JP2000222332A - Method and system for exchange coded proxy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device and system for dynamically adjusting an exchange coding parameter for increasing the merits of exchange coding. SOLUTION: An appropriating method is designated for processing network characteristics and the variety of the size of an image to be exchange-coded. Also, the trade-off of quality and size can be adjusted for each image or client 230 by an exchange coded proxy. An appropriate exchange coder selects a different parameter for each object for improving performance. Moreover, policy decision is operated by a general frame work under the consideration of valid band width, image contents and type, and user selection. Also, feedback related with the selection of the optimal coding parameter is generated for a user.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a browser proxy for converting image objects embedded in a document, and more generally to any proxy or proxy for processing MIME encapsulated objects and the World Wide Web. Regarding the gateway system.

[0002]

BACKGROUND OF THE INVENTION Transcoding proxies sometimes act as an intermediary between a web server and various client devices that are connected via properties and communication links. In general, transcoding proxies offer two main advantages: a dramatic reduction in download time on low bandwidth links and a separate adaptation of web data to client devices.

[0003] Mobile devices are often connected via a low-bandwidth or medium-bandwidth wireless modem link to view abundant web content such as images due to their very long download times. Necessity makes it cumbersome. In addition, the cost of such downloads is prohibitively high over paid wide area wireless networks. The transcoded web proxy can reduce the size of web data while retaining most of its semantic values. In many common web images, a 6-10X reduction in download time can be achieved without losing their intelligibility.

[0004] A second important advantage is that these intermediate proxies, although sometimes small and inflexible, tailor text and images individually for the many web-enabled mobile devices currently available. What you can do.
The capabilities of these mobile devices to receive, process, store and display web content vary. With the presence of various client devices, for Internet content publishers,
It is difficult to tailor the contents individually for each device. As a result, a running web proxy transcodes or modifies web content, thereby optimally adapting to the resolution, color depth, and size limitations of small screen devices, and reducing the size of stored data. Used to shrink to part of the original size.

A typical transcoded web proxy is:
This can be realized by adding a transcoding module in the HTTP proxy. A transcoding module is an input / output system that receives a data object (eg, an image or an HTML page) as input and converts it into a low resolution object (eg, a low quality image or a summary HTML page) according to a set of selection parameters. is there. These parameters are input to the transcoder, which determines the resolution loss and size reduction of the object. The following discussion mainly relates to image objects.

[0006] To maximize the benefits of transcoding, it is important to choose a quality versus size trade-off so that the highest quality image is transmitted within the delay tolerance specified by the user. . However, selecting an appropriate set of transcoding parameters is difficult. First
In addition, it is difficult to estimate the size of the transcoded image. This is because the degree of compression achieved through transcoding depends on the content. For example,
Some JPEG files can be compressed up to 80%, while others achieve less than 5% compression. The same is true for GIF-GIF conversion or GIF-J
The same is true when PEG conversion is applied. Since transcoding is a computationally intensive process, processing is only worthwhile if high compression ratios can be achieved. For already highly compressed (or low quality) images, transcoding is useless.

[0007] Even though the size of the transcoded output can be predicted, network variability makes it difficult to predict the download time of the image. Since the quality and latency as perceived by the user are the ultimate performance indicators, an accurate estimation of the download time is required to select the optimal point of the quality versus size trade-off. On best service networks such as the Internet, it is difficult to calculate accurate estimates of network characteristics (bandwidth, delay, loss rate). Often, the variance becomes so large that the statistical estimates are meaningless in performing quality adjustments.

Another problem that makes policy decisions a complex task is the location of bottlenecks in the network. If the path between the web server and the proxy is a bottleneck, transcoding is useless at all. On the contrary, the nature of the store-and-forward nature of the operation exacerbates the situation. Ideally, the web server
If the path to the proxy is a bottleneck, the web proxy should always transfer the image from the web server to the client. Even if the proxy-to-client path is a bottleneck, the benefits of size reduction must be weighted against the store-and-forward delay caused by transcoding.

Due to the difficulty in estimating network characteristics and image content, transcoding proxies often
It only supports adaptation at a very coarse level. Adaptation typically involves changing transcoding parameters selected from a predefined set of default values or selected by the user. The problem with both approaches is that the full potential of transcoding is not exploited. Predefined static policies do not respond to changes in network bandwidth, and user-selectable policy decisions tend to be suboptimal due to a lack of knowledge about the state of the network. There is no way to provide feedback to the user about the connection status of the network and the proxy. By using iterative refinement, the user can converge towards an optimal choice of transcoding parameters, but such a process is time consuming and not very user friendly.

FIG. 1 shows an example of a transcoding proxy situation 100 with various links and various client devices. As shown in FIG. 1, here, client 1
All web requests and responses for 30-134
Consider a situation where the transfer is via a generic HTTP (hypertext transfer protocol) proxy 190.
In the situation of FIG. 1, downloading a large data object, primarily an image, from the proxy to the client via the last link 160-164 is primarily due to the end-to-end response time delay experienced by the client 130-134. That is the cause.

[0011] The transcoding proxy 190 provides bulk data decimation of web data and enables real-time browsing of web data over low-speed wide-area wireless links. These wireless links have 10 depending on the number of clients sharing the link.
Includes Cellular Digital Packet Data (CDPD) 163 that provides kb / sec or less throughput. The terminating client is, for example, a full function PC 134 with a good color display, so the main problem is bandwidth reduction. Alternatively, the client is a small web-enabled mobile device 130-132, in which case it is advantageous to tailor the web data individually for a particular client device, especially for the client's display device characteristics. It is. Different aspects of the transcoding proxy design are different in different situations (ie, pay proxy-
All are well served within the same proxy architecture 100, although useful for client-to-client links or strong or poor client displays.

FIG. 2 shows a block diagram of an embodiment of a transcoding proxy 190 used to transform objects based on user-specified selections and static policies.
The transcoding proxy 190 uses the transcoding module 2
40 and the HTTP proxy engine 220. An HTTP request 222 is generated from client 230 and forwarded by proxy 190 to web server 210 (224). Response data 226 (ie, HTML page and GIF and JPE
G image) is converted by the transcoder 240 and transferred to the client 230 (228). In general, a number of transcoding parameters are specified for transcoder 240 to achieve the desired quality and size reduction of the objects contained in response data 226. Transcoding proxies used today determine transcoding parameters by using a static policy set 250 or by using a particular form of user-specified selection 260 via path 265. When a fixed set of transcoding parameters is applied to all objects, the results are not always advantageous. In fact, transcoding often results in performance degradation.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method, apparatus and system for dynamically adjusting transcoding parameters so as to increase the benefits of transcoding. An adaptation method is designed to handle the variability in network characteristics and size of the transcoded image.

[0014]

SUMMARY OF THE INVENTION In one embodiment, the present invention provides three new elements: an image size estimator;
Includes a network bandwidth analyzer and a policy module. Before commencing transcoding activity, the policy module queries the image size estimator to estimate the size of the output image. The bandwidth analyzer is queried to collect an estimate of the image transmission time from the server to the proxy and from the proxy to the client. Based on the collected estimates, the proxy decides whether to transcode the image. In addition, the policy module calculates an optimal point of quality versus size trade-off that provides a user-specified performance criterion (eg, reduced response time, or improved quality).

Another aspect of the present invention provides a method and apparatus that allows a transcoding proxy to adjust the quality versus size trade-off on a per-image or per-client basis. An adaptive transcoder selects different parameters for each object to provide a performance improvement.

