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  • Is it possible to have anonymous purchases with ubercart without the creation of a new user account?

    - by DKinzer
    I would like to be able to have anonymous users purchase a product but not have a new account created when they purchase it. Unfortunately the creation of a new user seems to be very tightly integrated into ubercart's ordering system. And, because the order module is part of the ubercart core, it's behavior cannot be overridden easily. One possibility for overriding is the creation of a new user account by supplying ubercart with an bogus anonymous account: hook into hook_form_alter at $form_id == 'uc_cart_checkout_review_form' because this is where ubercart first associates the $order to an uid. Add our submit function to the queue: //Find out if the user is anonymous: global $user; if ($user->uid == 0 ) { //Load a previously created anonymous user account $anonymous_user = mymodule_get_anonymous_user(); //create the order and assign our anonymous_user_id to it $order = uc_order_load($_SESSION['cart_order']); $order->uid = $anonymous_user->uid; uc_order_save($order); //Assign the global user our anonymous user uid $user->uid = $anonymous_user->uid; } But what I really need is to be able to have an anonymous purchase without being forced to create a new account, this solution does not work for me. Apart from which, using this technique will automatically login the anonymous_user into our bogus_anonymous_user account. Which is definitely something I don't want. Is there a better non-duct-tape way around the creation of a new user account for anonymous purchases in ubercart?. AND FYI - at this point I'm kind of stuck with ubercart so I cannot use something else. Thanks! D

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  • Advice on designing and building distributed application to track vehicles

    - by dario-g
    I'm working on application for tracking vehicles. There will be about 10k or more vehicles. Each will be sending ~250bytes in each minute. Data contains gps location and everything from CAN Bus (every data that we can read from vehicle computer and dashboard). Data are sent by GSM/GPRS (using UDP protocol). Estimated rows with this data per day is ~2000k. I see there 3 main blocks. 1. Multithreaded Socket Server (MSS) - I have it. MSS stores received data to the queue (using NServiceBus). 2. Rule Processor Server (RPS) - this is core of this system. This block is responsible for parsing received data, storing in the database, processing rules, sending messages to Notifier Server (this will be sending e-mails/sms texts). Rule example. As I said between received bytes there will be information about current speed. When speed will be above 120 then: show alert in web application for specified users, send e-mail, send sms text. (There can be more than one instance of RPS). 3. Web application - allows reporting and defining rules by users, monitoring alerts, etc. I'm looking for advice how to design communication between RPS and Web application. Some questions: - Should Web application and RPS have separated databases or one central database will be enough? I have one domain model in web application. If there will be one central database then can I use the same model (objects) on RPS? So, how to send changed rules to RPS? I try to decouple this blocks as much as possible. I'm planning to create different instance of application for each client (each client will have separated database). One client will be have 10k vehicles, others only 100 vehicles.

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  • Windows Messages Bizarreness

    - by jameszhao00
    Probably just a gross oversight of some sort, but I'm not receiving any WM_SIZE messages in the message loop. However, I do receive them in the WndProc. I thought the windows loop gave messages out to WndProc? LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam ) { switch(message) { // this message is read when the window is closed case WM_DESTROY: { // close the application entirely PostQuitMessage(0); return 0; } break; case WM_SIZE: return 0; break; } printf("wndproc - %i\n", message); // Handle any messages the switch statement didn't return DefWindowProc (hWnd, message, wParam, lParam); } ... and now the message loop... while(TRUE) { // Check to see if any messages are waiting in the queue if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { // translate keystroke messages into the right format TranslateMessage(&msg); // send the message to the WindowProc function DispatchMessage(&msg); // check to see if it's time to quit if(msg.message == WM_QUIT) { break; } if(msg.message == WM_SIZING) { printf("loop - resizing...\n"); } } else { //do other stuff } }

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  • How to recursive rake? -- or suitable alternatives

