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  • md5deep error with after compression and extraction

    - by Sai
    I am using md5deep to generate the checksum for the contents of an entire directory. After generation, if I use the checksum file and run a check, there are no errors. However, if I compress the file and extract it, it seems to generate an error about a missing file. The file is just called .md5. There is no file called .md5 inside the directory. It seems to create a file that is not existent. This problem exists when I use md5sum or md5deep. Any thoughts on why this is happening?

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  • Good Compression for Slow-mo Video

    - by marienbad
    What's the best way to deliver super slow-motion video to the browser? This seems to me to be a special case, because with super slow-mo video (such as 10,000 frames per second) the visual difference from frame to frame is minimal. As such, it's easy to compress highly. Please suggest codecs, as well as encoding software, backend software, software configuration tips, and services like youtube. My goal is to get about 100 frames of QVGA video to the browser in 500KB. By the way, remember that Radiohead In Rainbows site?

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  • Style sheet compression and .less add-in...updated with source

    Design time minification and .net less for style sheets.Read my previous post on this subject. http://blog.waynebrantley.com/2009/12/ultimate-automatic-stylesheet-combining.html Known IssuesIt has been reported that this does not work in 'web site project'. I do not use those anymore, not since they brought back our 'web application project'. If anyone wants to try and make it work, the...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Style sheet compression and .less add-in...updated with source

    Design time minification and .net less for style sheets.Read my previous post on this subject. http://blog.waynebrantley.com/2009/12/ultimate-automatic-stylesheet-combining.html Known IssuesIt has been reported that this does not work in 'web site project'. I do not use those anymore, not since they brought back our 'web application project'. If anyone wants to try and make it work, the...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • HTTP compression - can I configure a client to compress the data sent to a server?

    - by lgomide
    Hello, I'm using IIS 7 as web server for my application. If I enable dynamic content compression in the server, will this also enable clients to send compressed data to the server, if they can? I mean, my application uses SOAP webservices, and clients usually send large chunks of data to the server. The clients are written in C#/.NET. Is there any kind of configuration I can do in a web reference / serice reference in order to tell them to compress the content before they send it to IIS? And do I have to do any kind of configuration in IIS in order for this to work? Thanks in advance

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  • How to make 7zip faster

    - by user34463
    I normally use winRAR over 7Zip simply because its faster and only a little less efficient with compression. I did a few tests on different filetypes and sizes comparing the 7zip and winRAR default settings on their normal compression and their best compression, and in a lot of cases winRAR was 50% faster and in some it was actually 100% faster. But, I do like FOSS more. So here are my questions: Is there a way to make 7zip speed up? I'd like it to at least be on par with rar's speed Is there a way to make recovery segments in 7zip like you can in rar? I didn't see any, but I guess it could be a command line thing. I tested winrar and 7zip using the latest stable version of each (4.something with 7zip). Is the 9.x beta release noticeably faster at compression? I'm talking about faster at a comparable setting in WinRAR, not just lowering to bare minimum compression. If it matters, I use a quad core intel i7 720 (1.6ghz)/(2.8ghz) with 4gb DDR3 ram, and the 64-bit version of 7zip.

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  • How to make 7-Zip faster

    - by Matt
    I normally use WinRAR over 7-Zip simply because it's faster and only a little less efficient with compression. I did a few tests on different filetypes and sizes comparing the 7-Zip and WinRAR default settings on their normal compression and their best compression, and in a lot of cases WinRAR was 50% faster and in some it was actually 100% faster. But, I do like FOSS more. So here are my questions: Is there a way to make 7-Zip speed up? I'd like it to at least be on par with WinRAR's speed Is there a way to make recovery segments in 7-Zip like you can in WinRAR? I didn't see any, but I guess it could be a command line thing. I tested WinRAR and 7-Zip using the latest stable version of each (4-dot-something with 7-Zip). Is the 9.x beta release noticeably faster at compression? I'm talking about faster at a comparable setting in WinRAR, not just lowering to bare minimum compression. If it matters, I use a quad core Intel i7 720 (1.6 GHz)/(2.8 GHz) with 4 GB DDR3 RAM, and the 64-bit version of 7-Zip, and dual-boot Debian x64 5.0.4 and Windows 7 Home.

