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  • How to write C++ audio processing applications?

    - by cesko82
    Hi everyone, I'm an Electronics and Telecommunications student, next to my graduation. I'm gonna work on a project that involves my knowledge about DSP, music and audio in general. I allready know all the basic mathematic instruments and all the stuff I need to manage it, such as FFT, circular convolution ecc ecc. I want to learn C++ programming basically for one reason: it's very important in the professional world!!! And I think it's one of the most used to write applications working with audio, especially when it's about real time processing. Ok, after this small introduction I would like to know first, which are the most used libraries to work with audio processing in c++?? I was longer looking on the web but i couldn't find a lo of working stuff. (I work under linux with eclipse CDT enviroment). Then I would like to know if there are good sources to learn how to write some working code, such as for example how to write a simple low pass filter. Basically now i will not write real time applications, I would like to start from the processing of a WAV file, or even better an MP3 file, so basically on vectors of samples. Let's say that basically for now I would like to extract the waveform from an audio file, and save it to a thumbnail or to a PNG image. Ok, for now I think it's all I would need. Any ideas, advices, libraries, books, interesting sources about that? Thanks a lot in advance for any kind of answer. Giovanni.

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  • Converting a bash script to python (small script)

    - by Mestika
    Hi, I’ve a bash script I’ve been using for a Linux environment but now I have to use it on a Windows platform and want to convert the bash script to a python script which I can run. The bash script is rather simple (I think) and I’ve tried to convert it by google by way around but can’t convert it successfully. The bash script looks like this: runs=5 queries=50 outfile=outputfile.txt date >> $outfile echo -e "\n---------------------------------" echo -e "\n----------- Normal --------------" echo -e "\n---------------------------------" echo -e "\n----------- Normal --------------" >> $outfile for ((r = 1; r < ($runs + 1); r++)) do echo -e "Run $r of $runs\n" db2 FLUSH PACKAGE CACHE DYNAMIC python reads.py -r1 -pquery1.sql -q$queries -shotelspec -k6 -a5 >> $outfile done The main command, the python read.py … etc. is another python file I’ve been given and have the arguments as you see. I know it is a lot to ask for, but it would really help me out if someone could convert this to a python script I can use or at least give me some hints and directions. Sincerely Mestika

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  • EPIPE blocks server

    - by timn
    I have written a single-threaded asynchronous server in C running on Linux: The socket is non-blocking and as for polling, I am using epoll. Benchmarks show that the server performs fine and according to Valgrind, there are no memory leaks or other problems. The only problem is that when a write() command is interrupted (because the client closed the connection), the server will encounter a SIGPIPE. I am doing the interrupted artifically by running the benchmarking utility "siege" with the parameter -b. It does lots of requests in a row which all work perfectly. Now I press CTRL-C and restart the "siege". Sometimes I am lucky and the server does not manage to send the full response because the client's fd is invalid. As expected errno is set to EPIPE. I handle this situation, execute close() on the fd and then free the memory related to the connection. Now the problem is that the server blocks and does not answer properly anymore. Here is the strace output: accept(3, {sa_family=AF_INET, sin_port=htons(50611), sin_addr=inet_addr("127.0.0.1")}, [16]) = 5 fcntl64(5, F_GETFD) = 0 fcntl64(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 epoll_ctl(4, EPOLL_CTL_ADD, 5, {EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLET, {u32=158310248, u64=158310248}}) = 0 epoll_wait(4, {{EPOLLIN, {u32=158310248, u64=158310248}}}, 128, -1) = 1 read(5, "GET /user/register HTTP/1.1\r\nHos"..., 4096) = 161 write(5, "HTTP/1.1 200 OK\r\nContent-Type: t"..., 106) = 106 <<<<< write(5, "00001000\r\n", 10) = -1 EPIPE (Broken pipe) <<<<< Why did the previous write() work fine but not this one? --- SIGPIPE (Broken pipe) @ 0 (0) --- As you can see, the client establishes a new connection which consequently is accepted. Then, it's added to the EPOLL queue. epoll_wait() signalises that the client sent data (EPOLLIN). The request is parsed and and a response is composed. Sending the headers works fine but when it comes to the body, write() results in an EPIPE. It is not a bug in "siege" because it blocks any incoming connections, no matter from which client.

