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  • UIImageJPEGRepresentation - memory release issue

    - by FredM
    On a iPhone app, I need to send a jpg by mail with a maximum size of 300Ko (I don't no the maximum size mail.app can have, but it's another problem). To do that, I'm trying to decrease quality until obtain an image under 300Ko. In order to obtain the good value of the quality (compressionLevel) who give me a jpg under 300Ko, I have made the following loop. It's working, but each time time the loop is executed, the memory increase of the size of the original size of my jpg (700Ko) despite the "[tmpImage release];". float compressionLevel = 1.0f; int size = 300001; while (size 300000) { UIImage *tmpImage =[[UIImage alloc] initWithContentsOfFile:[self fullDocumentsPathForTheFile:@"countOpix_imageToAnalyse.jpg"]]; size = [UIImageJPEGRepresentation(tmpImage, compressionLevel) length]; [tmpImage release]; //In the following line, the 0.001f decrement is choose just in order test the increase of the memory //compressionLevel = compressionLevel - 0.001f; NSLog(@"Compression: %f",compressionLevel); } Any ideas about how can i get it off, or why it happens? thanks

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  • How to best transfer large payloads of data using wsHttp with WCF with message security

    - by jpierson
    I have a case where I need to transfer large amounts of serialized object graphs (via NetDataContractSerializer) using WCF using wsHttp. I'm using message security and would like to continue to do so. Using this setup I would like to transfer serialized object graph which can sometimes approach around 300MB or so but when I try to do so I've started seeing a exception of type System.InsufficientMemoryException appear. After a little research it appears that by default in WCF that a result to a service call is contained within a single message by default which contains the serialized data and this data is buffered by default on the server until the whole message is completely written. Thus the memory exception is being caused by the fact that the server is running out of memory resources that it is allowed to allocate because that buffer is full. The two main recommendations that I've come across are to use streaming or chunking to solve this problem however it is not clear to me what that involves and whether either solution is possible with my current setup (wsHttp/NetDataContractSerializer/Message Security). So far I understand that to use streaming message security would not work because message encryption and decryption need to work on the whole set of data and not a partial message. Chunking however sounds like it might be possible however it is not clear to me how it would be done with the other constraints that I've listed. If anybody could offer some guidance on what solutions are available and how to go about implementing it I would greatly appreciate it. Related resources: Chunking Channel How to: Enable Streaming Large attachments over WCF Custom Message Encoder Another spotting of InsufficientMemoryException I'm also interested in any type of compression that could be done on this data but it looks like I would probably be best off doing this at the transport level once I can transition into .NET 4.0 so that the client will automatically support the gzip headers if I understand this properly.

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  • htaccess redirect http to https on a magento site

    - by joesalvator
    I have a magento site and i need to have it redirect to https, i have the cert installed but i am not sure how to mod the htaccess file? here is a copy of the root htaccess file thanks # uncomment these lines for CGI mode make sure to specify the correct cgi php binary file name it might be /cgi-bin/php-cgi Action php5-cgi /cgi-bin/php5-cgi AddHandler php5-cgi .php # GoDaddy specific options Options -MultiViews you might also need to add this line to php.ini cgi.fix_pathinfo = 1 if it still doesn't work, rename php.ini to php5.ini # this line is specific for 1and1 hosting #AddType x-mapp-php5 .php #AddHandler x-mapp-php5 .php # default index file DirectoryIndex index.php # adjust memory limit php_value memory_limit 64M php_value memory_limit 128M php_value max_execution_time 18000 # disable magic quotes for php request vars php_flag magic_quotes_gpc off # disable automatic session start before autoload was initialized php_flag session.auto_start off # enable resulting html compression #php_flag zlib.output_compression on # disable user agent verification to not break multiple image upload php_flag suhosin.session.cryptua off # turn off compatibility with PHP4 when dealing with objects php_flag zend.ze1_compatibility_mode Off # disable POST processing to not break multiple image upload SecFilterEngine Off SecFilterScanPOST Off # # Insert filter on all content ###SetOutputFilter DEFLATE # Insert filter on selected content types only #AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript # Netscape 4.x has some problems... #BrowserMatch ^Mozilla/4 gzip-only-text/html # Netscape 4.06-4.08 have some more problems #BrowserMatch ^Mozilla/4\.0[678] no-gzip # MSIE masquerades as Netscape, but it is fine #BrowserMatch \bMSIE !no-gzip !gzip-only-text/html # Don't compress images #SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip dont-vary # Make sure proxies don't deliver the wrong content #Header append Vary User-Agent env=!dont-vary # make HTTPS env vars available for CGI mode SSLOptions StdEnvVars # enable rewrites Options +FollowSymLinks RewriteEngine on # you can put here your magento root folder path relative to web root #RewriteBase /magento/ # workaround for HTTP authorization in CGI environment RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}] # always send 404 on missing files in these folders RewriteCond %{REQUEST_URI} !^/(media|skin|js)/ # never rewrite for existing files, directories and links RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-l # rewrite everything else to index.php RewriteRule .* index.php [L] # Prevent character encoding issues from server overrides If you still have problems, use the second line instead AddDefaultCharset Off #AddDefaultCharset UTF-8 # s ExpiresDefault "access plus 1 year" # By default allow all access Order allow,deny Allow from all