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  • Use ImageMagick to convert TIFF to PNGs, how to improve the speed?

    - by Woo
    I am using "convert" from IM to get PNGs from multi-page TIFF files, everything is good except the speed. From "convert" documentation, I found: For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression. The default PNG compression is 75. So I tried "-quality 0", but almost no changes with the spreed. Anyone can share the ideas of how to improve the spreed? Here are my command: convert 100Pages.tif[0,1,2,3,4,5] -quality 0 100Pages.png Thanks!

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  • Why does compressing and decompressing my SSD hard drive free up space?

    - by Paperflyer
    I bought an SSD (SandForce 2), created a tiny 25GB partition on it for Windows and installed Windows 7 64-bit. In order to free disk space, I enabled compression on the drive using the Properties entry in the context menu for the drive in Explorer. Prior to compressing I had around 5GB of free space. After compression I had 4GB, so compression was not working for me. I figured this might have happened because of the built-in data compression of the SSD. I decompressed the files again - after decompression, it left me with 7GB of free space! Better yet, after restarting, I had 10GB. What is happening here?

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  • What is recommended minimum object size for gzip performance benefits?

    - by utt73
    I'm working on improving page speed display times, and one of the methods is to gzip content from the webserver. Google recommends: Note that gzipping is only beneficial for larger resources. Due to the overhead and latency of compression and decompression, you should only gzip files above a certain size threshold; we recommend a minimum range between 150 and 1000 bytes. Gzipping files below 150 bytes can actually make them larger. We serve our content through Akamai, using their network for a proxy and CDN. What they've told me: Following up on your question regarding what is the minimum size Akamai will compress the requested object when sending it to the end user: The minimum size is 860 bytes. My reply: What is the reason(s) for why Akamai's minimum size is 860 bytes? And why, for example, is this not the case for files Akamai serves for facebook? (see below) Google recommends to gzip more agressively. And that seems appropriate on our site where the most frequent hits, by far, are AJAX calls that are <860 bytes. Akamai's response: The reasons 860 bytes is the minimum size for compression is twofold: (1) The overhead of compressing an object under 860 bytes outweighs performance gain. (2) Objects under 860 bytes can be transmitted via a single packet anyway, so there isn't a compelling reason to compress them. So I'm here for some fact checking. Is the 860 byte limit due to packet size the end of this reasoning? Why would high traffic sites push this down to the 150 byte limit... just to save on bandwidth costs (since CDNs base their charges on bandwith offloaded from origin), or is there a performance gain in doing so?

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  • Oracle Solaris 11 ZFS Lab for Openworld 2012