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  • Get directory path by fd

    - by tylerl
    I've run into the need to be able refer to a directory by path given its file descriptor in Linux. The path doesn't have to be canonical, it just has to be functional so that I can pass it to other functions. So, taking the same parameters as passed to a function like fstatat(), I need to be able to call a function like getxattr() which doesn't have a f-XYZ-at() variant. So far I've come up with these solutions; though none are particularly elegant. The simplest solution is to avoid the problem by calling openat() and then using a function like fgetxattr(). This works, but not in every situation. So another method is needed to fill the gaps. The next solution involves looking up the information in proc: if (!access("/proc/self/fd",X_OK)) { sprintf(path,"/proc/self/fd/%i/",fd); } This, of course, totally breaks on systems without proc, including some chroot environments. The last option, a more portable but potentially-race-condition-prone solution, looks like this: DIR* save = opendir("."); fchdir(fd); getcwd(path,PATH_MAX); fchdir(dirfd(save)); closedir(save); The obvious problem here is that in a multithreaded app, changing the working directory around could have side effects. However, the fact that it works is compelling: if I can get the path of a directory by calling fchdir() followed by getcwd(), why shouldn't I be able to just get the information directly: fgetcwd() or something. Clearly the kernel is tracking the necessary information. So how do I get to it?

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  • Best dual band A/B/G/N wireless router/ap for Linux

    - by Kevin Bowling
    Hello, I am looking for the best A/B/G/N dual band (simultaneous) router or access point that can be flashed with community firmware like dd-wrt or openwrt. In the past I have used the WRT54G series from Linksys with great success as access points and bridges. The WRT610N looks nice but I'm not sure how well the community firmwares support it. I am open to any manufacturer and any input or experience would be appreciated.

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  • How to lock screen in linux before hibernating?

    - by Emanuel Ey
    So when i hibernate my laptop the screen doesn't lock automatically. To solve this i've changed /etc/acpi/powerbtn.sh to contain: su - myUsername -c "gnome-screensaver-command -l" sudo pm-hibernate exit 0 When running this file from a command line it works as intended (ie, lock the screen and then hibernate). Unfortunately, when pressing the power button, it still just hibernates without locking the screen -what am I missing? EDIT: I've added the line whoami>>~/Desktop/test.txt to verify which user is executing the /etc/acpi/powerbtn.shscript. When pressing the power button, the file test.txt is created, but is empty. From this i conclude that the script is in fact being called when pressing the power button. What i do not understand is how the output of whoami can be empty...

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  • Linux DHCPD Mac-Address based Groups

    - by GruffTech
    Our Current DHCPD.conf looks like the following. subnet 10.0.32.0 netmask 255.255.255.0 { range 10.0.32.100 10.0.32.254; option subnet-mask 255.255.255.0; option broadcast-address 10.0.32.255; option domain-name-servers 208.67.222.222,208.67.220.220; option routers 10.0.32.5; host Dev-ABaird-W { hardware ethernet 00:1D:09:3E:49:13; fixed-address 10.0.32.94; } ... more static hosts .... } About as basic as it gets. The old router is 10.0.32.1, our company wanted to implement a squid proxy to better monitor web traffic while at work, and if necessary block large time-wasters, IE Facebook.com. However, we've quickly realized that this change has played a mean prank on our Polycom SIP Phones. Occasionally our phones will not ring, the end recipient hears ringing (this is artificially created by our PBX) however the handset never rings. The ONLY thing that has changed in our network is the option routers line. So, Since all Polycom MAC addresses begin with 00:04:F2 would it be possible in DHCP to say any 00:04:F2:::* MAC addresses get option routers 10.0.32.1, and anything else must talk with our Gateway?

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  • Linux Uninstalling errors

    - by Zack
    I want to uninstall back-track 5 so I deleted the partitions for back-track os. After deleting the partition that used to be for back-track becomes free space as in picture. But I can't delete that partition nor creating a new partition. I used G-Parted from hiren boot cd but it says there is no partition table, you need to create a partition table. But actually I have 5 partitions already. And I thought of restarting might fix it. But after showing post screen my laptop show grub error. I don't know what to do, and I tried to install back-track again to fix the problem but it also says that i do not have any partitions. I can only boot windows by passing through hiren boot cd. But most of the time My computer is not recognizing the external dvd drive, nor the internal so i have to restart again and again, hoping to catch the time computer recognize the dvd drive. Can I change the boot loader to correct the grub error? SOLVED : I have solved the grub error by writing MBR again by using EasyBCD But I still have the format error.