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  • Working with a large data object between ruby processes

    - by Gdeglin
    I have a Ruby hash that reaches approximately 10 megabytes if written to a file using Marshal.dump. After gzip compression it is approximately 500 kilobytes. Iterating through and altering this hash is very fast in ruby (fractions of a millisecond). Even copying it is extremely fast. The problem is that I need to share the data in this hash between Ruby on Rails processes. In order to do this using the Rails cache (file_store or memcached) I need to Marshal.dump the file first, however this incurs a 1000 millisecond delay when serializing the file and a 400 millisecond delay when serializing it. Ideally I would want to be able to save and load this hash from each process in under 100 milliseconds. One idea is to spawn a new Ruby process to hold this hash that provides an API to the other processes to modify or process the data within it, but I want to avoid doing this unless I'm certain that there are no other ways to share this object quickly. Is there a way I can more directly share this hash between processes without needing to serialize or deserialize it? Here is the code I'm using to generate a hash similar to the one I'm working with: @a = [] 0.upto(500) do |r| @a[r] = [] 0.upto(10_000) do |c| if rand(10) == 0 @a[r][c] = 1 # 10% chance of being 1 else @a[r][c] = 0 end end end @c = Marshal.dump(@a) # 1000 milliseconds Marshal.load(@c) # 400 milliseconds Update: Since my original question did not receive many responses, I'm assuming there's no solution as easy as I would have hoped. Presently I'm considering two options: Create a Sinatra application to store this hash with an API to modify/access it. Create a C application to do the same as #1, but a lot faster. The scope of my problem has increased such that the hash may be larger than my original example. So #2 may be necessary. But I have no idea where to start in terms of writing a C application that exposes an appropriate API. A good walkthrough through how best to implement #1 or #2 may receive best answer credit.

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  • Web scraping etiquette

    - by Ash
    I'm considering writing a simple web scraping application to extract information from a website that does not seem to specifically prohibit this. I've checked for other alternatives (eg RSS, web service) to get this information, but there are none available at this stage. Despite this I've also developed/maintained a few websites myself and so I realize that if web scraping is done naively/greedily it can slow things down for other users and generally become a nuisance. So, what etiquette is involved in terms of: Number of requests per second/minute/hour. HTTP User Agent content. HTTP Referer content. HTTP Cache settings. Buffer size for larger files/resources. Legalities and licensing issues. Good tools or design approaches to use. Robots.txt, is this relevant for web scraping or just crawlers/spiders? Compression such as GZip in requests. Update Found this relevant question on Meta: Etiquette of Screen Scaping StackOverflow. Jeff Atwood's answer has some helpful recommendations. Other related StackOverflow questions: Options for html scraping Legalities of screen scraping

