system needs to look at the first few frames for the cataloging process because the same video may come to the network from different sources and would have different URLs and headers; so, the header information is insufficient to identify multiple copies of the same video.)  The caching process is the same regardless of the source or content of the video.

Buffer Tuning  .. Whenever the video is requested, it is delivered on a "just in time" basis.  That is, rather than the entire file being downloaded when requested, the video is downloaded on an as needed basis.  A sufficient amount of video would be delivered to fill the user’s buffer to start viewing, and the remainder would be delivered as needed in time for the viewer to see it without interrupting the flow, calculating the video bit-rate and the actual bandwidth available.  This progressive download achieves significant network savings if the viewer chooses not to view the entire video, and it conserves data usage that would count toward the end users’ data allowance, and may result in savings if the end user is on a pay-for-usage plan.  As with caching, the buffer tuning process is the same regardless of the source or content of the video.