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  • Which Linux distributions work on IBM's JS20 PowerPC blade?

    - by Matthew Rankin
    Which Linux distributions have people successfully gotten working on an IBM JS20 Blade, which has the PowerPC 970 processor? Specifically, I'm interested in distributions other than RHEL and SLES. What gotchas need to be watched out for when installing a particular distribution of Linux on the JS20? Non-Specific Distribution Information IBM's Linux on BladeCenter JS20 IBM's eServer BladeCenter JS20 Whitepaper — "The JS20 blade supports all popular Linux distributions including Red Hat®, Inc., and SUSE LINUX." PenguinPPC Distributions List PPCLinux — "This project is a repository of information on how to run GNU/Linux on PowerPC architectures." Ubuntu Specific Information Ubuntu PowerPC FAQ — "Ubuntu 6.10 was the last officially supported PowerPC version of Ubuntu." Ubuntu PowerPC Download Ubuntu 8.04 PowerPC Supported Hardware Ubuntu 9.10 Ports — Mac (PowerPC) and IBM-PPC (POWER5) server install CD. For Apple Macintosh G3, G4, and G5 computers, including iBooks and PowerBooks as well as IBM OpenPower machines. Debian Specific Information Debian on PowerPC —"We may have a 64bit port in the future." Looks like there is only a 32-bit version available currently. Debian on JS20 blades Installing Debian Etch on IBM JS20s Gentoo Specific Information Gentoo Linux Crux PPC Specific Information Crux PPC

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  • Exception: "Given final block not properly padded" in Linux, but it works in Windows

    - by user1685364
    My application works in windows, but fails in Linux with Given final block not properly padded exception. Configuration: JDK Version: 1.6 Windows : version 7 Linux : CentOS 5.8 64bit My code is below: import java.io.IOException; import java.io.UnsupportedEncodingException; import java.security.InvalidKeyException; import java.security.Key; import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.KeyGenerator; import javax.crypto.NoSuchPaddingException; import sun.misc.BASE64Decoder; import sun.misc.BASE64Encoder; public class SecurityKey { private static Key key = null; private static String encode = "UTF-8"; private static String cipherKey = "DES/ECB/PKCS5Padding"; static { try { KeyGenerator generator = KeyGenerator.getInstance("DES"); String seedStr = "test"; generator.init(new SecureRandom(seedStr.getBytes())); key = generator.generateKey(); } catch(Exception e) { } } // SecurityKey.decodeKey("password") public static String decodeKey(String str) throws Exception { if(str == null) return str; Cipher cipher = null; byte[] raw = null; BASE64Decoder decoder = new BASE64Decoder(); String result = null; cipher = Cipher.getInstance(cipherKey); cipher.init(Cipher.DECRYPT_MODE, key); raw = decoder.decodeBuffer(str); byte[] stringBytes = null; stringBytes = cipher.doFinal(raw); // Exception!!!! result = new String(stringBytes, encode); return result; } } At the line: ciper.doFilnal(raw); the following exception is thrown: javax.crypto.BadPaddingException: Given final block not properly padded How can I fix this issue?

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  • WiFi connection help(Kali Linux)

    - by LoganR
    Ok so here's my problem. I CAN connect to my router using my passphrase. Everything goes through just fine, but I can't use anything that requires an internet connection (apt-get, Iceweasel). My router is properly configured as all other devices work fine. I can't even get into my router's configuration page or view anything else on the LAN. Also, yes I'm sure the security type is set to the correct type.

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  • Changing default openVPN IP in linux server

    - by Lamboo
    The problem is that we have a public OpenVPN service. Pay €9.95 and you get an OpenVPN account at currently half a dozen of servers for a month. This means there are always and will always be some people who create a certain amount of abuse or trouble. On the long run, the external IP every OpenVPN user gets assigned is prohibited from editing Wikipedia, it might be banned by e-gold and on some popular webforums, one-click-hosters, etc. Not a pleasant experience for the 97% of our customers who use our service responsibly and legitimately to regain their privacy. So even if I could change the assigned external IP every few months; e. g. from 216.xx.xx.164 to 216.xx.xx.170, it would help us a lot to combat this abuse and to provide our paying clients with "fresh" IP addresses that aren't banned or restricted on some popular Internet sites and services, yet. Does anybody know how to change the first IP address assigned to the public interface in CentOS? So that e.g. OpenVPN in future doesn't give our OpenVPN clients the external IP 123.xx.xx.164 but rather 123.xx.xx.170?