Still another aspect of the present invention is to account for effective bandwidth, image content and type, and user selection.
Provides a general-purpose framework for making policy decisions. The proxy administrator selects among various optimization goals to obtain improved performance from the system. In one embodiment, if the throughput of the proxy transcoder is a bottleneck, the policy module is wisely instructed to use CPU resources to reduce response time for all users. An advantageous element of the present invention is the automated nature of policy decisions, relieving the user from active control of the proxy policy engine.

In yet another aspect of the invention, a method is provided for generating feedback to a user regarding the selection of optimal transcoding parameters. In one embodiment, the transcoding system provides feedback to the user by dynamically adjusting the position of the user-selected slider bar. The user-selected slider bar acts as both an input device and an output device.

[0018]

FIG. 3 is a block diagram of an embodiment of a modification to transcoding proxy 190 in accordance with the present invention.
00 is shown. Comparing FIG. 3 with FIG. 2, it can be seen that the static policy module 250 of FIG. 2 has been replaced by a dynamic policy module 370 in FIG. The purpose of the dynamic policy module 370 is to determine when to turn transcoding on / off and what transcoding policy to use (ie, the transcoding algorithm and its parameters). The dynamic policy module 370 also
Image size and delay estimator 375, bandwidth estimator 380, and user feedback provider 39
Interface with 0. In the illustrated embodiment, the policy
Module 370 uses a number of criteria: 1. 1. Characteristics of the data determined by the content analysis flow diagram (shown in FIG. 5) (eg, image size, current coding efficiency, structural role of HTML page) 2. A current estimate of the bandwidth of the proxy-client link and the server-proxy link. 3. Client characteristics, especially client display capabilities. User selection for preferred rendering of data (illustrated as user slide bar selection in FIG. 11)

The items shown in FIGS. 5, 10 and 11 are described below. In particular, the user slide bar selection of FIG. 11 provides a way to interact with the transcoding proxy and dynamically change the tradeoff between image quality and download time. In addition to acting as an input interface, a slide bar (114 in FIG. 11)
0, 1150, 1160) also serve as output interfaces and display feedback 390 received from dynamic policy module 370.

FIG. 4 shows a transcoded HTTP according to the invention.
FIG. 4 is a block diagram showing an example of a function of a multi-resolution cache 410 in the proxy system 400. Caches are useful in HTTP proxies to provide reduced response times for repeated data requests (by the same or different clients) for the same data object. Various methods may be used to ensure that cached data is up to date. In the example cache-based transcoding system 400, the multi-resolution cache 410 may include, in addition to the original version of the data, other possible types of reduced resolution versions transcoded for a particular device type. Store the data.

For example, again considering the case of image data objects, those skilled in the art will recognize that these methods can be applied to other data types. This section describes how to store, tag, and retrieve various types of data in the context of a cached transcoding proxy system.

Referring to FIG. 4, in response to a request by client 230, a JPEG image is
Is assumed. The image is decoded from a lossy JPEG encoding format to a bitmap representation of the image. For those skilled in the art of image processing, the JPEG coding standard defines the discrete cosine transform (DC
It will be appreciated that a computationally intensive decoding step is generally required to describe the image using coefficients that weight Discrete Cosine Transforms (T) and thus obtain the actual color of each pixel. This bitmap requires a larger storage size than the original JPEG image. However, if a sufficiently sized cache is provided, it is worth storing this extended size image (via data path 420). Thereby, a transcoded version of the same image is later
The computationally intensive steps for JPEG decoding can be avoided when required by different transcoding parameters than the initial request. In a second step, the JPEG image is re-encoded based on transcoding parameters (eg, color depth, scaling factor, and JPEG quality factor). The image is re-encoded as a JPEG image or in another encoding format. The last transcoded version of the image is also in data path 4
20 and is stored in the multi-resolution cache 410.

In an embodiment, when an additional data request occurs, the HTTP proxy 220 first checks its cache 410 and determines whether the "latest" version of the data object is at the requested resolution or transcoding level. Check if it is available. Each object in multi-resolution cache 410 is stored with a URL designator, a time stamp of the data object, and a version specifier that includes object characteristics. JP
For EG images, object properties include color depth, scaling factor, and JPEG quality factor. Other embodiments have an indication that the JPEG image has been decoded and stored in its bitmap format, or that the JPEG image has been converted and stored as various GIFs with various characteristics.

If the latest version of the object with the requested type and resolution is available, that version is returned to the client. If this is not available, but the latest version of the object exists in its original JPEG or decoded bitmap format, this version is returned to transcoder 240 with an indication of its properties. This allows transform encoder 240 to generate the desired version of the object, which is returned to client 230 and stored in multi-resolution cache 410 via data path 420.

There are several extensions to this mechanism that will be apparent to those skilled in the art. Some extensions use an already transcoded version of the object, rather than the original data object, to generate a reduced resolution version of the object. How to manage different resolution versions of data objects in the cache
R. O. LaMaire and J.M. T. 1998 by Robinson
U.S. Patent Application No. 102944 "Conserv.
ing Storage Spase by Means of Low Resolution Objec
ts "(Applicant's Reference Number: YO997308).

FIG. 5 shows an example of a flow diagram of the dynamic policy module 370 of FIGS. FIG. 5 also shows how the policy module 370 interfaces with the HTTP proxy engine 220 and the object transcoder 240 of FIG. The methods described below use text,
This is true for many content types, including images, audio and video. However, the following discussion focuses only on the image data type. However, it will be apparent to one skilled in the art that this concept and dynamic policy are applicable to other media types.

FIG. 5 shows the HTTP proxy engine 220 based on the response header received from the server 210.
First determine the size of the object 510. If the content type of the response is "image / *" (step 520), the proxy engine 220 passes the handle of the object to the dynamic policy module 370 for further analysis. Within the policy module 370, the size of the input object is compared to a pre-configured threshold called "size_threshold" (step 530). If the object is smaller than "size_threshold" or the content type is not "image / *" (step 520), the object is not transcoded and instead transferred to the client without content change (step 5).
15). Small objects (bullets, thumbnails, logos, etc.) found on the web are generally GIF objects already well compressed by GIF coding. Transcoding of such objects generally does not produce any further compression.

Here, the GIF image is converted into a GIF or JPEG image reduced in size or color depth (GIF or JPEG as the final format).
Selection depends on image characteristics). Further, the JPEG image is converted into a JPEG image with reduced JPEG quality, size, or color depth. JPEG quality refers to transcoding parameters used to determine the degree to which the discrete cosine transform coefficients used in the JPEG coding standard are quantized. The JPEG quality parameter has also been found to be a good predictor of perceived image quality. This parameter is 1 to 1
It varies within the range of 00, with 100 representing very high quality. JPEG images found on the web typically have 75 JPEG quality parameters.

For large images, the type of image encoding (JPEG or GIF) and the efficiency of the encoding are:
It is an important factor in transcoding strategy decisions.
Since JPEG is a lossy compression method, size reduction is always possible by reducing the quality factor. However, a similar degradation is not applicable to GIF files. This is because GIF is a lossless compression method. To achieve quality degradation, the GIF file must first be decoded and then re-encoded as a quality degraded JPEG image. However,
This method does not always provide a reduction in size.
The GIF format is usually more efficient for encoding maps, logos, and figures, while JPEG is more efficient for encoding natural pictures. GIF to JP
Conversion to EG is only useful if the original GIF image is not efficiently encoded.