    - by TerryP
    I want my projects top level Rakefile to build things using rakefiles deeper in the tree; i.e. the top level rakefile says how to build the project (big picture) and the lower level ones build a specific module (local picture). There is of course a shared set of configuration for the minute details of doing that whenever it can be shared between tasks: so it is mostly about keeping the descriptions of what needs building, as close to the sources being built. E.g. /Source/Module/code.foo and cie should be built using the instructions in /Source/Module/Rakefile; and /Rakefile understands the dependencies between modules. I don't care if it uses multiple rake processes (ala recursive make), or just creates separate build environments. Either way it should be self-containable enough to be processed by a queue: so that non-dependent modules could be built simultaneously. The problem is, how the heck do you actually do something like that with Rake!? I haven't been able to find anything meaningful on the Internet, nor in the documentation. I tried creating a new Rake::Application object and setting it up, but whatever methods I try invoking, only exceptions or "Don't know how to build task ':default'" errors get thrown. (Yes, all rakefiles have a :default). Obviously one could just execute 'rake' in a sub directory for a :modulename task, but that would ditch the options given to the top level; e.g. think of $(MAKE) and $(MAKEFLAGS). Anyone have a clue on how to properly do something like a recursive rake?

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  • Radix Sort in Python [on hold]

    - by Steven Ramsey
    I could use some help. How would you write a program in python that implements a radix sort? Here is some info: A radix sort for base 10 integers is a based on sorting punch cards, but it turns out the sort is very ecient. The sort utilizes a main bin and 10 digit bins. Each bin acts like a queue and maintains its values in the order they arrive. The algorithm begins by placing each number in the main bin. Then it considers the ones digit for each value. The rst value is removed and placed in the digit bin corresponding to the ones digit. For example, 534 is placed in digit bin 4 and 662 is placed in the digit bin 2. Once all the values in the main bin are placed in the corresponding digit bin for ones, the values are collected from bin 0 to bin 9 (in that order) and placed back in the main bin. The process continues with the tens digit, the hundreds, and so on. After the last digit is processed, the main bin contains the values in order. Use randint, found in random, to create random integers from 1 to 100000. Use a list comphrension to create a list of varying sizes (10, 100, 1000, 10000, etc.). To use indexing to access the digits rst convert the integer to a string. For this sort to work, all numbers must have the same number of digits. To zero pad integers with leading zeros, use the string method str.zfill(). Once main bin is sorted, convert the strings back to integers. I'm not sure how to start this, Any help is appreciated. Thank you.

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  • Passing Variable Length Arrays to a function

    - by David Bella
    I have a variable length array that I am trying to pass into a function. The function will shift the first value off and return it, and move the remaining values over to fill in the missing spot, putting, let's say, a -1 in the newly opened spot. I have no problem passing an array declared like so: int framelist[128]; shift(framelist); However, I would like to be able to use a VLA declared in this manner: int *framelist; framelist = malloc(size * sizeof(int)); shift(framelist); I can populate the arrays the same way outside the function call without issue, but as soon as I pass them into the shift function, the one declared in the first case works fine, but the one in the second case immediately gives a segmentation fault. Here is the code for the queue function, which doesn't do anything except try to grab the value from the first part of the array... int shift(int array[]) { int value = array[0]; return value; } Any ideas why it won't accept the VLA? I'm still new to C, so if I am doing something fundamentally wrong, let me know.