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  • Creating a shim Stream

    - by spender
    A decompression API that I am using has the following API: Decode(Stream inStream,Stream outStream) I'd like to create a wrapper around this API, such that I can create my own Stream class which offers up the decoded data. Stream decodedStream=new BlaDecodeStream(inStream); So that I can than use this stream as a parameter to the XmlReader constructor in the same way one might use the System.IO.Compression.GZipStream. As far as I can tell, the only other option is set outStream stream to a MemoryStream or to a FileStream and go in two hops. The files I am dealing with are enormous, so neither of these options are particularly attractive. Before I go reinventing the wheel, is there any prior art that I might be able to draw from, or something in the BCL I might have missed? The CircularStream implementation here would go some of the way to helping, but I'm really looking for something similar that would block (as opposed to over/underrun) when the Stream's internal buffer is 'empty' when reading from it and block when the internal buffer is full when writing to it. In this way it could serve as parameter outStream and simultaneously (i.e. from another thread) could be read from by the XmlReader.

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  • What does this svn2git error mean?

    - by Hisham
    I am trying to import my repository from svn to git using svn2git, but it seems like it's failing when it hits a branch. What's the problem? Found possible branch point: https://s.aaa.com/repo/trunk/project => https://s.aaa.com/repo/branches/project-beta1.0, 128 Use of uninitialized value in substitution (s///) at /opt/local/libexec/git-core/git-svn line 1728. Use of uninitialized value in concatenation (.) or string at /opt/local/libexec/git-core/git-svn line 1728. refs/remotes/trunk: 'https://s.aaa.com/repo' not found in '' Running command: git branch -l --no-color * master Running command: git branch -r --no-color trunk Running command: git checkout trunk Note: checking out 'trunk'. You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout. If you want to create a new branch to retain commits you create, you may do so (now or later) by using -b with the checkout command again. Example: git checkout -b new_branch_name HEAD is now at f4e6268... Changing svn repository in cap files Running command: git branch -D master Deleted branch master (was f4e6268). Running command: git checkout -f -b master Switched to a new branch 'master' Running command: git gc Counting objects: 450, done. Delta compression using up to 2 threads. Compressing objects: 100% (368/368), done. Writing objects: 100% (450/450), done. Total 450 (delta 63), reused 450 (delta 63)

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  • Is a VCS appropriate for usage by a designer?

    - by iconiK
    I know that a VCS is absolutely critical for a developer to increase productivity and protect the code, no doubts about it. But what about a designer, using say, Photoshop (though it's not specific to any tools, just to make my point clearer). VCSs uses delta compression to store different versions of files. This works very well for code, but for images, that's a problem. Raster image files are binary formats, though vector image files are text (SVG comes to my mind) and pose to problem. The problem comes with .psd files (and any other image "source" file) - those can get pretty big and since I'm not familiar with the format, I'll consider them as binary files. How would a VCS work in this condition? The repository could be pretty darned big if the VCS server isn't able to diff the files efficiently (or worse, not at all) and over time this can become a really big pain when someone needs to check out the repository (or clone it if using a DVCS). Have any of you used a VCS for this purpose? How well does it work? I'm mostly interested in Mercurial, though this is a general situation that applies to any VCS.

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  • BMP2AVI program in matlab

    - by ariel
    HI I wrote a program that use to work (swear to god) and has stopped from working. this code takes a series of BMPs and convert them into avi file. this is the code: path4avi='C:/FadeOutMask/'; %dont forget the '/' in the end of the path pathOfFrames='C:/FadeOutMask/'; NumberOfFiles=1; NumberOfFrames=10; %1:1:(NumberOfFiles) for i=0:1:(NumberOfFiles-1) FileName=strcat(path4avi,'FadeMaskAsael',int2str(i),'.avi') %the generated file aviobj = avifile(FileName,'compression','None'); aviobj.fps=10; for j=0:1:(NumberOfFrames-1) Frame=strcat(pathOfFrames,'MaskFade',int2str(i*10+j),'.bmp') %not a good name for thedirectory [Fa,map]=imread(Frame); imshow(Fa,map); F=getframe(); aviobj=addframe(aviobj,F) end aviobj=close(aviobj); end And this is the error I get: ??? Error using ==> checkDisplayRange at 22 HIGH must be greater than LOW. Error in ==> imageDisplayValidateParams at 57 common_args.DisplayRange = checkDisplayRange(common_args.DisplayRange,mfilename); Error in ==> imageDisplayParseInputs at 79 common_args = imageDisplayValidateParams(common_args); Error in ==> imshow at 199 [common_args,specific_args] = ... Error in ==> ConverterDosenWorkd at 19 imshow(Fa,map); for some reason I cant put it as code segments. sorry thank you Ariel

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  • How can I transform XML to invalid XML using XSLT?