Here, the number of bits per pixel (bpp: bit per pixel) is defined as an index of the compression efficiency.
bbp is an image file for the image area.
The size ratio is calculated in units of pixels. At processing step 540, the X and Y dimensions and bpp values of the input image are calculated by analyzing the image header. If the input object is of type "image / jpg" (step 550), transcoding is always performed. However, if the content type is "image / gif" (step 525), b greater than "gif_threshold"
Only objects that produce a pp ratio are transcoded (step 535). GIF files are not very efficiently encoded, producing bpp values greater than "gif_threshold". Therefore, the decision step 535 is very effective in identifying compressible GIF files with high accuracy. Although not shown in FIG. 5,
It will be apparent that other transcoding policies can also be used for fully compressed GIFs, such as scaling (for progressively encoded data) and file truncation.

An important aspect of the invention is that the decision step 51
0-565 is to be performed as soon as the image header is received. If it is determined not to transcode, the image segments are transferred as soon as they are received from the server without incurring store-and-forward delays. Similarly, if transcoding is performed, the image is buffered and subsequently transcoded (store-and-forward transcoding) or each segment is transcoded on the fly (stream transcoding). Encoding method).

After identifying the compressible image, the next step is to determine the degree to which the selected image should be transcoded. The policy function 565 collects inputs from three different sources (image size estimator 375, bandwidth estimator 380, user selection selector 260) and then follows FIG.
And serves to select the transcoding parameters. The selected parameters determine the degree and type of compression performed by the object transcoder 240. For example, a scaling parameter determines how much an image is downsampled. The quantization parameters control how the image is quantized in the pixel domain or the frequency domain. The number of colors in the color-mapped image may be reduced, or a 24-bit color image may be converted to an 8-bit grayscale or monochrome representation. The transcoding process is performed in step 570, where the output of the transcoder is forwarded to client 230.

An important aspect of the policy function 565 is an analysis framework for determining transcoding strategies. The analysis framework considers factors such as available bandwidth, image type and size, user selection, and provides target criteria for determining transcoding policies. For example, although the goal here is to minimize response time for the user, those skilled in the art will recognize that other optimization criteria may be applied using the same framework. Here, when it is advantageous to transcode,
It also describes how to determine to what extent transcoding should be applied. The embodiment described here is
This is called dynamic adaptation of transcoding parameters.

FIG. 6 shows an example web request-response cycle and response time for fetching an object of size S via store-and-forward transcoding proxy 190. Here we define a store-and-forward image transcoder as an image transcoder, which must wait for the entire input image to be stored before commencing transcoding on the image, and Before is ready for output
One has to wait to generate the entire transcoded image. As shown in FIG. 6, the size S (bytes)
The original image 620 at 670 is the effective bandwidth B
Through _sp (bits / sec) server-proxy connection,
Downloaded to store-and-forward proxy. The transcoder introduces a delay D _x (S) 650 and a size S _x (S) 680
Generates an output image 630. Transcoding delay 65
Both 0 and the byte size 680 of the output image are
It is represented depending on the byte size S670 of the input image. The transcoded image is then transmitted over a proxy-client connection having an effective bandwidth B _pc .

The policy function needs to weight the cost (delay) of transcoding for any size reduction achieved by transcoding. In order for transcoding to provide benefits, the delay introduced by transcoding must be offset by the reduced transmission time due to compression. For very low bandwidth proxy-client access links, the reduction in response time due to aggressive image compression generally outweighs the additional response time due to computationally intensive transcoding. However, FIG.
Indicates that as the bandwidth of the proxy-client link increases, a point is reached at which transcoding is no longer advantageous (transcoding threshold 710). This is because the reduction in response time due to aggressive compression decreases as a function of the bottleneck link bandwidth, but the transcoding time remains constant.

Here, R _o is the response time for fetching a web object of size S from the web server when transcoding is off. Similarly, R _p is the transcoded version of the same web object,
The response time to fetch through the transcoding proxy. For the following discussion, it is assumed here that caching is not supported at the proxy.

When transcoding is off, the response time sensed by the client is the sum of the following three terms:

R _o = 2RTT _pc + 2RTT _sp + S / min (B _pc , B _sp )

RTT _pc is the network round trip latency between the client and the proxy, and similarly RTT _sp is the latency between the proxy and the server. Web object fetching, in addition to HTTP requests / responses,
2RTT _pc + 2R because it requires SYN / ACK exchange
TT _sp contributes as a delay term. Further, a web image introduces a transmission delay equal to the spread of time between its first and last bits. Where min (B _pc , B _sp )
Indicates the bottleneck bandwidth between the client and the server. If no proxy is present, the first and last bits of the image are spread out in time by S / min (B _pc , B _sp ). This spread corresponds to the effective transmission time of the image via the server-proxy-client connection.

When transcoding is on, the proxy stores
Operate in product transfer mode. 2RTT _pc+ 2RTT_spBut again
Degree is a fixed factor of response time. D_p(S) is a commutation mark
It is an additional term representing the encryption delay. Transcoding object
The response time of the result in the test is expressed as follows.

## EQU2 ## R _p = 2RTT _pc + 2RTT _sp + D _p (S) + S
_{/ B sp + S p (S} ) / B pc

When R _p <R _o , that is, when the following equation holds, transcoding reduces the response time.

D _p (S) + S / B _sp + S _p (S) / B _pc <s /
min (B _pc , B _sp )

[0041] Clearly, in the case of the B _pc> B _sp, R _p is always greater than R _o. On the other hand, if B _pc <B _sp , then _transcoding is useful only if:

D _p (S) + S / B _sp <(S−S _p (S)) / B _pc

The above equation exactly characterizes the situation where transcoding reduces the response time. FIG. 8 shows a flow diagram of a policy function configured using the above-described analysis framework. Step 810 describes the entry point of the policy function. The policy function 800 is called in step 565 of FIG. 5, where the original image object size is selected as one of the inputs to the policy function. The variable S is set equal to the input object size, and the quality factor q is initialized to the best possible initial image quality (eg, the quality of the input image). At step 830, the policy function 800 issues a query to the bandwidth estimator 380, asking for the estimated download time of the object size S from the designated server to the proxy, ie, T ₁ (S). The policy function 800 also queries the estimated download time of the same object from the proxy to the client, ie, T ₂ (S). Based on the log of previous connections to the selected destination, the bandwidth estimator
Return the estimated values of ₁ (S) and T ₂ (S). In the next step 840, the policy function provides the image size and delay predictor 375 with the transcoded image size _Sp (S).
Query to find an estimate of. The policy function then in step 850, T ₂ from (S), the download time estimates of exchange coded image size T ₂ (S
Calculate the estimated download time savings by subtracting _p (S)). Finally, in step 870, the two quantities (exchange coding delay + T ₁ (S) - Download savings), and the target response time reduction is compared. If the first term is smaller than the second term, the calculation is stopped at step 880 and the selected quality factor q is returned as output. Otherwise, the q value is reduced and re-entered in loops 840-870.