    - by user12626122
    Preface This is the content from the Oracle Openworld 2012 ZFS lab. It was well attended - the feedback was that it was a little short - thats probably because in writing it I bacame very time-concious after the ASM/ACFS on Solaris extravaganza I ran last year which was almost too long for mortal man to finish in the 1 hour session. Enjoy. Table of Contents Exercise Z.1: ZFS Pools Exercise Z.2: ZFS File Systems Exercise Z.3: ZFS Compression Exercise Z.4: ZFS Deduplication Exercise Z.5: ZFS Encryption Exercise Z.6: Solaris 11 Shadow Migration Introduction This set of exercises is designed to briefly demonstrate new features in Solaris 11 ZFS file system: Deduplication, Encryption and Shadow Migration. Also included is the creation of zpools and zfs file systems - the basic building blocks of the technology, and also Compression which is the compliment of Deduplication. The exercises are just introductions - you are referred to the ZFS Adminstration Manual for further information. From Solaris 11 onward the online manual pages consist of zpool(1M) and zfs(1M) with further feature-specific information in zfs_allow(1M), zfs_encrypt(1M) and zfs_share(1M). The lab is easily carried out in a VirtualBox running Solaris 11 with 6 virtual 3 Gb disks to play with. Exercise Z.1: ZFS Pools Task: You have several disks to use for your new file system. Create a new zpool and a file system within it. Lab: You will check the status of existing zpools, create your own pool and expand it. Your Solaris 11 installation already has a root ZFS pool. It contains the root file system. Check this: root@solaris:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 15.9G 6.62G 9.25G 41% 1.00x ONLINE - root@solaris:~# zpool status pool: rpool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM rpool ONLINE 0 0 0 c3t0d0s0 ONLINE 0 0 0 errors: No known data errors Note the disk device the root pool is on - c3t0d0s0 Now you will create your own ZFS pool. First you will check what disks are available: root@solaris:~# echo | format Searching for disks...done AVAILABLE DISK SELECTIONS: 0. c3t0d0 <ATA-VBOX HARDDISK-1.0 cyl 2085 alt 2 hd 255 sec 63> /pci@0,0/pci8086,2829@d/disk@0,0 1. c3t2d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@2,0 2. c3t3d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@3,0 3. c3t4d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@4,0 4. c3t5d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@5,0 5. c3t6d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@6,0 6. c3t7d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@7,0 Specify disk (enter its number): Specify disk (enter its number): The root disk is numbered 0. The others are free for use. Try creating a simple pool and observe the error message: root@solaris:~# zpool create mypool c3t2d0 c3t3d0 'mypool' successfully created, but with no redundancy; failure of one device will cause loss of the pool So destroy that pool and create a mirrored pool instead: root@solaris:~# zpool destroy mypool root@solaris:~# zpool create mypool mirror c3t2d0 c3t3d0 root@solaris:~# zpool status mypool pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c3t2d0 ONLINE 0 0 0 c3t3d0 ONLINE 0 0 0 errors: No known data errors Back to topExercise Z.2: ZFS File Systems Task: You have to create file systems for later exercises. You can see that when a pool is created, a file system of the same name is created: root@solaris:~# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 86.5K 2.94G 31K /mypool Create your filesystems and mountpoints as follows: root@solaris:~# zfs create -o mountpoint=/data1 mypool/mydata1 The -o option sets the mount point and automatically creates the necessary directory. root@solaris:~# zfs list mypool/mydata1 NAME USED AVAIL REFER MOUNTPOINT mypool/mydata1 31K 2.94G 31K /data1 Back to top Exercise Z.3: ZFS Compression Task:Try out different forms of compression available in ZFS Lab:Create 2nd filesystem with compression, fill both file systems with the same data, observe results You can see from the zfs(1) manual page that there are several types of compression available to you, set with the property=value syntax: compression=on | off | lzjb | gzip | gzip-N | zle Controls the compression algorithm used for this dataset. The lzjb compression algorithm is optimized for performance while providing decent data compression. Setting compression to on uses the lzjb compression algorithm. The gzip compression algorithm uses the same compression as the gzip(1) command. You can specify the gzip level by using the value gzip-N where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the default for gzip(1)). Create a second filesystem with compression turned on. Note how you set and get your values separately: root@solaris:~# zfs create -o mountpoint=/data2 mypool/mydata2 root@solaris:~# zfs set compression=gzip-9 mypool/mydata2 root@solaris:~# zfs get compression mypool/mydata1 NAME PROPERTY VALUE SOURCE mypool/mydata1 compression off default root@solaris:~# zfs get compression mypool/mydata2 NAME PROPERTY VALUE SOURCE mypool/mydata2 compression gzip-9 local Now you can copy the contents of /usr/lib into both your normal and compressing filesystem and observe the results. Don't forget the dot or period (".") in the find(1) command below: root@solaris:~# cd /usr/lib root@solaris:/usr/lib# find . -print | cpio -pdv /data1 root@solaris:/usr/lib# find . -print | cpio -pdv /data2 The copy into the compressing file system takes longer - as it has to perform the compression but the results show the effect: root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.35G 1.59G 31K /mypool mypool/mydata1 1.01G 1.59G 1.01G /data1 mypool/mydata2 341M 1.59G 341M /data2 Note that the available space in the pool is