    - by Damovisa
    I need to transform a valid XML document to the OFX v1.0.2 format. This format is more or less XML, but it's technically invalid and therefore cannot be parsed as XML. I'm having trouble getting my Xml transformation working because the .Net XslCompiledTransform object insists on interpreting the XSL as an XML document (which is fair enough). If I escape the xml-ish tags using &lt; and &gt, they get removed when I download the file. Here's the start of my XSLT: <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:output method="text"></xsl:output> <xsl:param name="currentdate"></xsl:param> <xsl:template match="Transactions"> OFXHEADER:100 DATA:OFXSGML VERSION:102 SECURITY:NONE ENCODING:USASCII CHARSET:1252 COMPRESSION:NONE OLDFILEUID:NONE NEWFILEUID:NONE <OFX> <SIGNONMSGSRSV1> <SONRS> <STATUS> <CODE>0 <SEVERITY>INFO </STATUS> <DTSERVER><xsl:value-of select="$currentdate" /> <LANGUAGE>ENG Any suggestions?

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  • Sharing large objects between ruby processes without a performance hit

    - by Gdeglin
    I have a Ruby hash that reaches approximately 10 megabytes if written to a file using Marshal.dump. After gzip compression it is approximately 500 kilobytes. Iterating through and altering this hash is very fast in ruby (fractions of a millisecond). Even copying it is extremely fast. The problem is that I need to share the data in this hash between Ruby on Rails processes. In order to do this using the Rails cache (file_store or memcached) I need to Marshal.dump the file first, however this incurs a 1000 millisecond delay when serializing the file and a 400 millisecond delay when serializing it. Ideally I would want to be able to save and load this hash from each process in under 100 milliseconds. One idea is to spawn a new Ruby process to hold this hash that provides an API to the other processes to modify or process the data within it, but I want to avoid doing this unless I'm certain that there are no other ways to share this object quickly. Is there a way I can more directly share this hash between processes without needing to serialize or deserialize it? Here is the code I'm using to generate a hash similar to the one I'm working with: @a = [] 0.upto(500) do |r| @a[r] = [] 0.upto(10_000) do |c| if rand(10) == 0 @a[r][c] = 1 # 10% chance of being 1 else @a[r][c] = 0 end end end @c = Marshal.dump(@a) # 1000 milliseconds Marshal.load(@c) # 400 milliseconds

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  • Producing CCITT compressed TIFF from CGImage

    - by Brian Postow
    I have a CGImage (core graphics, C/C++). It's grayscale. Well, originally it was B/W, but the CGImage may be RGB. That shouldn't matter. I want to create a CCITT-Group 4 TIFF. I can create an LZW TIFF (grayscale or color) via creating a destination with the correct dictionary and adding the image in. No problem. However, there doesn't seem to be an equivalent kCGImagePropertyTIFFCompression value to represent CCITT-4. It should be 4, but that produces uncompressed. I have a manual CCITT compression routine, so if I can get the binary (1 bit per pixel) data, I'm set. But I can't seem to get 1 BPP data out of a CGImage. I have code that is supposed to put the CGImage into a CGBitmapContext and then give me the data, but it seems to be giving me all black. I've asked a couple of questions today trying to get at this, but I just figured, lets ask the question I REALLY want answered and see if someone can answer it. There's GOT to be a way to do this. I've got to be missing something dumb. What is it?