According to those skilled in the art, more efficient search techniques or variants of the objective function could be designed without departing from the spirit of the policy function framework provided in the present invention. One extension is to rearrange the terms in the policy equation as follows:

## EQU5 ## Response time reduction (q) = {S−S _p (S)} / B
_pc −D _p (S) −S / B _sp

In the above equation, S _p (S) is also a function of the quality factor (the smaller the output size, the lower the quality). It has been found that transcoding delay is practically independent of the quality factor. In the above equation there are two independent variables,
That is, there is a quality factor q and a target response time reduction.
Within the framework of the above equation, several different policies can be generated. They are, for example, policies that minimize response time for all users, and policies that maximize quality in user-specified response time limits, as well as optimizing overall system performance, not just for one user. Policy.

Transcoding is a computationally intensive task,
Because only the proxy limited CPU power, the CPU cycles of the proxy were spent on a set of tasks that maximized overall user satisfaction. During peak usage periods, if every user turns on transcoding, enough CPU cycles may not be available to satisfy all transcoding requests. By delegating responsibility for parameter selection to the policy function 800, the system can automatically select the optimal transcoding parameters and provide a consistent and predictable response to the end user. If the user selects these parameters independently, the transcoding system will not be able to operate at the optimal performance level.

Next, let us consider transcoding delay and size estimation. Decision step 870 requires two additional inputs: an estimate of the transcoded image size _Sp (S), and a transcoding delay _Dp (S) introduced during the transcoding process. . Accurate predictions of these two quantities are difficult to obtain. Because they depend on the image content, the type of encoding used, the original quality factor, the processor speed, and the load on the proxy. As with the bandwidth estimator, the present invention uses statistical methods to estimate these two quantities.

FIG. 9 is a block diagram of an example of an image size prediction module according to the present invention. Block 910
Here, the system is initialized with the statistical properties of S _x (q) based on a large set of benchmarks of the image. The method shown at block 910 is used to initialize a transcoded image size distribution function that depends on the parameters bpp and q. As the proxy fetches and transcodes new image objects, it frequently adds new sample points to the distribution function (block 920). The function of block 920 allows the image size predictor 375 to adapt its behavior to different data sets that the client may be accessing.

Thus, in the method described at block 930, the delay and output size are estimated by statistical methods and the bpp ratio is used to perform a more accurate classification of the image, and thus the resulting transcoded file size. Is used as a criterion to form a better estimate of. This method works especially well for GIF files.

By using a similar statistical method,
D _p (S) can be estimated based on benchmark initialization and online updates of the statistical model. Statistical work has also shown that transcoding delay is well characterized as a linear function of the number of pixels (rather than the file size).

Next, consider bandwidth and download time estimation. The accuracy of decision step 870 also depends greatly on the accuracy of the image download time estimate. The bandwidth estimator 380 shown in FIGS.
You are responsible for providing these time estimates. Bandwidth estimator 380 records any packet transmission / reception events at the proxy, performs statistical analysis on the collected traces, and makes decisions regarding network conditions. Those skilled in the art of network monitoring will appreciate that the network monitoring functionality may be implemented in several different ways. One technique is proxy
A shim layer between the application and the socket layer
r). Another technique is a processing layer on any packet filtering software. In general, techniques implemented on packet filtering software provide more accurate estimates of bandwidth and download time. The present invention does not require that both the bandwidth monitor 380 and the policy decision step 870 be performed on the same machine, but placing the two modules together adds communication overhead between them. Minimize.

FIG. 10 shows an example of a bandwidth prediction module 380 according to the present invention. This module consists of two components: a trace monitor 1010 and a statistical analyzer 1020. The trace monitor continuously monitors all connections between the client and the proxy. The same trace monitor (or another trace monitor)
Is used to monitor traffic between the proxy and all web servers. The following information is recorded for each connection monitored. Time when new connection is established Source address, source port number,
And destination address, destination port number The number of bytes sent and received on each connection, and the timestamp of each sent and received event The time when the connection is closed

The statistical analyzer 1020 maintains a database of all past and current activity connections. For each connection, the statistical analyzer also keeps a history of when and how many bytes were sent or received on that connection. Based on this history, statistical analyzer 1020 can make predictions about the download time of future connections. Download time from server to proxy,
And different heuristics to estimate the download time from the proxy to the client.

The trace from the server to the proxy shows the general behavior between wide area TCP connections. The sequence vs. timestamp trace is observed to be non-linear, and the concept of linear prediction, such as average or center bandwidth, is
It has been found that it does not produce accurate predictions. To predict the download time of an object of a given size, the bandwidth estimator looks up the history of the connection to the selected destination and calculates the distribution function of the download time for all objects having approximately the same size. calculate.
The median of this distribution or other suitable statistical function is returned as the download time estimate.

In contrast, the TCP behavior between the proxy and the client is generally the last hop 160-1.
With the effect of having a bandwidth limited link equal to 64,
Ruled. Since there is a bottleneck link, the aggregate of all active TCP connections to the client will generally saturate the bottleneck link. Thus, to provide a proxy-to-client download time estimate, the bandwidth estimator aggregates all active connections to the client into a single group. For each connection group, the bandwidth estimator plots time versus number of bytes, and then performs a linear curve fit on the data. This technique provides an accurate estimate of the currently available bandwidth between the proxy and the client. This value changes over time, but the variability is limited in most cases. For example, the bandwidth monitor can easily detect whether the client is connected by a 10 Mb Ethernet, 14.4 or 28.8 modem by analyzing at the output of the curve approximation algorithm. Although the predictions are not accurate (with a deviation of 20% to 30% from the exact values), those skilled in the art will appreciate that the accuracy of the bandwidth estimation can be improved by improving the estimation algorithm. Like.

Next, consider the transcoding user interface. The transcoding user interface is an interface for the user to dynamically change the tradeoff between image quality and download time. This is represented as item 260 in FIGS. FIG. 11 shows an embodiment of the user selection interface according to the present invention. This user interface is represented as a linear slide bar, which can be implemented as a Java applet, allowing the user to continuously change the image quality. As shown in FIG. 11, an option to select a color (for grayscale) is also provided. Further, the option to select an autopilot can also be used in two ways: That is, (1) as described above, the proxy is
As an indication to inform the proxy that it can automatically determine whether to perform transcoding based on the current prediction of the inter-proxy and proxy-server link bandwidth and the currently available CPU resources, or (2) As an indication to tell the proxy to try and maintain the current download time the user is currently experiencing (ie,
By changing the image quality at the proxy,
Compensating for dynamic bandwidth changes detected by the bandwidth estimation subsystem), or as both (1) and (2) above. When users request a full-fidelity data version, they can easily request improved data by adjusting the slide bar (downward) and requesting higher quality data. In general, almost all web browsing is performed by transcoding images to one-sixth or one-tenth of their original size, and objects such as maps that need to be refined are: In practice it turned out to be rarely found. It should also be noted that another HTML-only interface has been devised to support non-Java devices, such as Windows CE based platforms.

Next, stream type image transcoding will be described. The above description generally applies to store-and-forward transcoding proxies. The following describes the conditions under which it is advantageous for a stream-based image transcoder to engage in transcoding. The stream image transcoder starts writing out the image data encoded in the output format before completely reading the complete input stream bytes corresponding to the entire image encoded in the input format. An image transcoder.