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  • Converting a Linux host to Virtual Machine

    - by Shyam
    On my PC I am currently running Fedora 12. I would like to convert that and the filesystem to a Virtual Machine, so that I can install Windows 7 as the main operating system and have this Fedora 12 as a VM in VMWare or VirtualBox or some such Desktop Virtualization system. Is this possible and how if yes, how?

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  • Internet cafe software for linux

    - by pehrs
    I have gotten a request to roll out a total of 8 internet cafe's in a large network. Budget is non-existent as it will all be done for a non-profit. I was planing to use Ubuntu and live-cds to minimize the amount of management required, but I can't seem to find any suitable internet cafe system that is Ubuntu based. The requirements are pretty basic: It needs to keep track of logged in time and log out users when their time it up. No billing will be done, it will just be used to ensure people can share the computers fairly. It should be possible to force logout from a central system. Users will be unskilled, so it has to have a GUI. What (preferably free, considering the shoe-string budget) software would you suggest to manage this?

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  • Kill window or application just like linux do

    - by UK
    Is there any way to kill or force closed a particular hanging window or hanging application by selecting it with some hotkey? Similar to Ctrl+Alt+Esc and select window in Ubuntu? (I may be misremembering the exact key shortcut used in Ubuntu; I just remember some key combination does that.)

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  • Detecting/Reactivating serial port that becomes inactive on Ubuntu Linux 10.10

    - by Tom
    I am using a usb2serial port to communicate with some old equipment (using my code built upon the boost asio library - I think my code is fine because it works almost all of the time). Every so often (maybe once every few days) the communication stops with my device with no error at all - the device just does not respond. I then restart my computer and everything is fine again. Does anyone know where I can start to analyse this problem? My serial port loads up fine (in /dev/ttyUSB0) and the boost library does not throw an error. The device just does not respond. If I restart the device no change - only when I restart my pc does it make a difference. I have also tried unplugging and replugging the usb connector. Does anyone know what gets cleared in the reboot (w.r.t the serial device) or what I can probe when the problem happens again (rather than just restarting with hope)

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  • Linux SVN not communicating with apache

    - by Webnet
    I have SVN setup on the server, but when I try to do a checkout remotely via SSH it throws a 200 OK response, rather than processing my checkout. I think I've missed a step with the SVN and how it communicates with apache.... any thoughts?

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  • Moving case sensitive Linux files via Windows

    - by sunwukung
    Hi the company I work for is currently trying to move a Magento installation from one server to another - however, the product images are saved in folders alphabetically indexed folders - but with an added twist, some of the letters are the same but have a different case - i.e. a, A, b, C, D, e, E, f, F, G, h, I That being the case, when we try to drag those files down from FTP in order to move them, Windows does not honour the case sensitive distinction and we are losing several image folders. Is there a simple workaround for this issue? Any help is greatly appreciated. regards SWK

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  • windows http tunnel trough 2 linux hosts?

    - by Darkmage
    the localhost only have connection to host1, Host1 have connetion to Host2 and localhost, how can i setup this to use host2 as a proxy for web trafic from localhost. i have seen similar topics but cant get it to work. how do i set it up on the XP client?

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  • Linux Kernel not passing through multicast UDP packets