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  • Multiple connections in a single SSH SOCKS 5 Proxy

    - by Elie Zedeck
    Hey guys, My fist question here on Stackoverflow: What should I need to do so that the SSH SOCKS 5 Proxy (SSH2) will allow multiple connections? What I have noticed, is that when I load a page in Firefox (already configured to use the SOCKS 5 proxy), it loads everything one by one. It can be perceived by bare eyes, and I also confirm that through the use of Firebug's NET tab, which logs the connections that have been made. I have already configure some of the directives in the about:config page, like pipeline, persistent proxy connections, and a few other things. But I still get this kind of sequential load of resources, which is noticeably very slow. network.http.pipelining;true network.http.pipelining.maxrequests;8 network.http.pipelining.ssl;true network.http.proxy.pipelining;true network.http.max-persistent-connections-per-proxy;100 network.proxy.socks_remote_dns;true My ISP sucks because during the day, it intentionally breaks connections on a random basis. And so, it is impossible to actually accomplish meaningful works without the need of a lot of browser refresh or hitting F5 key. So, that is why I started to find solutions to this. The SSH's dynamic port forwarding is the best solution I find to date, because it has some pretty good compression which saves a lot of useless traffic, and is also secure. The only thing remaining is to get it to have multiple connections running in it. Thanks for all the inputs.

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  • Why am I getting an error on Heroku that suggests I need to migrate my app to Bamboo?

    - by user242065
    When I type: git push heroku master, this is what happens @68-185-86-134:sample_app git push heroku master Counting objects: 110, done. Delta compression using up to 2 threads. Compressing objects: 100% (94/94), done. Writing objects: 100% (110/110), 87.48 KiB, done. Total 110 (delta 19), reused 0 (delta 0) -----> Heroku receiving push -----> Rails app detected ! This version of Rails is only supported on the Bamboo stack ! Please migrate your app to Bamboo and push again. ! See http://docs.heroku.com/bamboo for more information ! Heroku push rejected, incompatible Rails version error: hooks/pre-receive exited with error code 1 To [email protected]:blazing-frost-89.git ! [remote rejected] master -> master (pre-receive hook declined) error: failed to push some refs to '[email protected]:blazing-frost-89.git' My .gems file: rails --version 2.3.8 My .git/config file: [core] repositoryformatversion = 0 filemode = true bare = false logallrefupdates = true ignorecase = true [remote "origin"] url = [email protected]:csmeder/sample_app.git fetch = +refs/heads/*:refs/remotes/origin/* [remote "heroku"] url = [email protected]:blazing-frost-89.git fetch = +refs/heads/*:refs/remotes/heroku/*

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  • How to get the "real" colors when exporting a GDI drawing to bmp

    - by Rodrigo
    Hi guys I'm developing a ASP.Net web handler that returns images making a in-memory System.Windows.Forms.Control and then exports the rendered control as a bitmap compressed to PNG, using the method DrawToBitmap(). The classes are fully working by now, except for a problem with the color assignment. By example, this is a Gauge generated by the web handler. The colors assigned to the inner parts of the gauge are red (#FF0000), yellow (#FFFF00) and green (#00FF00) but I only get a dully version of each color (#CB100F for red, #CCB70D for yellow and #04D50D for green). The background is a bmp file containing the color gradient. The color loss happens whether the background is a gradient as the sample, a black canvas, a white canvas, a transparent canvas, even when there is not a background set. With black background With transparent background With a white background Without a background set With pixel format in Format32bppArgb I've tried multiple bitmap color deeps, output formats, compression level, etc. but none of them seems to work. Any ideas? This is a excerpt of the source code: Bitmap bmp = new Bitmap(w, h, System.Drawing.Imaging.PixelFormat.Format32bppPArgb); Image bgimage = (Image) HttpContext.GetGlobalResourceObject("GraphicResources", "GaugeBackgroundImage"); Canvas control_canvas = new Canvas(); .... //the routine that makes the gauge .... control_canvas.DrawToBitmap(bmp, new Rectangle(0, 0, w, h));

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  • moving audio over a local network using GStreamer