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  • Singleton Issues in iOS http client

    - by Andrew Lauer Barinov
    I implemented an HTTP client is iOS that is meant to be a singleton. It is a subclass of AFNetworking's excellent AFHTTPClient My access method is pretty standard: + (LBHTTPClient*) sharedHTTPClient { static dispatch_once_t once = 0; static LBHTTPClient *sharedHTTPClient = nil; dispatch_once(&once, ^{ sharedHTTPClient = [[LBHTTPClient alloc] initHTTPClient]; }); return sharedHTTPClient; } // my init method - (id) initHTTPClient { self = [super initWithBaseURL:[NSURL URLWithString:kBaseURL]]; if (self) { // Sub class specific initializations } return self; } Super's init method is very long, and can be found here However the problem I experience is when the dispatch_once queue is run, the app locks and become unresponsive. When I step through code, I notice that it locks on dispatch_once and then remains frozen. Is this something to do with the main thread locking down? How come it stays locked like that? Also, none of the HTTP client methods fire. Stepping through the code some more, I find this line in dispatch/once.h is where the app locks down: DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL_ALL DISPATCH_NOTHROW void _dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) { if (DISPATCH_EXPECT(*predicate, ~0l) != ~0l) { dispatch_once(predicate, block); // App locks here } }

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  • Closing Connections on asynchronous messaging in JMS

    - by The Elite Gentleman
    Hi Everyone! I have created a JMS wrapper (similar to Springs JmsTemplate since I'm not using Springs) and I was wondering: If I setup asynchronous messaging, when is a good time to close connections and JMS relates resources (so that the Connection Factory in the Resource Pool can be available)? Thanks Here's the source code for receiving JMS messages public Message receive() throws JMSException { QueueConnection connection = null; QueueSession session = null; QueueReceiver consumer = null; try { // TODO Auto-generated method stub connection = factory.createQueueConnection(); if (connection != null && getExceptionListener() != null) { connection.setExceptionListener(getExceptionListener()); } session = connection.createQueueSession(isSessionTransacted(), getAcknowledgeMode()); consumer = session.createReceiver(queue); if (getMessageListener() != null) { consumer.setMessageListener(getMessageListener()); } //Begin connection.start(); if (getMessageListener() == null) { return null; } return receive(session, consumer); } catch (JMSException e) { // TODO: handle exception logger.error(e.getLocalizedMessage(), e); throw e; } finally { JMSUtil.closeMessageConsumer(consumer); JMSUtil.closeSession(session, false); //false = don't commit. JMSUtil.closeConnection(connection, true); //true = stop before close. } As you can see, if getMessageListener() != null then apply it to the MessageConsumer. Am I doing this correctly? The same approach has also been taken for JMS Topic.

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  • Maximizing the number of true concurrent / parrallel http requests in Silverlight

    - by Clems
    Hi all. I'm using SL 4 beta and my app needs to do a lot of small http requests to the server. I believe that when exceeding the number of allowed concurrent requests, the subsequent requests are put in a queue. I am also aware that SL 4 has both a http browser stack and a http client stack, with both different limit in terms of the number of concurrent requests. Let's say call those limits MAX_BROWSER and MAX_CLIENT. Also I think I read somewhere that the number of concurrent requests is limited per domain, not overall. But I'm sure if this applies to both the http client stack. That means that you CAN have MAX_BROWSER requests to domain1.com AND MAX_BROWSER requests to domain2.com at the same time. And I even believe that sub domains are considered different so you can also have MAX_BROWSER requests to domain1.com AND MAX_BROWSER requests to sub.domain1.com at the same time. I have ownership of the services and domain names so I could easily setup sub domains for my services. Given those considerations I'm trying to optimize the number of concurrent http requests to my server. Here are few questions ? Is is possible to use both stack at the same time ? Is the subdomain/domain story true for both stacks ? None ? If so that would mean that I could potentially have a number of concurrent requests equal to : (MAX_BROWSER + MAX_CLIENT) * NUMBER_OF_DOMAINS which would be fairly good. Is this correct ? I'm kind of sharing my morning thoughts here, hoping somebody has experimented with those things. Thank you.