shared amongst the file systems. This behavior can be modified using quotas and reservations which are not covered in this lab but are covered extensively in the ZFS Administrators Guide. Back to top Exercise Z.4: ZFS Deduplication The deduplication property is used to remove redundant data from a ZFS file system. With the property enabled duplicate data blocks are removed synchronously. The result is that only unique data is stored and common componenents are shared. Task:See how to implement deduplication and its effects Lab: You will create a ZFS file system with deduplication turned on and see if it reduces the amount of physical storage needed when we again fill it with a copy of /usr/lib. root@solaris:/usr/lib# zfs destroy mypool/mydata2 root@solaris:/usr/lib# zfs set dedup=on mypool/mydata1 root@solaris:/usr/lib# rm -rf /data1/* root@solaris:/usr/lib# mkdir /data1/2nd-copy root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02M 2.94G 31K /mypool mypool/mydata1 43K 2.94G 43K /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1 2142768 blocks root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02G 1.99G 31K /mypool mypool/mydata1 1.01G 1.99G 1.01G /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1/2nd-copy 2142768 blocks root@solaris:/usr/lib#zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.99G 1.96G 31K /mypool mypool/mydata1 1.98G 1.96G 1.98G /data1 You could go on creating copies for quite a while...but you get the idea. Note that deduplication and compression can be combined: the compression acts on metadata. Deduplication works across file systems in a pool and there is a zpool-wide property dedupratio: root@solaris:/usr/lib# zpool get dedupratio mypool NAME PROPERTY VALUE SOURCE mypool dedupratio 4.30x - Deduplication can also be checked using "zpool list": root@solaris:/usr/lib# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT mypool 2.98G 1001M 2.01G 32% 4.30x ONLINE - rpool 15.9G 6.66G 9.21G 41% 1.00x ONLINE - Before moving on to the next topic, destroy that dataset and free up some space: root@solaris:~# zfs destroy mypool/mydata1 Back to top Exercise Z.5: ZFS Encryption Task: Encrypt sensitive data. Lab: Explore basic ZFS encryption. This lab only covers the basics of ZFS Encryption. In particular it does not cover various aspects of key management. Please see the ZFS Adminastrion Manual and the zfs_encrypt(1M) manual page for more detail on this functionality. Back to top root@solaris:~# zfs create -o encryption=on mypool/data2 Enter passphrase for 'mypool/data2': ******** Enter again: ******** root@solaris:~# Creation of a descendent dataset shows that encryption is inherited from the parent: root@solaris:~# zfs create mypool/data2/data3 root@solaris:~# zfs get -r encryption,keysource,keystatus,checksum mypool/data2 NAME PROPERTY VALUE SOURCE mypool/data2 encryption on local mypool/data2 keysource passphrase,prompt local mypool/data2 keystatus available - mypool/data2 checksum sha256-mac local mypool/data2/data3 encryption on inherited from mypool/data2 mypool/data2/data3 keysource passphrase,prompt inherited from mypool/data2 mypool/data2/data3 keystatus available - mypool/data2/data3 checksum sha256-mac inherited from mypool/data2 You will find the online manual page zfs_encrypt(1M) contains examples. In particular, if time permits during this lab session you may wish to explore the changing of a key using "zfs key -c mypool/data2". Exercise Z.6: Shadow Migration Shadow Migration allows you to migrate data from an old file system to a new file system while simultaneously allowing access and modification to the new file system during the process. You can use Shadow Migration to migrate a local or remote UFS or ZFS file system to a local file system. Task: You wish to migrate data from one file system (UFS, ZFS, VxFS) to ZFS while mainaining access to it. Lab: Create the infrastructure for shadow migration and transfer one file system into another. First create the file system you want to migrate root@solaris:~# zpool create oldstuff c3t4d0 root@solaris:~# zfs create oldstuff/forgotten Then populate it with some files: root@solaris:~# cd /var/adm root@solaris:/var/adm# find . -print | cpio -pdv /oldstuff/forgotten You need the shadow-migration package installed: root@solaris:~# pkg install shadow-migration Packages to install: 1 Create boot environment: No Create backup boot environment: No Services to change: 1 DOWNLOAD PKGS FILES XFER (MB) Completed 1/1 14/14 0.2/0.2 PHASE ACTIONS Install Phase 39/39 PHASE ITEMS Package State Update Phase 1/1 Image State Update Phase 2/2 You then enable the shadowd service: root@solaris:~# svcadm enable shadowd root@solaris:~# svcs shadowd STATE STIME FMRI online 7:16:09 svc:/system/filesystem/shadowd:default Set the filesystem to be migrated to read-only root@solaris:~# zfs set readonly=on oldstuff/forgotten Create a new zfs file system with the shadow property set to the file system to be migrated: root@solaris:~# zfs create -o shadow=file:///oldstuff/forgotten mypool/remembered Use the shadowstat(1M) command to see the progress of the migration: root@solaris:~# shadowstat EST BYTES BYTES ELAPSED DATASET XFRD LEFT ERRORS TIME mypool/remembered 92.5M - - 00:00:59 mypool/remembered 99.1M 302M - 00:01:09 mypool/remembered 109M 260M - 00:01:19 mypool/remembered 133M 304M - 00:01:29 mypool/remembered 149M 339M - 00:01:39 mypool/remembered 156M 86.4M - 00:01:49 mypool/remembered 156M 8E 29 (completed) Note that if you had created /mypool/remembered as encrypted, this would be the preferred method of encrypting existing data. Similarly for compressing or deduplicating existing data. The procedure for migrating a file system over NFS is similar - see the ZFS Administration manual. That concludes this lab session.