    - by James Turner
    I need to move realtime audio between two Linux machines, which are both running custom software (of mine) which builds on top of Gstreamer. (The software already has other communication between the machines, over a separate TCP-based protocol - I mention this in case having reliable out-of-band data makes a difference to the solution). The audio input will be a microphone / line-in on the sending machine, and normal audio output as the sink on the destination; alsasrc and alsasink are the most likely, though for testing I have been using the audiotestsrc instead of a real microphone. GStreamer offers a multitude of ways to move data round over networks - RTP, RTSP, GDP payloading, UDP and TCP servers, clients and sockets, and so on. There's also many examples on the web of streaming both audio and video - but none of them seem to work for me, in practice; either the destination pipeline fails to negotiate caps, or I hear a single packet and then the pipeline stalls, or the destination pipeline bails out immediately with no data available. In all cases, I'm testing on the command-line just gst-launch. No compression of the audio data is required - raw audio, or trivial WAV, uLaw or aLaw encoding is fine; what's more important is low-ish latency.

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  • Fastest PNG decoder for .NET

    - by sboisse
    Our web server needs to process many compositions of large images together before sending the results to web clients. This process is performance critical because the server can receive several thousands of requests per hour. Right now our solution loads PNG files (around 1MB each) from the HD and sends them to the video card so the composition is done on the GPU. We first tried loading our images using the PNG decoder exposed by the XNA API. We saw the performance was not too good. To understand if the problem was loading from the HD or the decoding of the PNG, we modified that by loading the file in a memory stream, and then sending that memory stream to the .NET PNG decoder. The difference of performance using XNA or using System.Windows.Media.Imaging.PngBitmapDecoder class is not significant. We roughly get the same levels of performance. Our benchmarks show the following performance results: Load images from disk: 37.76ms 1% Decode PNGs: 2816.97ms 77% Load images on Video Hardware: 196.67ms 5% Composition: 87.80ms 2% Get composition result from Video Hardware: 166.21ms 5% Encode to PNG: 318.13ms 9% Store to disk: 3.96ms 0% Clean up: 53.00ms 1% Total: 3680.50ms 100% From these results we see that the slowest parts are when decoding the PNG. So we are wondering if there wouldn't be a PNG decoder we could use that would allow us to reduce the PNG decoding time. We also considered keeping the images uncompressed on the hard disk, but then each image would be 10MB in size instead of 1MB and since there are several tens of thousands of these images stored on the hard disk, it is not possible to store them all without compression.

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  • How to read/write high-resolution (24-bit, 8 channel) .wav files in Java?

    - by dB'
    I'm trying to write a Java application that manipulates high resolution .wav files. I'm having trouble importing the audio data, i.e. converting the .wav file into an array of doubles. When I use a standard approach an exception is thrown. AudioFileFormat as = AudioSystem.getAudioFileFormat(new File("orig.wav")); --> javax.sound.sampled.UnsupportedAudioFileException: file is not a supported file type Here's the file format info according to soxi: dB$ soxi orig.wav soxi WARN wav: wave header missing FmtExt chunk Input File : 'orig.wav' Channels : 8 Sample Rate : 96000 Precision : 24-bit Duration : 00:00:03.16 = 303526 samples ~ 237.13 CDDA sectors File Size : 9.71M Bit Rate : 24.6M Sample Encoding: 32-bit Floating Point PCM Can anyone suggest the simplest method for getting this audio into Java? I've tried using a few techniques. As stated above, I've experimented with the Java AudioSystem (on both Mac and Windows). I've also tried using Andrew Greensted's WavFile class, but this also fails (WavFileException: Compression Code 3 not supported). One workaround is to convert the audio to 16 bits using sox (with the -b 16 flag), but this is suboptimal since it increases the noise floor. Incidentally, I've noticed that the file CAN be read by libsndfile. Is my best bet to write a jni wrapper around libsndfile, or can you suggest something quicker? Note that I don't need to play the audio, I just need to analyze it, manipulate it, and then write it out to a new .wav file. * UPDATE * I solved this problem by modifying Andrew Greensted's WavFile class. His original version only read files encoded as integer values ("format code 1"); my files were encoded as floats ("format code 3"), and that's what was causing the problem. I'll post the modified version of Greensted's code when I get a chance. In the meantime, if anyone wants it, send me a message.