FIG. 12 illustrates the rationale behind the algorithm with a timing diagram. The input image is 1 / B
arrives as a bit stream spaced by _sp .
A streamed image transcoder receives a group of G bits for transcoding and has a small store-and-forward delay D
Yields ₁ . The bit groups are then transcoded into groups of G _p output bits, resulting in a delay D ₂ . D ₂ <D ₁
, The image transcoder can convert each input group G into its corresponding output group G _p before the next input group G needs to be processed. In this case, the internal memory requirements of the stream image transcoder are limited. However, if D ₂ > D ₁ , the image transcoder cannot process the input bits fast enough. In this latter case, the internal memory requirements of the image transcoder grow without limit when a continuous input stream is provided. That is, the finite length internal RAM buffer of the image transcoder overflows. Therefore, it is desired that the transcoding delay D ₂ satisfies D ₂ <D ₁ . Obviously, D ₁ = G / B _sp . In order to find the D _2,
Let D _p (S) be the predicted image transcoding time for an S-bit image (D _p (S) actually depends on other parameters, such as image content and dimensions, but here the notational simplification Therefore, D _p (S) is used). Therefore,
D ₂ = D _p (S) / (S / G) To avoid RAM buffer overflow, the group transcoding delay must satisfy D _p (S) / (S / G) <G / B _sp , or:

D _p (S) <S / B _sp (condition A)

Assuming that condition A remains true, the output
Transcoding group G_pIs D₁Uniform with a delay equal to
Can be spaced apart. The transmission channel is
Group G_pAnd time D_Three= G_p/ B_pcSend in
be able to. Case (i), ie, D_Three(I) <D₁so
Is the output group G_pBut the next output group is
It can be sent before it is ready. Case (ii)
Chi D_Three(Ii)> D₁In, the output transmission link is the generated bit
Should be sent fast enough to keep the output queue empty.
I can't do that. In case (ii), the transcoded bits
Output of the transmission link if a continuous stream of
The queue grows without limit and the finite length link buffer
An overflow occurs. Therefore, the transcoded output glue
The delay caused by the loop size is D_Three(I) <
D₁It is desired that Obviously, D_Three(I) = G
_p/ B_pcIt is. Overflow of output buffer of transmission link
To avoid rows, use transcoded output image
Loop size G_pIs G_p/ B _pc<G / B_spOr
Must be satisfied.

Γ> B _sp / B _pc (condition B)

Where γ = group image compression ratio G
/ G_pWhich is, on average, the overall image compression
Assume that it is equivalent to the rate. In short, stream type
The image transcoder satisfies both condition A and condition B.
Transcoding should be performed only if Professional
If the link between the xy-server is a bottleneck,
B_cp<B_pc, The condition B is reduced to γ> N. here
And N is a number less than 1. Usually, the compression ratio is always
large. Therefore, the condition B is always satisfied. in this case,
Only condition A is satisfied so that transcoding is not disadvantageous
It must be. In fact, the proxy-server link
Condition B is a transcoded image if
Expansion ratio, ie, 1 / γ <B_pc/ B
_spTo be provided. Image enhancement
For example, from GIF to Palm format
When format conversion is forced, such as when converting
Sometimes needed. The above equation describes these format changes.
If the exchange increases the chance of buffer overflow, and
If the format conversion does not cause a buffer overflow
To make decisions. For example, B_sp= 1 bps, B_pc
= 2 bps and G = 1 bit, condition B is output
Group G_pCan be extended to a maximum of 2 bits.
Client-proxy link is a bottleneck,
Wachi B_sp> B _pcIn the case of Condition B, transcoding is valuable.
In order for the image compression ratio γ to be
Ratio of proxy-server bandwidth to proxy bandwidth
Indicates that it must be larger than In addition,
Case A must still be satisfied.

Conditions A and B are strict restrictions that the buffer must never be allowed to overflow. One of ordinary skill in the art will appreciate that assuming that the image is not a continuous stream as assumed in the analysis, but a finite length, relaxed constraints can be derived. More relaxed restrictions allow more time for transcoding and allow for less active computation.

Accordingly, one aspect of the present invention is to provide a method for a transcoding proxy that facilitates browsing between a client device and a server connected via a communication network. The method comprises receiving, from a client device, an HTTP get (GET) request for an object stored on one of the servers;
Forwarding an acquisition request for the object to the server, receiving the object from the server, examining a selection specified by a user of the client device, examining the content of the object, and examining communication network characteristics. And selecting a set of transcoding parameters; forming a transcoding format of the object; and transmitting the transcoding format to the client. Investigating network characteristics includes estimating a network bandwidth between the server and the proxy and between the proxy and the client; estimating a delay between the server and the proxy and a delay between the proxy and the client device; Providing feedback to the user regarding the level of transcoding performed on the object. The step of investigating includes determining the size of the object, determining the size of the object, and calculating the compression ratio of the object. If the object is of the image type, the dimensions of the image object are determined by the area of the image in square pixels, and the compression ratio is determined by the bpp ratio of the image object. The present invention allows for both store-and-forward and stream-based transcoding, thereby allowing the transcoding format to be formed before the step of receiving the object from the server is completed. This method is JP
It is also applicable to EG, GIF, and other image types. Another aspect of the invention allows the transcoding format to be sent out before the step of forming the transcoding format of the object is completed.

There are several other important considerations. The above examples of the inventive concept are common for images and videos and the like. The widespread use of the Internet has shown the value of JPEG and MPEG compressed image data. The audio coded data also needs to be decompressed, mixed with special sound effects, merged with other audio data, and edited and processed in the real world. Similar techniques are implemented in other industrial, commercial, and military applications.

[0063] The invention may also be provided as a process, product, apparatus, system, architecture, or computer product. For example, the invention may be implemented as an article of manufacture comprising a computer usable medium having computer readable program code means for instructing a computer to perform the method of the invention. Although the description of the invention has been described with reference to specific step configurations, the spirit and concept of the present invention is suitable and applicable to other configurations. For example, while the embodiments described herein relate only to web browsing, the present invention is applicable to any browser. The main emphasis was on dynamic techniques,
The invention can be used with a combination of static, semi-dynamic and dynamic techniques. It will be apparent to those skilled in the art that other modifications of the embodiments disclosed herein are possible without departing from the spirit and scope of the invention. Accordingly, all these variations and modifications are intended to be included within the scope of the present invention.

In summary, the following items are disclosed regarding the configuration of the present invention.