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  • What is recommended minimum object size for gzip benefits?

    - by utt73
    I'm working on improving page speed display times, and one of the methods is to gzip content from the webserver. Google recommends: Note that gzipping is only beneficial for larger resources. Due to the overhead and latency of compression and decompression, you should only gzip files above a certain size threshold; we recommend a minimum range between 150 and 1000 bytes. Gzipping files below 150 bytes can actually make them larger. We serve our content through Akamai, using their network for a proxy and CDN. What they've told me: Following up on your question regarding what is the minimum size Akamai will compress the requested object when sending it to the end user: The minimum size is 860 bytes. My reply: What is the reason(s) for why Akamai's minimum size is 860 bytes? And why, for example, is this not the case for files Akamai serves for facebook? (see below) Google recommends to gzip more agressively. And that seems appropriate on our site where the most frequent hits, by far, are AJAX calls that are <860 bytes. Akamai's response: The reasons 860 bytes is the minimum size for compression is twofold: (1) The overhead of compressing an object under 860 bytes outweighs performance gain. (2) Objects under 860 bytes can be transmitted via a single packet anyway, so there isn't a compelling reason to compress them. So I'm here for some fact checking. Is the 860 byte limit due to packet size the end of this reasoning? Why would high traffic sites push this lower/closer to the 150 byte limit... just to save on bandwidth costs, or is there a performance gain in doing so?

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  • Compressing/compacting messages over websocket on Node.js

    - by icelava
    We have a websocket implementation (Node.js/Sock.js) that exchanges data as JSON strings. As our use cases grow, so have the size of the data transmitted across the wire. The websocket protocol does not natively offer any compression feature, so in order to reduce the size of our messages we'd have to manually do something about the serialisation. There appear to be a variety of LZW implementations in Javascript, some which confuses me on their compatibility for in-browser use only versus transmission across the wire due to my lack of understanding on low-level encodings. More importantly, all of them seem to take a noticeable performance drag when Javascript is the engine doing the compression/decompression work, which is not desirable for mobile devices. Looking instead other forms of compact serialisation, MessagePack does not appear to have any active support in Javascript itself; BSON does not have any Javascript implementation; and an alternative BISON project that I tested does not deserialise everything back to their original values (large numbers), and it does not look like any further development will happen either. What are some other options others have explored for Node.js?

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  • Optimize video filesize without quality loss

    - by user12015
    Is there a simple way (on the command line - I want to write a script which compresses all videos in a folder) to reduce the filesize of a video (almost) without quality loss? Is there a method which works equally well for different video format (mp4, flv, m4v, mpg, mov, avi)? I should mention that most of the videos I would like to compress are downloaded web-videos (mp4, flv), so it's not clear if there is much room for further compression.

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  • UTF-8 to ISO-8859-1 mapping / lossless conversion libraries in Java

    - by Pawel Krupinski
    I need to perform a conversion of characters from UTF-8 to ISO-8859-1 in Java without losing for example all of the UTF-8 specific punctuation. Ideally would like these to be converted to equivalents in ISO (e.g. there are probably 5 different single quotes in UTF-8 and would like them all converted to ISO single quote character). String.getBytes("ISO-8859-1") just won't do the trick in this case as it will lose the UTF-8-specific chars. Do you know of any ready mappings or libraries in Java that would map UTF-8 specific characters to ISO?