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  • Altruistic network connection bandwidth estimation

    - by datenwolf
    Assume two peers Alice and Bob connected over a IP network. Alice and Bob are exchanging packets of lossy compressed data which are generated and to be consumes in real time (think a VoIP or video chat application). The service is designed to cope with as little bandwidth available, but relies on low latencies. Alice and Bob would mark their connection with an apropriate QoS profile. Alice and Bob want use a variable bitrate compression and would like to consume all of the leftover bandwidth available for the connection between them, but would voluntarily reduce the consumed bitrate depending on the state of the network. However they'd like to retain a stable link, i.e. avoid interruptions in their decoded data stream caused by congestion and the delay until the bandwidth got adjusted. However it is perfectly possible for them to loose a few packets. TL;DR: Alice and Bob want to implement a VoIP protocol from scratch, and are curious about bandwidth and congestion control. What papers and resources do you suggest for Alice and Bob to read? Mainly in the area of bandwidth estimation and congestion control.

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  • With Go, how to append unknown number of byte into a vector and get a slice of bytes?

    - by Stephen Hsu
    I'm trying to encode a large number to a list of bytes(uint8 in Go). The number of bytes is unknown, so I'd like to use vector. But Go doesn't provide vector of byte, what can I do? And is it possible to get a slice of such a byte vector? I intends to implement data compression. Instead of store small and large number with the same number of bytes, I'm implements a variable bytes that uses less bytes with small number and more bytes with large number. My code can not compile, invalid type assertion: 1 package main 2 3 import ( 4 //"fmt" 5 "container/vector" 6 ) 7 8 func vbEncodeNumber(n uint) []byte{ 9 bytes := new(vector.Vector) 10 for { 11 bytes.Push(n % 128) 12 if n < 128 { 13 break 14 } 15 n /= 128 16 } 17 bytes.Set(bytes.Len()-1, bytes.Last().(byte)+byte(128)) 18 return bytes.Data().([]byte) // <- 19 } 20 21 func main() { vbEncodeNumber(10000) } I wish to writes a lot of such code into binary file, so I wish the func can return byte array. I haven't find a code example on vector.

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  • IIS6 compressing static files, but not JSON requests

    - by user500038
    I have IIS6 compression setup, and static content is being compressed correctly as per Coding Horror. Example of a static file: Response Headers Content-Length 55513 Content-Type application/x-javascript Content-Encoding gzip Last-Modified Mon, 20 Dec 2010 15:31:58 GMT Accept-Ranges bytes Vary Accept-Encoding Server Microsoft-IIS/6.0 X-Powered-By ASP.NET Date Wed, 29 Dec 2010 16:37:23 GMT Request Headers Accept */* Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive As you can see, the response is correctly compressed. However with a JSON call you'll see the request with the gzip parameter correctly set: Accept application/json, text/javascript, */*; q=0.01 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive X-Requested-With XMLHttpRequest Then for the response: Cache-Control private Content-Length 6811 Content-Type application/json; charset=utf-8 Server Microsoft-IIS/6.0 X-Powered-By ASP.NET X-AspNet-Version 2.0.50727 X-AspNetMvc-Version 2.0 No gzip! I found this article by Rick Stahl, which outlines how to compress in your code, but I'd like IIS to handle this. Is this possible with IIS6?

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  • Dynamically generated PDF files working in most readers except Adobe Reader

    - by Shane
    I'm trying to dynamically generate PDFs from user input, where I basically print the user input and overlay it on an existing PDF that I did not create. It works, with one major exception. Adobe Reader doesn't read it properly, on Windows or on Linux. QuickOffice on my phone doesn't read it either. So I thought I'd trace the path of me creating the files - 1 - Original PDF of background PDF 1.2 made with Adobe Distiller with the LZW encoding. I didn't make this. 2 - PDF of background PDF 1.4 made with Ghostscript. I used pdf2ps then ps2pdf on the above to strip LZW so that the reportlab and pyPDF libraries would recognize it. Note that this file looks "fuzzy," like a bad scan, in Adobe Reader, but looks fine in other readers. 3 - PDF of user-input text formatted to be combined with background PDF 1.3 made with Reportlab from user input. Opens properly and looks good in every reader I've tried. 4 - Finished PDF PDF 1.3 made from PyPDF's mergePage() function on 2 and 3. Does not open in: Adobe Reader for Windows Adobe Reader for Linux QuickOffice for Android Opens perfectly in: Google Docs' PDF viewer on the web evince for linux ghostscript viewer for linux Foxit reader for Windows Preview for Mac Are there known issues that I should know about? I don't know exactly what "flate" is, but from the internet I gather that it's some sort of open source alternative to LZW for PDF compression? Could that be causing my problem? If so, are there any libraries I could use to fix the cause in my code?