(1) A method for a transcoding proxy that facilitates browsing between a plurality of clients and a plurality of servers connected via a communication network, the method comprising: Receiving a request for an object stored on one of the servers; forwarding the request for the object to one of the servers; receiving the object from one of the servers; Examining a selection specified by one user of the device; examining the contents of the object; examining communication network characteristics; selecting a set of transcoding parameters; Forming a transcoded form; The method and transmitting the reduction format to one of said client device. (2) the network characteristics include bandwidth, and the step of examining the network characteristics estimates network bandwidth between one of the servers and the proxy and between the proxy and one of the client devices. The method according to the above (1), comprising a step. (3) the network characteristic includes a delay, and the step of examining the network characteristic includes estimating a delay between one of the servers and the proxy and a delay between the proxy and one of the client devices. The method according to (1) above. (4) The method of (1) above, comprising providing a user with feedback regarding the level of transcoding performed on the object to form the transcoding format. (5) The method according to (1), wherein the examining step includes determining a size of the object. (6) the object is an image type forming an image object, wherein the method includes determining dimensions of the image object; and calculating a compression ratio of the image object. (1) The method according to the above. (7) The method according to (6), wherein the size of the image object is determined by an area of the image formed by square pixels, and the compression ratio is determined by a bpp ratio of the image object. (8) The method according to (1), wherein the step of forming the transcoding format uses dynamic adaptation. (9) The method of (1), wherein the step of forming the transcoded form is started before the step of receiving the object from one of the servers is completed. (10) The type of the received object is JP
The method according to (9), wherein the EG object is a JPEG type. (11) The step of forming the transcoding format comprises:
Performing PEG-JPEG image transcoding, wherein transmitting the transcoded form comprises:
The method of claim 10, wherein writing of at least one MCU of JPEG encoded output image data is started before the object is completed. (12) The step of sending the transcoded form is started after processing an initial portion of the received object and before the step of receiving the image object from one of the servers is completed. 1) The method according to the above. (13) The method according to (1), wherein the step of transmitting the transcoding format is started before the step of forming the transcoding format of the object is completed. (14) A method for a proxy that forms a transcoded form of an object received from a server in response to a request from a client for an object available from a server, the method comprising: A method comprising dynamically adapting parameters for transcoding, forming a transcoding format of the object, and transmitting the transcoding format to the client. (15) The method of (14), wherein adapting the parameter comprises determining at least one property of the object. (16) The method of (15), wherein one of the characteristics is an object header that provides information about the size and type of the object. (17) Set the size of the object to "size_threshold"
The method according to (16), comprising comparing with a threshold parameter called. (18) The method of (14), wherein adapting the parameters comprises collecting current network characteristics between the server and the proxy and between the proxy and the client. (19) One of the characteristics is a network bandwidth;
The method of claim 18, wherein the adapting comprises estimating network bandwidth between the server and the proxy and between the proxy and the client. (20) The method according to (19), wherein the transcoding format depends on the estimated bandwidth. (21) The method of (14), wherein the adapting step comprises retrieving a user's selection, wherein the transcoding format depends on the selection. (22) The method according to (14), wherein the adapting step includes examining the contents of the object. (23) The method of (22), wherein the object is an image type forming an image object, and wherein examining the contents of the image object comprises determining dimensions of the image. (24) The method according to (23), wherein the adapting step depends on determining a compression ratio of the image object. (25) The type of the image object is GIF
Wherein the adapting step comprises combining the compression ratio with "gif
(24) The method according to (24), which relies on a comparison of a predetermined policy threshold value called "_threshold". (26) The method according to (14), comprising predicting at least one parameter of the transcoded form of the object. (27) The method according to (26), wherein the transcoding format is the same as the original format of the object (28) At least one of the parameters is the size of the transcoding format. (26) The method of (26), wherein at least one of the parameters comprises a time spent transcoding the object.
The method according to (26). (30) A method for predicting a parameter of a transcoding format of an object, wherein the object has an initial size and a size, and the object is received from a server in response to a request from a client for the object. Calculating the bpp ratio of the object; and collecting a set of statistics for a plurality of previously transcoded objects.
Estimating the parameter using the set of statistics and the bpp ratio. (31) The method of (30), wherein at least one of the parameters is a size and the set of statistics includes a size of statistics of a plurality of previously transcoded objects. (32) the object is an image type;
(30) wherein the set of statistics includes image quality;
The described method. (33) The method of (32), wherein the plurality of previously transcoded objects are selected from a predetermined set of benchmarks of an image. (34) The method according to (31), wherein said predicting comprises dynamically updating said set of statistics using statistics of a current transcoded object. (35) The (30) according to (30), wherein at least one of the parameters is a period of forming a transcoded form of the object, and the set of statistics includes a period of forming a plurality of previously transcoded objects. The described method. (36) A transcoding proxy system for facilitating browsing between a plurality of client devices and a plurality of servers connected via a communication network, wherein the transcoding proxy system includes one of the client devices and one of the servers. An HTTP proxy engine for receiving a request for an object stored in an object, an object transcoder using a set of parameters for the transcoding to form a transcoded form of said object, A dynamic policy module to determine the set of parameters; an image size and delay predictor module to collect characteristics of the object; and a user selection to collect a quality selection specified by one user of the client device. Module and bandwidth to estimate effective network bandwidth The dynamic policy module uses inputs received from the image size and delay estimator module, the user selection module, and the bandwidth estimation module to improve user satisfaction. And dynamically adjusting the parameters for transcoding, wherein the transcoding proxy system provides the user with feedback regarding the level of transcoding to be performed. (37) the user selection module comprises: collecting characteristics of one of the client devices, such as display size, resolution, and CPU speed; and providing the characteristics to the dynamic policy module. (36) The system according to (36). (38) The bandwidth estimating module is configured to store one of the servers
Collecting a trace of a previously established network connection between the proxy and one of the client devices; and collecting a trace of a previously established network connection between the proxy and one of the client devices.
Estimating the download time of the object by performing a statistical analysis on the collected traces. (39) The statistical analysis used to estimate the bandwidth between one of the servers and the proxy is determined from the collected traces, the median download time of previously fetched objects, the average Or (3) executed based on the calculation of the statistical index such as mode.
8) The system according to the above. (40) The statistical analysis used to estimate the bandwidth between the proxy and one of the client devices comprises:
The system of claim 38, wherein the system is performed based on a calculation of a total bandwidth of all active connections between the proxy and the client device. (41) On one display device of the client device,
The system of claim 36, further comprising displaying a slide bar for collecting user-specified selections. (42) The system of (36), wherein one user of the client device can specify a trade-off between download time and data quality by using a graphical user interface having a slide bar. (43) One user of the client device can specify a trade-off between download time and image quality by using a graphical user interface having a slide bar, and can output color or gray scale to a desired output format. The system according to (41), further comprising a specific switch for selecting as a. (44) The system automatically reduces the data quality (and thus the data download size) by using a graphical user interface with a slide bar by one user of the client device, You can specify a request to maintain a target response time to compensate for dynamic changes in bandwidth to
The system according to (41). (45) The system according to (41), wherein said slide bar of said graphical user interface is also used as an output interface to indicate to a user an optimal selection of said transcoding parameters. (46) In a transcoding proxy, a product comprising a computer usable medium having computer readable program code means for instructing a dynamic adaptation of a transcoding format of an object, said computer readable program comprising: Code means for instructing a computer to receive an object associated with a user from a server; means for instructing the computer to determine parameters of the object; and retrieving a user selection; Means for instructing the computer; means for instructing the computer to collect current network characteristics; means for instructing the computer to obtain a transcoding policy threshold; and the object parameter. , The user selection, previous Means for instructing the computer to make a policy decision based on network characteristics and the policy threshold; means for instructing the computer to form a transcoded object; An article of manufacture comprising: means for instructing the computer to provide a user with feedback on the level of transcoding to be performed; and means for instructing the computer to send transcoded objects to the user. (47) A computer usable medium having computer readable program code means for directing a transcoding proxy to facilitate browsing between a plurality of client devices and a plurality of servers connected via a communication network. Means for instructing a computer to receive, from one of said client devices, a request for an object stored on one of said servers, the computer readable program code means comprising: Means for instructing the computer to forward a request for the object to one of the servers; means for instructing the computer to receive the object from one of the servers; A choice specified by one user Means for instructing the computer to examine the contents of the object; means for instructing the computer to examine the contents of the object; means for instructing the computer to examine communication network characteristics; Means for instructing the computer to select a set of encoding parameters; means for instructing the computer to form a transcoding form of the object; and Means for instructing the computer to transmit to the computer. (48) the computer readable program code means provides the user with feedback on a level of transcoding performed on the object to form the transcoding form, The product of (47), further comprising means for indicating. (49) The computer readable program code means determines a size of the object,
The product according to (47), comprising: means for instructing the computer; and means for instructing the computer to calculate a compression ratio of the object. (50) The computer readable program code means instructs the computer to start forming the transcoded form before completing the step of receiving the object from one of the servers. (47) The method according to the above (47), comprising: (51) in response to a request from a client for an object available from a server, to form a transcoded form of the object received from said server;
A computer program product comprising computer usable media having computer readable program code means for directing a proxy, wherein the computer program code means transcodes the object for the client. Means for instructing a computer to dynamically adapt the parameters of the object, means for instructing the computer to form a transcoding form of the object, and transmitting the transcoding form to the client. As
Means for directing the computer. (52) The (51) statement, wherein the computer program code means includes means for instructing the computer to collect current network characteristics between the server and the proxy and between the proxy and the client. Computer program products. (53) The computer program code of (52), wherein the computer program code means includes means for instructing the computer to adapt parameters for transcoding based on the estimated bandwidth and user selection. Computer program product. (54) A machine-readable program storage device that implements a program of machine-executable instructions for performing a method of predicting a transcoded parameter of an object, the object having an initial size and dimensions. And wherein the object is received from a server in response to a request from a client for the object, wherein the method calculates a bpp ratio of the object; and a plurality of previously transcoded objects. Gathering a set of statistics, and using the set of statistics and the bpp ratio to predict the parameter.
Program storage. (55) The program storage device according to (54), wherein the step of predicting includes updating the set of statistics using statistics of a current transcoded object.

