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And you asked the same question twice. When you already have (at least) two answers (one of them, mine). So why ask another time without checking if your previous question was already answered?
And for the future... Noone here is an employee in forum (but the owners of site), they help because they want it. So BE PATIENT, this is one of the fastest forums I have ever seen, but the people work in other things, eat, sleep, have family and so on...
And there is people of the whole word, so timing can be very different. And when you post, although it is active time for you, is the "quiet" part in forum.
Greetings.
--------
M.D.V.
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
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Can you structurate your message a bit better? I dont understand you correctly, having it difficult to answer you
Greetings.
--------
M.D.V.
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
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I am trying to record a wave file using "winmm.dll" from a web application.
I am able to record that .WAV file in 11025 samplespersec, 16 bit, mono format. But my requirement is to record that in 8000 samplespersec, 16 bit, mono format (wave format). How do I meet my requirement ? Is there any other DLLs or ActiveX control to meet my specifications ?
thank u all....
with regards,
kiran
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Have you got a copy of Goldwave? I'm not sure if it's open source these days but it is the business when it comes to audio formats.
Nothing is exactly what it seems but everything with seems can be unpicked.
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kadkir wrote: But my requirement is to record that in 8000 samplespersec, 16 bit, mono format (wave format).
You can simply change these things in the header that is prepared for recording as well as file writing. Have you look at the code in deep?
- NS -
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I did the same using set command string (passed as param to mcisendstring function). But I am getting "value out of range exception..", what to do with this ?
thank u,
kiran.
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kadkir wrote: I am trying to record a wave file using "winmm.dll"
So you're using the waveIn___() APIs?
If so, you can specify the format you want to record in your
call to waveInOpen() (see the WAVEFORMATEX struct parameter).
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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Hello everyone,
I have a large data set of integers (about several Million), all of them are positive integers from experiment. They are stored on a file on local machine. I want to select the largest 1000 values then make analysis based on the 1000 values.
Could anyone suggest some efficient solutions? I think sorting the several M data in memory is not feasible.
thanks in advance,
George
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use map for initially storing the integers
use this map to write integers to file
Using map will unsure that integers are sorted even when written to file
read first 1000 values from file ....now you will get them as storted
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Hi ccpptrain,
What do you mean map?
regards,
George
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Thanks abhijit,
I think you mean put all several hundred Million data samples into a memory based data structure Map. I think the memory will be used out. 
Do you have any other ideas?
regards,
George
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It is a generalization of your hand-crafted container. There are several C++ classes implementing it, see, for instance:
std::map [^]
and
MFC CMap [^.]
Hope that helps.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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Thanks CPallini,
I have read through the MSDN reference. I think the memory will be used out if I choose to make all data in pure memory based data structure Map. If I have only several hundred or several thousand of data samples to select, it will be ok to use Map. But now I have several Million data samples.
Any ideas to save memory and do not degrade performance too much? (I think using Map could have very good performance if the total memory is enough.)
regards,
George
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George_George wrote: What do you mean map?
learn C++ containers 
but, hey !!!! where's my answer bloody lamer ?
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why map ?
map forbids to have 2 keys identical, and FWI understand, there no need for a pair of (key; value).
vector is good enough then...
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You don't need to sort the values, you have just to pick the 1000 largest ones, hence only a traversal of the whole set is needed.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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Hi CPallini,
I think you mean I use sorted Map right? I have used Map before for small amount of data, e.g. several hundred or something like this. But in current situation, I have several Million data samples and I will have more in the future.
I am afraid that we can not put all the data (such a big volumn) into memory based data structure Map.
Any comments or ideas? I am looking for some other ways which consume less memory (maybe we only store a part of the data set into Map?), and which also does not degrade performance too much.
regards,
George
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is processing time a constraint for you?
means, if the logic takes suficient time, then, is it ok?
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Thanks chandu004,
I want to find a balanced solution between memory footprint and processing time. To tell the truth, the memory can not hold all the data, maybe only 2% of the data. Any ideas?
regards,
George
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here i have an idea. but not sure about the processing time complexities. we have to work them out practically and see.
George_George wrote: memory can not hold all the data
thats true.
but i think that, memory can very well hold 1000 structures of the following type.
struct linkedlist
{
linkedlist * prev;
ULONG value;
linkedlist *next;
};
//the size comes here to be 4*3*1000(max)bytes.
1.define a linked list.
2.take care such that, when ever, any item is added into the linked list, and the count is >1000, delete the last one.
3.now, read each value from the list and insert it just in between the two values, of which, one is greater and the other is smaller.
4.in this case, at any point of time, the largest 1000 values will be handled by the linked list.
i hope, this algorithm is suitable for your application.
or if you fell that, iam wrong, please try to correct me.
thank you.
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Thanks chandu004,
I can understand that your solution could work and does not consumes too much memory. And I want to confirm that you need to sort the linked list by the value element, right?
But I doubt the performance of your algorithm, because I think we could save time to do a sorting (I want to largest 1000 values, and they do not need to be sorted). But I do not have smart ideas about how to optimize the performance of your algorithm. I hope you or other people could provide better ideas to make enhancement.
regards,
George
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George_George wrote: I want to largest 1000 values, and they do not need to be sorted
thats fine, but unless we have the latest 1000 elements sorted, we cannot insert 1001 st element at the appropriate place.
any way, here i could workout a rough algorithm. please go through it.
1.maintain the head and tail of the linked list in some global variables.
2.say we already have some values in the list as
207,30,29,21,......,5.
3.now in this case, we know that, the max element is 207(HEAD) and min element is 5 (TAIL).
4.now, in this case, if we get an element smaller than 5, we can directly discard it because, it is nomore eligible to fit into the top 1000.
5.if we get an element say, 25,
while(linklist->value>element)
linklist=linklist->next;
6.now insert it there, and delete the link to the last element, thereby maintaining the list size to 1000.
7.in general, whenever any element is inserted into the list, then delete the last node and make its previous as the last.
thanks for such an interesting post and if it is possible to send the file(the million values file) then i shall try to implement this algorithm.
otherwise, i shall generate one such file with random numbers and see.
BTW, can you tell me the size of your file in GB or TB
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Thanks chandu004,
The size of data is tens of G.
Your solution should work. Thanks. I am thinking whehter your method could be improved by reading more data into memory? Like, maintain 10000 data in the linked list? Is it better? I do not know whether you have better ways to improve it (I mean performance).
regards,
George
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If anything, I think maintaining 10000 values would be worse, as the average and worst-case insertion times would increase, while I can see no real tangible benefit.
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