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  • Google App Engine Needs Index Error

    - by Andrew Johnson
    I am currently getting a needs index error on my app engine app: http://www.gaiagps.com/wiki/home. I believe this index should have been created automatically by my index.yaml file (see below). Googling a bit, I think I just need to wait for my index to be built. Is this correct, or do I need to do something manually? Is there some sort of index-building queue? My tables are very, very small right now. EDIT: I added the line "indexes:" to my app.yaml, and now app engine reports the index is building, so I think this is fixed. It's weird that this file was wrong considering I've never touched it. indexes: # AUTOGENERATED # This index.yaml is automatically updated whenever the dev_appserver # detects that a new type of query is run. If you want to manage the # index.yaml file manually, remove the above marker line (the line # saying "# AUTOGENERATED"). If you want to manage some indexes # manually, move them above the marker line. The index.yaml file is # automatically uploaded to the admin console when you next deploy # your application using appcfg.py. - kind: Revision properties: - name: name - name: created The app works on my dev server, but not in production. However, on my dev console, I have noticed this error (EDIT: THIS ERROR IS GONE NOW THAT I ADDED indexes: to the app.yaml file above): ERROR 2009-10-18 04:46:51,908 dev_appserver_index.py:176] Error parsing /gaiagps.com/index.yaml: 'NoneType' object is not callable in "<string>", line 13, column 3: - kind: Revision ^

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  • Can any linux API or tool watch for any change in any folder below e.g. /SharedRoot or do I have to

    - by Simon B.
    I have a folder with ~10 000 subfolders. Can any linux API or tool watch for any change in any folder below e.g. /SharedRoot or do I have to setup inotify for each folder? (i.e. I loose if I want to do this for 10k+ folders). I guess yes, since I've already seen examples of this inefficient method, for instance http://twistedmatrix.com/trac/browser/trunk/twisted/internet/inotify.py?rev=28866#L345 My problem: I need to keep folders time-sorted with most recently active "project" up top. When a file changes, each folder above that file should update its last-modified timestamp to match the file. Delays are ok. Opening a file (typically MS Excel) and closing again, its file date can jump up and then down again. For this reason I need to wait until after a file is closed, then queue the folder of that file for checking, and only a while later do I go and look for the newest file in its folder, since the filedate of the triggering file could already be back-dated to its original timestamp by Excel or similar programs. Also in case several files from same folder are used/created, it makes sense to buffer timestamping of that folders' parents to at least get a bunch of updates collapsed into one delayed update. I'm looking for a linux solution. I have some code that can be run on a windows server, most of the queing functionality is here: http://github.com/sesam/FolderdateFollowsFiles/blob/master/FolderdateFollowsFiles/Follower.vb Available API:s The relative of inotify on windows, ReadDirectoryChangesW, can watch a folder and its whole subtree; see bWatchSubtree on http://msdn.microsoft.com/en-us/library/aa365465(VS.85).aspx Samba? Patching samba source is a possibility, but perhaps there are already hooks available? Other possibilities, like client side (various windows versions) and spying on file activities in order to update folders recursively?

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  • Double buffering C#

    - by LmSNe
    Hey, I'm trying to implement the following method: void Ball::DrawOn(Graphics g); The method should draw all previous locations(stored in a queue) of the ball and finally the current location. I don't know if that matters, but I print the previous locations using g.DrawEllipse(...) and the current location using g.FillEllipse(...). The question is, that as you could imagine there is a lot of drawing to be done and thus the display starts to flicker much. I had searched for a way to double buffer, but all I could find is these 2 ways: 1) System.Windows.Forms.Control.DoubleBuffered = true; 2) SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true); while trying to use the first, I get the an error explaining that from in this method the Property DoubleBuffered is inaccessible due to its protection level. While I can't figure how to use the SetStyle method. Is it possible at all to double buffer while all the access I have is to the Graphics Object I get as input in the method? Thanks in Advance,

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  • Apache Tuscany 1.6 How do you set the JMS Binding Delivery Mode to NON_PERSISTENT?