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  • Anyone have any opinions about Chilkatsoft? [closed]

    - by Joe Enos
    I'm considering purchasing the Chilkatsoft bundle, which includes a bunch of libraries on lots of technologies. Specifically, I care about .NET compression, encryption, FTP, and mail libraries, but I'm interested in looking at the rest of their stuff as well. Does anyone have any experience using these libraries, or opinions on the company or product in general? The price is right, and the content seems good, so I just want to make sure I do my homework before purchasing. Thanks

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  • Decoding a compressed short string; uncertain on compression used - Updated

    - by James
    Hi, I have a program that is compressing a string in an unknown way. I know a few inputs and the output produced, but I am not sure what is being used to compress the string. Here are my examples. (just 38 x a, no spaces or anything else) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "026900211AA63000026900"   (just 32 x a) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" Out: "0209001c1aa7a000020900" (31 x a, then 1 b) In: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab" Out: "0209000177c553c000020900" (31 x b, then 1 a) In: "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbba" Out: "0209001e7754f38000020900" In: "Hey wot u doing 2day u wanna do something" Out: "02990011C7C62E78CE6B8E3ACD83E81B37C5C5A6B9D1E1B06963DB5E71155C1000029900" (same as previous string, but with a space at the end) In: "Hey wot u doing 2day u wanna do something " Out: "02A90012C7718B9E339AE2EB360FA02CDF17177A674786DF4B1EDAF388AAE08000000002A90000" The only definite thing I can see so far is digit 2 and 3 are the amount of characters (hex value), ie first one is 26 = 38 Also the first 6 digits are repeated at the end Any help / advice would be great, thanks!

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  • What are the benefits of the PHP the different PHP compression libraries?

    - by Christopher W. Allen-Poole
    I've been looking into ways to compress PHP libraries, and I've found several libraries which might be useful, but I really don't know much about them. I've specifically been reading about bcompiler and PHAR libraries. Is there any performance benefit in either of these? Are there any "gotchas" I need to watch out for? What are the relative benefits? Do either of them add to/detract from performance? I'm also interested in learning of other libs which might be out there which are not obvious in the documentation? As an aside, does anyone happen to know whether these work more like zip files which just happen to have the code in there, or if they operate more like Python's pre-compiling which actually runs a pseudo-compiler? ======================= EDIT ======================= I've been asked, "What are you trying to accomplish?" Well, I suppose the answer is that this is all hypothetical. It is a combination of these: What if my pet project becomes the most popular web project on earth and I want to distribute it quickly and easily? (hay, a man can dream, right?) It also seems if using PHAR can be done easily, it would be the best way to create a subversion snapshot. Python has this really cool pre-compiling policy, I wonder if PHP has something like that? These libraries seem to do something similar. Will they do that? Hey, these libraries seem pretty neat, but I'd like clarification on the differences as they seem to do the same thing

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  • Arithmetic Coding Questions

    - by Xophmeister
    I have been reading up on arithmetic coding and, while I understand how it works, all the guides and instructions I've read start with something like: Set up your intervals based upon the frequency of symbols in your data; i.e., more likely symbols get proportionally larger intervals. My main query is, once I have encoded my data, presumably I also need to include this statistical model with the encoding, otherwise the compressed data can't be decoded. Is that correct? I don't see this mentioned anywhere -- the most I've seen is that you need to include the number of iterations (i.e., encoded symbols) -- but unless I'm missing something, this also seems necessary to me. If this is true, that will obviously add an overhead to the final output. At what point does this outweigh the benefits of compression (e.g., say if I'm trying to compress just a few thousand bits)? Will the choice of symbol size also make a significant difference (e.g., if I'm looking at 2-bit words, rather than full octets/whatever)?