[Brief description of the drawings]

FIG. 1 illustrates a transcoding proxy situation with different links and different client devices.

FIG. 2 is a block diagram of a transcoding proxy used to transform objects based on user-specified selections and static policies.

FIG. 3 is a block diagram of a transcoding proxy modified to include an image size estimator, a bandwidth estimator, a dynamic policy module, and a user feedback generator, in accordance with the present invention.

FIG. 4 is a block diagram of an HTTP proxy having a caching module and a transcoding module according to the present invention.

FIG. 5 is a flow diagram of a transcoding dynamic policy module according to the present invention.

FIG. 6 uses a transcoding proxy according to the invention;
FIG. 4 illustrates a web request-response cycle.

FIG. 7 illustrates a situation where transcoding is useful according to the invention.

FIG. 8 is a flow diagram of a policy function according to the present invention.

FIG. 9 is a block diagram of an image size prediction module according to the present invention.

FIG. 10 is a block diagram of a bandwidth prediction module according to the present invention.

FIG. 11 illustrates an input / feedback user interface according to the present invention.

FIG. 12 is a timing diagram of stream-based transcoding according to the present invention.

[Explanation of symbols]

100 Transcoding Proxy Status 130, 131, 132, 133, 134, 230 Client 160, 161, 162, 163, 164 Link 190 Transcoding Proxy 210 Web Server 220 HTTP Proxy Engine 222 HTTP Request 226 Response Data 240 Exchange Encoding Module 250 Static Policy Module 260 User-Specified Selection 265 Path 370 Dynamic Policy Module 375 Delay Predictor 380 Bandwidth Estimator 390 User Feedback Provider 400 Transcoding HTTP Proxy System 410 Multi-Resolution Cache 420 Data Path 565, 800 Policy function 620 Original image 630 Output image 650 Delay D _x (S) 670 Size S 680 Size S _x (S) 1010 Trace monitor 1020 Statistical analyzer

Continued on the front page (72) Inventor Pravin Baghat United States 10583, Scarsdale, NY, No. 6, Thienne, Morrow Avenue 40 (72) Inventor Richard Yew-Wayne Han United States 10023, New York, NY, Number 3F, Seventh Fifth Street, West 34 (72) Inventor Richard Orville Lemere United States 10598, Yorktown Heights, NY, California Road 138 (72) Inventor Todd William Mumart United States 10541 Dr. Drive, Mahopak, NY, 18 (72) James Lubas, Inventor 10598, USA, Wildwood Coat 791, Yorktown Heights, NY

Claims (55)