    - by Robert Greiner
    I am using Tuscany 1.6 and am trying to set the Delivery Mode JMS Binding to NON_PERSISTENT. I've tried using uri="jms:MyService?deliveryMode=1" (which is what the spec (PDF) says to do) but, I ended up getting the following exception: Unknown token deliveryMode=1 I also tried <headers JMSDeliveryMode="NON_PERSISTENT"/>, although I did not get an exception the messages still got delivered as PERSISTENT. This is the format for the URI jms:<jms-dest>? connectionFactoryName=<Connection-Factory-Name> & destinationType={queue|topic} deliveryMode=<Delivery-Mode> & timeToLive=<Time-To-Live> & priority=<Priority> & <User-Property>=<User-Property-Value> & … This is the example I am using <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="MyValueComposite"> <service name="MyValueService"> <interface.java interface="services.myvalue.MyValueService"/> <binding.jms uri="jms:MyValueServiceQueue?activationSpecName=MyValueServiceAS&... "/> </service> <reference name="StockQuoteService"> <interface.java interface="services.stockquote.StockQuoteService"/> <binding.jms uri="jms:StockQuoteServiceQueue?connectionFactoryName=StockQuoteServiceQCF&deliveryMode=1&... "/> </reference> </composite>

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  • BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding

    - by Tim
    Mr. Ayende wrote in his latest blog post about an implementation of a queue. In the post he's using two magical files: BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding BinaryWriterWith7BitEncoding can write both int and long? using the following method signatures: void WriteBitEncodedNullableInt64(long? value) & void Write7BitEncodedInt(int value) and BinaryReaderWith7BitEncoding can read the values written using the following method signatures: long? ReadBitEncodedNullableInt64() and int Read7BitEncodedInt() So far I've only managed to find a way to read the 7BitEncodedInt: protected int Read7BitEncodedInt() { int value = 0; int byteval; int shift = 0; while(((byteval = ReadByte()) & 0x80) != 0) { value |= ((byteval & 0x7F) << shift); shift += 7; } return (value | (byteval << shift)); } I'm not too good with byte shifting - does anybody know how to read and write the 7BitEncoded long? and write the int ?

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  • How to perform undirected graph processing from SQL data

    - by recipriversexclusion
    I ran into the following problem in dynamically creating topics for our ActiveMQ system: I have a number of processes (M_1, ..., M_n), where n is not large, typically 5-10. Some of the processes will listen to the output of others, through a message queue; these edges are specified in an XML file, e.g. <link from="M1" to="M3"</link> <link from="M2" to="M4"</link> <link from="M3" to="M4"</link> etc. The edges are sparse, so there won't be many of them. I will parse this XML and store this information in an SQL DB, one table for nodes and another for edges. Now, I need to dynamically create strings of the form M1.exe --output_topic=T1 M2.exe --output_topic=T2 M3.exe --input_topic=T1 --output_topic=T3 M4.exe --input_topic=T2 --input_topic=T3 where the tags are sequentially generated. What is the best way to go about querying SQL to obtain these relationships? Are there any tools or other tutorials you can point me to? I've never done graps with SQL. Using SQL is imperative, because we use it for other stuff, too. Thanks!

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  • Serial: write() throttling?

    - by damian
    Hi everyone, I'm working on a project sending serial data to control animation of LED lights, which need to stay in sync with a sound engine. There seems to be a large serial write buffer (OSX (POSIX) + FTDI chipset usb serial device), so without manually restricting the transmission rate, the animation system can get several seconds ahead of the serial transmission. Currently I'm manually restricting the serial write speed to the baudrate (8N1 = 10 bytes serial frame per 8 bytes data, 19200 bps serial - 1920 bytes per second max), but I am having a problem with the sound drifting out of sync over time - it starts fine, but after 10 minutes there's a noticeable (100ms+) lag between the sound and the lights. This is the code that's restricting the serial write speed (called once per animation frame, 'elapsed' is the duration of the current frame, 'baudrate' is the bps (19200)): void BufferedSerial::update( float elapsed ) { baud_timer += elapsed; if ( bytes_written > 1024 ) { // maintain baudrate float time_should_have_taken = (float(bytes_written)*10)/float(baudrate); float time_actually_took = baud_timer; // sleep if we have > 20ms lag between serial transmit and our write calls if ( time_should_have_taken-time_actually_took > 0.02f ) { float sleep_time = time_should_have_taken - time_actually_took; int sleep_time_us = sleep_time*1000.0f*1000.0f; //printf("BufferedSerial::update sleeping %i ms\n", sleep_time_us/1000 ); delayUs( sleep_time_us ); // subtract 128 bytes bytes_written -= 128; // subtract the time it should have taken to write 128 bytes baud_timer -= (float(128)*10)/float(baudrate); } } } Clearly there's something wrong, somewhere. A much better approach would be to be able to determine the number of bytes currently in the transmit queue, and try and keep that below a fixed threshold. Any advice appreciated.