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  • Ogre3D : seeking advices about game files management

    - by Tibor
    I'm working on a new game, and its related level editor, based on Ogre3D. I was thinking about how i could manage the game files, knowing that Ogre use .mesh files for models, .material for materials/texture information etc... . At first i thought about a common .zip folder decompressed at runtime (the same way Torchlight and Ogre samples do). But this way the game assets become a monolithic archive, loading takes time, and could be difficult to eventually patch them. So, let's say i have a game object named "Cube" i want to load in my program. Going for modularity, what if i create a compressed file (using zlib compression routines) named Cube.extname, containing its sub-files Cube.mesh, Cube.material and so on ? Are there any alternatives or should i stick with compressed objects? PS: Just to clear things, the answer is unrelated to my program code, at the moment i'm using "resources.cfg" pointing to the OgreSDK media directory.

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  • Photo sharing social platform [closed]

    - by user1696497
    I am working on a photo sharing social platform like Flickr, Photobucket. To start off with I have half a million photos as of now. I want to convert all of these into a single format, compression ratio and use it as an original image. I will be storing original image, re-sized image according to layout and a thumbnail. I have started off with ruby, didn't find supporting libraries. I am considering python as it has a good image processing library and instagram is using it. I want some advise about how the image has to be processed while uploading, efficient way of storage whether database or a file system, image compressions, and precautions to be taken. I would be having profile pictures, do I need store them separately or along with the images? If I want to store the images on a file system, which file system should I use and also should I store the url or should I use any intermediate key value store like redis?

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  • ?????????????????~BI/DWH????????(2)

    - by Yusuke.Yamamoto
    Oracle Database ???BI???????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????! ??????????(04:19)????????????? Enterprise Manager ?????????????????????????? ???????????????????? Enterprise Manager ??SQL????????????????????I/O?????????? ??????????????Oracle GRID Center ??????????????? ????????????????????????? ????????DWH????????????????·???????? ???? ???????/???????!! ???????????? ~????·???????????????~ ????????: Advanced Compression|??????????? Oracle Enterprise Manager|??????????? DWH(?????????)??·??

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  • how do i determine the image compression algorithm

    - by klijo
    i have a folder containing images. I need to determine the image compression algorithm used in them. Image format is TIFF. Is there a program that i can use to do this ? A program that runs on windows or Linux is ok. When i do a file it gives 100 (2).tif: TIFF image data, little-endian 100.tif: TIFF image data, little-endian It doesnt say which type of algorithm it uses. whether its lossy or lossless and the name of it ?

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  • Can compressing Program Files save space *and* give a significant boost to SSD performance?

    - by Christopher Galpin
    Considering solid-state disk space is still an expensive resource, compressing large folders has appeal. Thanks to VirtualStore, could Program Files be a case where it might even improve performance? Discovery In particular I have been reading: SSD and NTFS Compression Speed Increase? Does NTFS compression slow SSD/flash performance? Will somebody benchmark whole disk compression (HD,SSD) please? (may have to scroll up) The first link is particularly dreamy, but maybe head a little too far in the clouds. The third link has this sexy semi-log graph (logarithmic scale!). Quote (with notes): Using highly compressable data (IOmeter), you get at most a 30x performance increase [for reads], and at least a 49x performance DECREASE [for writes]. Assuming I interpreted and clarified that sentence correctly, this single user's benchmark has me incredibly interested. Although write performance tanks wretchedly, read performance still soars. It gave me an idea. Idea: VirtualStore It so happens that thanks to sanity saving security features introduced in Windows Vista, write access to certain folders such as Program Files is virtualized for non-administrator processes. Which means, in normal (non-elevated) usage, a program or game's attempt to write data to its install location in Program Files (which is perhaps a poor location) is redirected to %UserProfile%\AppData\Local\VirtualStore, somewhere entirely different. Thus, to my understanding, writes to Program Files should primarily only occur when installing an application. This makes compressing it not only a huge source of space gain, but also a potential candidate for performance gain. Testing The beginning of this post has me a bit timid, it suggests benchmarking NTFS compression on a whole drive is difficult because turning it off "doesn't decompress the objects". However it seems to me the compact command is perfectly capable of doing so for both drives and individual folders. Could it be only marking them for decompression the next time the OS reads from them? I need to find the answer before I begin my own testing.

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