compression

问题 I am trying to install the brotli package in R. As usual, I run: install.packages("brotli") However, for some reason, the compilation seems to not be completing. I have tried this now on two different systems (one on my Mac, the other on an EC2 instance). Here are the errors: wrapper.c:94:14: error: unknown type name 'R_CallMethodDef' static const R_CallMethodDef CallEntries[] = { ^ wrapper.c:95:28: error: use of undeclared identifier 'DL_FUNC' {"R_brotli_compress", (DL_FUNC) &R_brotli

问题 I am trying to build a fast 8-bit greyscale PNG encoder. Unfortunately I must be misunderstanding part of the spec. Smaller image sizes seem to work, but the larger ones will only open in some image viewers. This image (with multiple DEFLATE Blocks) gives a "Decompression error in IDAT" error in my image viewer but opens fine in my browser: This image has just one DEFLATE block but also gives an error: Below I will outline what I put in my IDAT chunk in case you can easily spot any mistakes

问题 What is the best compression algorithm with the following features: should take less time to decompress (can take reasonably more time compress) should be able to compress sorted data (approx list of 3,000,000 strings/integers ...) Please suggest along with metrics: compression ratio, algorithmic complexity for compression and decompression (if possible)? 回答1: Entire site devoted to compression benchmarking here 回答2: Well if you just want speed, then standard ZIP compression is just fine and

问题 I'm resizing jpegs by using the Graphics.DrawImage method (see code fragment below). Can anyone confirm that this will not affect the compression of the new image? I have seen this thread, but I am talking specifically about compression of jpegs. private byte[] getResizedImage(String url, int newWidth) { Bitmap bmpOut = null; System.IO.MemoryStream outStream = new System.IO.MemoryStream(); //input image is disposable using (Bitmap inputImage = LoadImageFromURL(url)) { ImageFormat format =

问题 I want to use gzip with GWT Please suggest how do i compress my GWT nocache.js,cache.html and gwt.rpc files using gzip Please help me Thanks 回答1: Generally, gzip is enabled on the server that your files are being hosted on, and you can do it for all files on your site rather than just those 3. This site helps you test whether gzip is enabled on your site: http://www.whatsmyip.org/http_compression/ Here's how to turn gzip on with the Apache web server: http://httpd.apache.org/docs/2.0/mod/mod

问题 Is it possible to compress data (programmatically) in SQL Server using zlib compression? It's just one column in a specific table that needs compressing. I'm not a SQL Server person myself - I've tried to find if there's anything available but not had much joy. Thanks 来源： https://stackoverflow.com/questions/28324017/is-it-possible-to-compress-data-in-sql-server-using-zlib

问题 I am writing ZLIB like API for an embedded hardware compressor which uses deflate algorithm for compression of given input stream. Before going further i would like to explain data compression ratio. Data compression ratio is defined as the ratio between the uncompressed size and compressed size. Compression ratio is usually greater than one. which mean compressed data is usually smaller than uncompressed data, which is whole point to do compression. but this is not always the case. for

问题 I'm trying to send a bitmap screenshot over network, so I need to compress it before sending it. Is there a library or method for doing this? 回答1: When you save an Image to a stream, you have to select a format. Almost all bitmap formats (bmp, gif, jpg, png) use 1 or more forms of compression. So just select an appropriate format, and make make sure that sender and receiver agree on it. 回答2: Try the System.IO.DeflateStream class. 回答3: If you are looking for something to compress the image in

问题 I am using QNetworkManager to fetch files from a server, however what I cannot figure out is if the files are compressed during the transfer with the standard gzip compression and if not how to get them to download compressed. How would I go about checking? 回答1: I just ran a quick test by adding: request.setRawHeader("Accept-Encoding", "gzip,deflate"); to the QNetworkRequest and the data returns what look compressed (because its ~20% smaller and unusable). It appears that the QNetworkManager

问题 I have a function that keeps track of events that happen through out the script. In an effort to use my resources effectively, I decided to compress the data that it generates. However, I keep getting this error: Unknown error type: [2] gzuncompress() [function.gzuncompress]: data error Here's the function: function eventlog($type, $message){ // Types: account,run,queue,system // Set up file name/location $eventfile = '/myprivatedirectory/'.date('Ymd').$type.'.log'; if(file_exists($eventfile)