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  • Project Euler Problem #11

    - by SoulBeaver
    Source: http://projecteuler.net/index.php?section=problems&id=11 Quick overview: Take a 20x20 grid of numbers and compute the largest product of 4 pairs of numbers in either horizontal, vertical, or diagonal. My current approach is to divide the 20x20 grid up into single rows and single columns and go from there with a much more manageable grid. The code I'm using to divide the rows into rows is void fillRows ( string::const_iterator& fieldIter, list<int>& rowElements, vector<list<int>>& rows ) { int count(0); for( ; fieldIter < field.end(); ++fieldIter ) { if(isdigit(field[*fieldIter])) { rowElements.push_back(toInt(field[*fieldIter])); ++count; } if(count == 40) { rows.push_back(rowElements); count = 0; rowElements.clear(); } } } Short explanation: I have the field set as static const std::string field and I am filling a vector with lists of rows. Why a list? Because the queue doesn't have a clear function. Also practice using STL container lists and not ones I write myself. However, this thing isn't working. Oftentimes I see it omitting a character( function toInt parses the const char as int ) and I end up with 18 rows, two rows short of the 20x20 grid. The length of the rows seem good. Rows: 18 RowElements[0]: 40 (instead of pairs I saved each number individually. Will fix that later) What am I doing wrong?

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  • Is JavaEE really portable?

    - by Bozho
    I'm just implementing a JavaEE assignment I was given on an interview. I have some prior experience with EJB, but nothing related to JMS and MDBs. So here's what I find through the numerous examples: application servers bind their topics and queues to different JNDI names - for example topic/queue, jms the activationConfig property is required on JBoss, while in the Sun tutorial it is not. after starting my application, jboss warns me that my topic isn't bound (it isn't actually - I haven't bound it, but I expect it to be bound automatically - in fact, in an example for JBoss 4.0 automatic binding does seem to happen). A suggested solution is to map it in some jboss files or even use jboss-specific annotations. This might be just JBoss, but since it is certified to implement to spec, it appears the spec doesn't specify these these things. And there all the alleged portability vanishes. So I wonder - how come it is claimed that JavaEE is portable and you can take an ear and deploy it on another application server and it magically runs, if such extremely basic things don't appear to be portable at all. P.S. sorry for the rant, but I'm assume I might be doing/getting something wrong, so state your opinions.

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  • CakePHP: Custom Function in bootstrap that uses $ajax->link not working