    - by buecking
    Recently I've set up a new Ubuntu Server 10.04 and noticed my UDP server is no longer able to see any multicast data sent to the interface, even after joining the multicast group. I've got the exact same set up on two other Ubuntu 8.04.4 LTS machines and there is no problem receiving data after joining the same multicast group. The ethernet card is a Broadcom netXtreme II BCM5709 and the driver used is: b $ ethtool -i eth1 driver: bnx2 version: 2.0.2 firmware-version: 5.0.11 NCSI 2.0.5 bus-info: 0000:01:00.1 I'm using smcroute to manage my multicast registrations. b$ smcroute -d b$ smcroute -j eth1 233.37.54.71 After joining the group ip maddr shows the newly added registration. b$ ip maddr 1: lo inet 224.0.0.1 inet6 ff02::1 2: eth0 link 33:33:ff:40:c6:ad link 01:00:5e:00:00:01 link 33:33:00:00:00:01 inet 224.0.0.1 inet6 ff02::1:ff40:c6ad inet6 ff02::1 3: eth1 link 01:00:5e:25:36:47 link 01:00:5e:25:36:3e link 01:00:5e:25:36:3d link 33:33:ff:40:c6:af link 01:00:5e:00:00:01 link 33:33:00:00:00:01 inet 233.37.54.71 <------- McastGroup. inet 224.0.0.1 inet6 ff02::1:ff40:c6af inet6 ff02::1 So far so good, I can see that I'm receiving data for this multicast group. b$ sudo tcpdump -i eth1 -s 65534 host 233.37.54.71 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65534 bytes 09:30:09.924337 IP 192.164.1.120.58848 > 233.37.54.71.15572: UDP, length 212 09:30:09.947547 IP 192.164.1.120.58848 > 233.37.54.71.15572: UDP, length 212 09:30:10.108378 IP 192.164.1.120.58866 > 233.37.54.71.15574: UDP, length 268 09:30:10.196841 IP 192.164.1.120.58848 > 233.37.54.71.15572: UDP, length 212 ... I can also confirm that the interface is receiving mcast packets. b $ ethtool -S eth1 | grep mcast_pack rx_mcast_packets: 103998 tx_mcast_packets: 33 Now here's the problem. When I try to capture the traffic using a simple ruby UDP server I receive zero data! Here's a simple server that reads data send on port 15572 and prints the first two characters. This works on the two 8.04.4 Ubuntu Servers, but not the 10.04 server. require 'socket' s = UDPSocket.new s.bind("", 15572) 5.times do text, sender = s.recvfrom(2) puts text end If I send a UDP packet crafted in ruby to localhost, the server receives it and prints out the first two characters. So I know that the server above is working correctly. irb(main):001:0> require 'socket' => true irb(main):002:0> s = UDPSocket.new => #<UDPSocket:0x7f3ccd6615f0> irb(main):003:0> s.send("I2 XXX", 0, 'localhost', 15572) When I check the protocol statistics I see that InMcastPkts is not increasing. While on the other 8.04 servers, on the same network, received a few thousands packets in 10 seconds. b $ netstat -sgu ; sleep 10 ; netstat -sgu IcmpMsg: InType3: 11 OutType3: 11 Udp: 446 packets received 4 packets to unknown port received. 0 packet receive errors 461 packets sent UdpLite: IpExt: InMcastPkts: 4654 <--------- Same as below OutMcastPkts: 3426 InBcastPkts: 9854 InOctets: -1691733021 OutOctets: 51187936 InMcastOctets: 145207 OutMcastOctets: 109680 InBcastOctets: 1246341 IcmpMsg: InType3: 11 OutType3: 11 Udp: 446 packets received 4 packets to unknown port received. 0 packet receive errors 461 packets sent UdpLite: IpExt: InMcastPkts: 4656 <-------------- Same as above OutMcastPkts: 3427 InBcastPkts: 9854 InOctets: -1690886265 OutOctets: 51188788 InMcastOctets: 145267 OutMcastOctets: 109712 InBcastOctets: 1246341 If I try forcing the interface into promisc mode nothing changes. At this point I'm stuck. I've confirmed the kernel config has multicast enabled. Perhaps there are other config options I should be checking? b $ grep CONFIG_IP_MULTICAST /boot/config-2.6.32-23-server CONFIG_IP_MULTICAST=y Any thoughts on where to go from here?

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  • Invalid argument in sendfile() with two regular files

    - by Daniel Hershcovich
    I'm trying to test the sendfile() system call under Linux 2.6.32 to zero-copy data between two regular files. As far as I understand, it should work: ever since 2.6.22, sendfile() has been implemented using splice(), and both the input file and the output file can be either regular files or sockets. The following is the content of sendfile_test.c: #include <sys/sendfile.h> #include <fcntl.h> #include <stdio.h> int main(int argc, char **argv) { int result; int in_file; int out_file; in_file = open(argv[1], O_RDONLY); out_file = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644); result = sendfile(out_file, in_file, NULL, 1); if (result == -1) perror("sendfile"); close(in_file); close(out_file); return 0; } And when I'm running the following commands: $ gcc sendfile_test.c $ ./a.out infile The output is sendfile: Bad file descriptor Which means that the system call resulted in errno = -EINVAL, I think. What am I doing wrong?

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