[Claims] 1. A method for a transcoding proxy that facilitates browsing between a plurality of client devices and a plurality of servers connected via a communication network, the method comprising: Receiving a request for an object stored on one of the servers; forwarding the request for the object to one of the servers; receiving the object from one of the servers; the client device Examining a selection specified by one of the users: examining the contents of the object; examining communication network characteristics; selecting a set of transcoding parameters; exchanging the object. Forming an encoding format; The method and transmitting the reduction format to one of said client device. 2. The method according to claim 1, wherein the network characteristics include a bandwidth, and the step of examining the network characteristics comprises determining a network bandwidth between one of the servers and the proxy and between the proxy and one of the client devices. The method of claim 1, comprising estimating. 3. The network characteristic includes a delay, and the step of examining the network characteristic estimates a delay between one of the servers and the proxy, and a delay between the proxy and one of the client devices. The method of claim 1, comprising a step. 4. The method of claim 1, comprising providing feedback to a user regarding the level of transcoding performed on the object to form the transcoding format. 5. The method of claim 1, wherein the step of examining includes determining a size of the object. 6. The method of claim 1, wherein the object is an image type forming an image object, the method comprising: determining a size of the image object; and calculating a compression ratio of the image object. The method of claim 1. 7. The method of claim 6, wherein the dimensions of the image object are determined by the area of the image in square pixels, and the compression ratio is determined by the bpp ratio of the image object. 8. The method of claim 1, wherein said step of forming a transcoding form uses dynamic adaptation. 9. The method of claim 1, wherein the step of forming the transcoded form is started before the step of receiving the object from one of the servers is completed. 10. The method of claim 9, wherein the type of the received object is a JPEG type forming a JPEG object. 11. The step of forming a transcoded form includes performing JPEG-JPEG image transcoding, and the step of transmitting the transcoded form comprises the step of performing a JPEG-JPEG image transform before the object is completed. The method of claim 10, wherein writing of at least one MCU of the encoded output image data is initiated. 12. The step of sending the transcoded form starts after processing an initial portion of the received object and before the step of receiving the image object from one of the servers is completed. The method of claim 1. 13. The method of claim 1, wherein the step of sending the transcoded form is started before the step of forming the transcoded form of the object is completed. 14. A method for a proxy to form a transcoded form of an object received from a server in response to a request from a client for an object available from the server, the method comprising: A method comprising: dynamically adapting parameters for transcoding an object; forming a transcoding form of the object; and transmitting the transcoding form to the client. . 15. The method of claim 14, wherein adapting the parameter comprises determining at least one characteristic of the object. 16. The method of claim 15, wherein one of the characteristics is an object header that provides information about the size and type of the object. 17. The size of the object is set to "size_thre
17. The method of claim 16 including comparing with a threshold parameter called "shold". 18. The method of claim 14, wherein adapting the parameters comprises gathering current network characteristics between the server and the proxy and between the proxy and the client. 19. The method of claim 18, wherein one of the characteristics is network bandwidth, and wherein the adapting comprises estimating network bandwidth between the server and the proxy and between the proxy and the client. 1
8. The method according to 8. 20. The method of claim 19, wherein said transcoding format depends on said estimated bandwidth. 21. The method of claim 14, wherein said adapting comprises retrieving a user's selection, and wherein said transcoding format is dependent on said selection. 22. The method of claim 14, wherein said adapting step comprises examining the contents of said object. 23. The method of claim 22, wherein said object is an image type forming an image object, and wherein examining the contents of the image object comprises determining dimensions of the image. 24. The method of claim 2, wherein the step of adapting relies on a determination of a compression ratio of the image object.
3. The method according to 3. 25. The method of claim 24, wherein the type of the image object is GIF, and wherein the adapting step relies on a comparison between the compression ratio and a predetermined policy threshold called "gif_threshold". . 26. The method of claim 14, comprising predicting at least one parameter of the transcoded form of the object. 27. The method of claim 26, wherein said transcoding format is the same as the original format of said object. 28. The method of claim 26, wherein at least one of the parameters comprises a size of the transcoding format. 29. The method of claim 26, wherein at least one of the parameters comprises a time spent transcoding the object. 30. A method for predicting a transcoded parameter of an object, the object having an initial size and dimensions, wherein the object is received from a server in response to a request from a client for the object. Calculating a bpp ratio for the object; collecting a set of statistics for a plurality of previously transcoded objects; using the set of statistics and the bpp ratio to calculate the parameter. Predicting. 31. The method of claim 30, wherein at least one of the parameters is a size, and the set of statistics includes a size of statistics of a plurality of previously transcoded objects.
The described method. 32. The method of claim 30, wherein said object is of image type and said set of statistics includes image quality. 33. The method of claim 32, wherein the plurality of previously transcoded objects are selected from a predetermined set of benchmarks of an image. 34. The method of claim 31, wherein the step of predicting comprises dynamically updating the set of statistics with statistics of a current transcoded object. 35. The method of claim 35, wherein at least one of the parameters is a period of time forming a transcoded form of the object, and the set of statistics includes a period of time forming a plurality of previously transcoded objects. 30. The method of claim 30. 36. A transcoding proxy system for facilitating browsing between a plurality of client devices and a plurality of servers connected via a communication network, the transcoding proxy system comprising: HTT receiving requests for objects stored in one
A P-proxy engine, an object transcoder forming a transcoding format of the object using the set of parameters for transcoding, and a dynamic determining the set of parameters for transcoding. A policy module; an image size and delay predictor module for collecting characteristics of the object; a user selection module for collecting quality selections specified by one user of the client device; and estimating an effective network bandwidth. A bandwidth estimation module, the dynamic policy module receiving input from the image size and delay estimator module, the user selection module, and the bandwidth estimation module to improve user satisfaction. Using the parameters for transcoding Dynamically adjusted, the exchange coded proxy system provides feedback regarding the level of exchange encoding performed by the user, the system. 37. The user selection module comprising: collecting characteristics such as display size, resolution, and CPU speed of one of the client devices; and providing the characteristics to the dynamic policy module. 37. The system of claim 36. 38. The bandwidth estimating module comprising: collecting traces of previously established network connections between one of the servers and the proxy; between the proxy and one of the client devices;
37. The system of claim 36, comprising: collecting a trace of a previously established network connection; and performing a statistical analysis on the collected trace to estimate the download time of the object. . 39. A statistical analysis used to estimate bandwidth between one of said servers and said proxy, wherein said statistical analysis is determined from said collected traces, the median download time of previously fetched objects. 39. The system of claim 38, wherein the system is performed based on a calculation of a statistical indicator, such as, an average or a mode. 40. The statistical analysis used to estimate the bandwidth between the proxy and one of the client devices comprises the step of calculating the total bandwidth of all active connections between the proxy and the client device. 39. The system of claim 38, wherein the system is performed based on a calculation. 41. The system of claim 36, further comprising the step of displaying a slide bar for collecting user-specified selections on a display of one of the client devices. 42. A user of one of the client devices can specify a trade-off between download time and data quality by using a graphical user interface having a slide bar.
6. The system according to 6. 43. A user of one of said client devices can specify a trade-off between download time and image quality by using a graphical user interface having a slide bar, and can set a desired color or gray scale. 42. The system of claim 41, including a specific switch for selecting as an output format. 44. A system in which one user of said client device automatically reduces data quality (and thus data download size) by using a graphical user interface having a slide bar; 42. The system of claim 41, wherein a request to maintain a target response time can be specified to compensate for dynamic changes in bandwidth to the client. 45. The system of claim 41, wherein said slide bar of said graphical user interface is also used as an output interface to indicate to a user an optimal selection of said transcoding parameters. 46. A transcoding proxy, comprising a computer readable medium having computer readable program code means for directing a dynamic adaptation of a transcoding format of an object, said computer readable medium comprising said computer readable medium. Program code means for instructing a computer to receive an object associated with a user from a server; means for instructing the computer to determine parameters of the object; and retrieving a user selection. Means for instructing the computer; means for instructing the computer to collect current network characteristics; means for instructing the computer to obtain a transcoding policy threshold; and the object Parameters, the user Means for instructing the computer to make a policy decision based on the selection, the network characteristics, and the policy threshold; and means for instructing the computer to form a transcoded object. Means for instructing the computer to provide a user with feedback of the level of transcoding performed on the object; and means for instructing the computer to send the transcoded object to the user. , Products. 47. Instruct a transcoding proxy to facilitate browsing between a plurality of client devices and a plurality of servers connected via a communication network;
An article of manufacture comprising a computer usable medium having computer readable program code means, the computer readable program code means comprising: a request from one of the client devices for an object stored on one of the servers. Means for instructing a computer to receive the object; means for instructing the computer to forward a request for the object to one of the servers; and receiving the object from one of the servers. Means for instructing the computer; means for instructing the computer to examine a selection specified by one user of the client device; and instructing the computer to investigate the contents of the object. Means and communication network To investigate the sexual, and means for instructing the computer to select a set of replacement coding parameters, and means for instructing the computer, so as to form an exchange encoding format of the object,
A product comprising: means for instructing the computer; and means for instructing the computer to transmit the transcoded format to one of the client devices. 48. The computer readable program code means for providing a user with feedback as to the level of transcoding performed on the object to form the transcoding format. 5. The method according to claim 4, further comprising means for instructing the computer.
7. The product according to 7. 49. The computer readable program code means for instructing the computer to determine a size of the object, and for instructing the computer to calculate a compression ratio of the object. 48. The product of claim 47, comprising: 50. The computer-readable medium according to claim 50, wherein the computer-readable program code means initiates the step of forming the transcoded form before the step of receiving the object from one of the servers is completed. 50. The method of claim 47, further comprising means for indicating 51. Computer readable program code means for instructing a proxy to form a transcoded form of an object received from a server in response to a request from a client for an object available from the server. A computer program product comprising a computer usable medium, wherein the computer program code means dynamically adapts parameters for transcoding the object for the client. Means for instructing a computer; and forming a transcoded form of the object,
A computer program product comprising: means for instructing the computer; and means for instructing the computer to transmit the transcoded format to the client. 52. The computer program code means includes means for instructing the computer to gather current network characteristics between the server and the proxy and between the proxy and the client. Computer program product as described. 53. The computer program code means includes means for instructing the computer to adapt parameters for transcoding based on estimated bandwidth and user selection. Computer program products. 54. A machine-readable program storage device for implementing a program of machine-executable instructions for performing a method of predicting a transcoded parameter of an object, wherein the object has an initial size and Having dimensions, wherein the object is received from a server in response to a request from a client for the object, the method comprising: calculating a bpp ratio of the object; A program storage device, comprising: collecting a set of statistics for the objects that have been generated; and using the set of statistics and the bpp ratio to predict the parameters. 55. The program storage device according to claim 54, wherein the step of predicting includes updating the set of statistics using statistics of a current transcoded object.