    - by nekko
    Hello I have two questions: (1) Is it best practice to create global custom functions in the bootstrap file? Is there a better place to store them? (2) I am unable use the following line of code in my custom function located in my bootstrap.php file: $url = $ajax->link ( 'Delete', array ('controller' => 'events', 'action' => 'delete', 22 ), array ('update' => 'event' ), 'Do you want to delete this event?' ); echo $url; I receive the following error: Notice (8): Undefined variable: ajax [APP\config\bootstrap.php, line 271] Code } function testAjax () { $url = $ajax->link ( 'Delete', array ('controller' => 'events', 'action' => 'delete', 22 ), array ('update' => 'event' ), 'Do you want to delete this event?' ); testAjax - APP\config\bootstrap.php, line 271 include - APP\views\event\queue.ctp, line 19 View::_render() - CORE\cake\libs\view\view.php, line 649 View::render() - CORE\cake\libs\view\view.php, line 372 Controller::render() - CORE\cake\libs\controller\controller.php, line 766 Dispatcher::_invoke() - CORE\cake\dispatcher.php, line 211 Dispatcher::dispatch() - CORE\cake\dispatcher.php, line 181 [main] - APP\webroot\index.php, line 91 However it works as intended if I place that same code in my view: <a onclick=" event.returnValue = false; return false;" id="link1656170149" href="/shout/events/delete/22">Delete</a> Please help :) Thanks in advance!!

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  • Database for Python Twisted

    - by Will
    There's an API for Twisted apps to talk to a database in a scalable way: twisted.enterprise.dbapi The confusing thing is, which database to pick? The database will have a Twisted app that is mostly making inserts and updates and relatively few selects, and then other strictly-read-only clients that are accessing the database directly making selects. (The read-only users are not necessarily selecting the data that the Twisted app is inserting; its not as though the database is being used as a message-queue) My understanding - which I'd like corrected/adviced - is that: Postgres is a great DB, but all the Python bindings - and there is a confusing maze of them - are abandonware There is psycopg2, but that makes a lot of noise about doing its own connection-pooling and things; does this co-exist gracefully/usefully/transparently with the Twisted async database connection pooling and such? SQLLite is a great database for little things but if used in a multi-user way it does whole-database locking, so performance would suck in the usage pattern I envisage MySQL - after the Oracle takeover, who'd want to adopt it now or adopt a fork? Is there anything else out there?

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  • libav/ffmpeg: avcodec_decode_video2() returns -1 when separating demultiplexing and decoding

    - by unbekannt
    I'm using libav (from a C++ program on Linux and Windows) to decode video streams from a file, which works fine (decoding various formats like H264 and MPEG2) using avformat_open_input(), av_read_frame() and avcodec_decode_video2(). Now I have to separate demultiplexing and decoding. One class will call avformat_open_input() and av_read_frame() and then pass the AVPackets into a queue that is read by another class. There I use avcodec_alloc_context3() to get the AVCodecContext needed for avcodec_decode_video2(). I've tested that with a MPEG2 video stream and it works. Problems arise if I try to decode a H264 stream: avcodec_decode_video2() always returns -1 and outputs "no frame". I understand that additional data (SPS/PPS) is needed to decode this stream, so I've tried to replicate the original AVCodecContext from the demultiplexer in the decoder, but it won't work: Copying the content of the extradata field and setting all other values that differ from the default ones in the decoder: -1 is returned Using the same context (i.e. passing along the pointer) results in a crash I also tried to set CODEC_FLAG2_CHUNKS. avcodec_decode_video2() then always returns packet.size - 3 (??) and frameFinished is never set to 1. In my opinion I have a general problem here that will arise whenever settings from the original CodecContext are needed to decode the AVPackets. I'd be grateful for any hints on how to solve that problem!

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  • Distributed Message Ordering

    - by sbanwart
    I have an architectural question on handling message ordering. For purposes of this question, the transport is irrelevant, so I'm not going to specify one. Say we have three systems, a website, a CRM and an ERP. For this example, the ERP will be the "master" system in terms of data ownership. The website and the CRM can both send a new customer message to the ERP system. The ERP system then adds a customer and publishes the customer with the newly assigned account number so that the website and CRM can add the account number to their local customer records. This is a pretty straight forward process. Next we move on to placing orders. The account number is required in order for the CRM or website to place an order with the ERP system. However the CRM will permit the user to place an order even if the customer lacks an account number. (For this example assume we can't modify the CRM behavior) This creates the possibility that a user could create a new customer, and place an order before the account number gets updated in the CRM. What is the best way to handle this scenario? Would it be best to send the order message sans account number and let it go to an error queue? Would it be better to have the CRM endpoint hold the message and wait until the account number is updated in the CRM? Maybe something completely different that I haven't thought of? Thanks in advance for any help.