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  • How to output KML by GAE

    - by Niklas R
    Hi I use KML for a google map where entities have a geopt.db coordinate and soft memory limit was exceeded with 213.465 MB after servicing 1 requests total. The log says /list.kml 200 13130ms 10211cpu_ms 4238api_cpu_ms The file list.kml which outputs about 455,7 KB is a template as follows <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http:// www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http:// www.w3.org/2005/Atom"> <Document>{% for a in list %} <Placemark> <name> </name> <description> <![CDATA[<a href="http://{{host}}/{{a.key.id}}"> {{ a.title }} </a> <br/>{{a.text}}]]> </description> <Style> <IconStyle> <Icon> <href> http://www.google.com/intl/en_us/mapfiles/ms/icons/green-dot.png </href> </Icon> </IconStyle> </Style> <Point> <coordinates> {{a.geopt.lon|floatformat:2}},{{a.geopt.lat|floatformat:2}} </coordinates> </Point> </Placemark> {% endfor %} </Document> </kml> Is there a memory leak in the template or the python that passes the list variable? Can I improve using other template engine or other framework than default? Is kmz compression a good idea in this case? Thanks in advance for any suggestion where or how to change the code.

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  • Gzip and subprocess' stdout in python

    - by pythonic metaphor
    I'm using python 2.6.4 and discovered that I can't use gzip with subprocess the way I might hope. This illustrates the problem: May 17 18:05:36> python Python 2.6.4 (r264:75706, Mar 10 2010, 14:41:19) [GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import gzip >>> import subprocess >>> fh = gzip.open("tmp","wb") >>> subprocess.Popen("echo HI", shell=True, stdout=fh).wait() 0 >>> fh.close() >>> [2]+ Stopped python May 17 18:17:49> file tmp tmp: data May 17 18:17:53> less tmp "tmp" may be a binary file. See it anyway? May 17 18:17:58> zcat tmp zcat: tmp: not in gzip format Here's what it looks like inside less HI ^_<8B>^H^Hh<C0><F1>K^B<FF>tmp^@^C^@^@^@^@^@^@^@^@^@ which looks like it put in the stdout as text and then put in an empty gzip file. Indeed, if I remove the "Hi\n", then I get this: May 17 18:22:34> file tmp tmp: gzip compressed data, was "tmp", last modified: Mon May 17 18:17:12 2010, max compression What is going on here?

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  • Need to close a popup after javascript completes image upload then load new page

    - by Michael Robinson
    I got a problem. I have a image upload script that runs on a popup up when you select "upload button", after it is complete instead of closing it stays in the uploader.html window. I need it to close and go to a new page. Here is some of the xml that the script uses, can I change the "urlOnUploadSucess" line to close the popup and load a new page on the original page I came from? .....<upload preload="Preloading images:" upload="Uploading images to server:" prepare="Processing and image compression:" of="of" cancel="Cancel" start="Start" warning_empty_required_field="Warning! One of the required fields is empty!" confirm="Will be uploaded:"/> <urls urlToUpload="upload.php?" urlOnUploadSuccess="http://www.baublet.com/purchase.html" urlOnUploadFail="http://www.baublet.com/tryagain.html" urlUpdateFlashPlayer="http://www.baublet.com/flashalternative.html" useMessageBoxesAfterUpload="false" messageOnUploadSuccess="Images were successfully uploaded!" messageOnUploadFail="Error! Images failed to upload!" jsFunctionNameOnUpload=""/> ..... Thanks, Michael

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