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  • bad_alloc occuring when allocating small structs

    - by SalamiArmi
    A bad_alloc has started showing up in some code which looks perfectly valid to me and has worked very well in the past. The bad alloc only occurs once every 50-3000 iterations of the code, which is also confusing. The code itself is from a singly linked list, simply adding a new element to the queue: template<typename T> struct container { inline container() : next(0) {} container *next; T data; }; void push(const T &data) { container<T> *newQueueMember = new container<T>; //... unrelated to crash } Where T is: struct test { int m[256]; }; Changing the size of the array allocated array to anything but very small values (1-8 ints) still results in a bad_alloc occasionally. A few extra notes about my program: - I used Poco::ThreadPool to thread my program. I've only recently added this functionality, before I had it running with Win32 threads. However, only the main thread ever calls push(). - I am also occasionally getting other crashes which could be related. However, when I try to debug with visual studio 2008, I can't navigate back to the call stack, or the crash happens deep within new(). Thanks in advance.

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  • How to use an Audio Unit on the iPhone

    - by CodeToaster
    I'm looking for a way to change the pitch of recorded audio as it is saved to disk, or played back (in real time). I understand Audio Units can be used for this. The iPhone offers limited support for Audio Units (for example it's not possible to create/use custom audio units, as far as I can tell), but several out-of-the-box audio units are available, one of which is AUPitch. How exactly would I use an audio unit (specifically AUPitch)? Do you hook it into an audio queue somehow? Is it possible to chain audio units together (for example, to simultaneously add an echo effect and a change in pitch)? EDIT: After inspecting the iPhone SDK headers (I think AudioUnit.h, I'm not in front of a Mac at the moment), I noticed that AUPitch is commented out. So it doesn't look like AUPitch is available on the iPhone after all. weep weep Apple seems to have better organized their iPhone SDK documentation at developer.apple.com of late - now its more difficult to find references to AUPitch, etc. That said, I'm still interested in quality answers on using Audio Units (in general) on the iPhone.

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  • What techniques can be used to detect so called "black holes" (a spider trap) when creating a web crawler?

    - by Tom
    When creating a web crawler, you have to design somekind of system that gathers links and add them to a queue. Some, if not most, of these links will be dynamic, which appear to be different, but do not add any value as they are specifically created to fool crawlers. An example: We tell our crawler to crawl the domain evil.com by entering an initial lookup URL. Lets assume we let it crawl the front page initially, evil.com/index The returned HTML will contain several "unique" links: evil.com/somePageOne evil.com/somePageTwo evil.com/somePageThree The crawler will add these to the buffer of uncrawled URLs. When somePageOne is being crawled, the crawler receives more URLs: evil.com/someSubPageOne evil.com/someSubPageTwo These appear to be unique, and so they are. They are unique in the sense that the returned content is different from previous pages and that the URL is new to the crawler, however it appears that this is only because the developer has made a "loop trap" or "black hole". The crawler will add this new sub page, and the sub page will have another sub page, which will also be added. This process can go on infinitely. The content of each page is unique, but totally useless (it is randomly generated text, or text pulled from a random source). Our crawler will keep finding new pages, which we actually are not interested in. These loop traps are very difficult to find, and if your crawler does not have anything to prevent them in place, it will get stuck on a certain domain for infinity. My question is, what techniques can be used to detect so called black holes? One of the most common answers I have heard is the introduction of a limit on the amount of pages to be crawled. However, I cannot see how this can be a reliable technique when you do not know what kind of site is to be crawled. A legit site, like Wikipedia, can have hundreds of thousands of pages. Such limit could return a false positive for these kind of sites. Any feedback is appreciated. Thanks.

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