Hi, it is possible to do this using both methods:, but it is easier using ffmpeg. I would recommend you Google ffmpeg and check their examples, you could accomplish your task in about 60 lines of code. Happy coding
Thanks for ur suggestion.I have two AVI files.One is compressed and the other is uncompressed.I want to extract the frames from both the AVI files.Will the FFMPEG library work for both compressed and uncompressed AVI files?
Hi Ashwath, the FFMPEG library will work for both files. As a side note, the library comes with pre built executables which you could use to immediately extract the frames you need, there are tons of articles online about how to do this - just download the library an programs from here and check their online documentation for the parameters you need to extract the frames.
Actually what i am doing is that i have created a MFC dialog based GUI.And i want to extract the frame buffer from the compressed AVI file by decompressing it first and then copying the buffer values to unsigned char array and display on a picture control as a bitmap image.And i want to extract all the files in the compressed AVI file in this way and display one by one on the picture control on the MFC GUI.
You can get an image from the avi stream using ffmpeg, into an av_picture structure, then use the libswscale functions to scale and convert the image into different resolutions or formats, and finally draw the buffer to a control on your mfc gui. You should really Google for code samples.
Normally, the CMainFrame object is constructed in the InitInstance method using the call -
pDocTemplate = new CSingleDocTemplate(
RUNTIME_CLASS(CMainFrame), // main SDI frame window
Do you see this call in InitInstance?
If you don't see this, it means that the construction is being done elsewhere; your app class constructor perhaps.
If you do see the above code and you still have the behavior you mentioned, it could mean that some other CMainFrame instance is being constructed.
Whatever the case, it is not the correct way to do it.
«_Superman_» I love work. It gives me something to do between weekends.
Hi guys, I'm using WinHttp in a regular Win32 app (Windows SDK in C++, no MFC) and I want to prevent automatic redirects. The only thing I could find is WinHttpRequestOption but I have no idea how to set that or if that's what I need to do.
I want my code to check for a redirect before proceeding.
This fix applies to VS2012 MFC projects that use the Windows7 Visual Manager style. It causes active button caption text to draw in color 0,0,0 and not the same color as inactive.
This restores VS2010/2008 Feature Pack behavior.
Hello, I thought to post this to CP in case others had this issue. In 2012 MFC was 'fixed' to draw text using TextNormal as specified in Style.xml resource (I suspect that TextNormal should have been 0,0,0 in 2010 but it went unoticed).
People, I found that CFileDialog class causes serious problem. I had a large free memory block in the address space of my prog: 1200 MB Then I create CFileDialog and delete it: CFileDialog *pdlg=new CFileDialog(TRUE); pdlg->DoModal(); delete pdlg; I check address space again and found only 700 MB: The reason was very simple: I found some dlls in the address space of my process like urlmon.dll, netapi.dll, modemInst.dll and so on. These dlls was loaded into my address space by CFileDialog class and was not unloaded by its destructor. As a result, I couldn't allocate memory for a large file- address space had been fragmented. Any idea how to solve this situation? I think to create CFileDialog in a separate process. May be, there are better variants?
[quote]If you're sure the memory is being taken up by those dlls, why not try unloading them yourself with FreeLibrary()? How are you trying to allocate the memory? Have you tried the VirtualAlloc() function?[/quote]
Yeah, I'm sure because I saw list of modules, downloaded in the address space before creation of CFileDialog and after it had been destructed. I tried to use FreeLibrary for such modules. After it (not immediately) program failed, giving me some inaudible error messages. Yeah, I used VirtualAlloc(). It is the best if you need to allocate large memory block. Currently I created a new process, which works with CFileDialog, leaving my address space untouched. It works, but I think that it is not very elegant approach. And one mysterious dll still presents- modemInst.dll (it is not connected with CFileDialog).
A program using DLLs may delay loading them unto the point when they're first needed. This appears to have happened here. The problem with that is that the DLLs will then stay until you exit your program, or manually unload them (as suggested above).
Why CFileDialog loads all these DLLs isn't clear to me. My guess would be file preview settings - but then I would have thought the DLLs used for previewing would be loaded to system memory, not application memory. Anyway, this is not in fact a memory leak, "only" a shortage of memory.
Moreover, you should normally not even be able to notice memory fragmentation, except for the fact that the operators new and delete notably slow down when you're low on memory. The system memory manager hides the true physical memory addresses from you, and translates them to a virtual application memory address space. So even if you get addresses from allocations that indicate a state of fragmentation, this may be misleading.
That said, the memory manager will easily allocate huge blocks of memory for you even if fragmentation does split up your memory into unusably small chunks: it has the ability to pretend a contiguous block of memory, even if the physical memory is spread out all over the entire available physical memory space.
Your problem is a different one however: you cannot load a large file into memory as a whole. that means your application is using more memory than available. Note that even with 16 GB RAM, the memory space of an application is limited to no more than 4 GBm or in Windows in fact only about 2-3 GB, depending ont the OS version.
The solution is to split it up. It isn't a good idea to load such big files into memory anyway - exactly because of the problem you encountered. Depending on what you wish to do with that file, you don't need the full file at any point in time anyway. Instead use a buffer of at most a few MB in size, load a chunk, process the data, store the intermediary results, then repeat until you're done.
To unload libraries which you did not load is unsafe op- just as Stephen wrote. try delete twice the same object and you'll see what will happen. To perform this op, one has to know how they were loaded and unload them exact in opposite order. Moreover, he must know, that nobody else will try to unload these libraries too. I tried, and program failed. CFileDialog loads all these libraries for the very simple reason. It offers such service: one may open file from remote disk for example (or you may type an URL in address bar). Dear Stefan, you are not right about memory manager. I do not see physical addresses, but only virtual ones. In my virtual address space I have to have a continuous block of free memory in virtual address space to allocate large file (and no matter, what I use- VirtualAlloc, new or MapViewOfFile). I can clearly see fragmentation of my address space, when I run my prog under debugger. As I wrote, I had 1.2 GB continuous block before creation of CFileDialog and only 0.7 GB after it. If I can to download large file, I will do it. To split file is the last chance. Any idea, what headache will I have, if for example I need to rotate large file, which cannot be downloaded in memory?
Yes, unloading is a risk. I've read Stephens comment and therefore omitted that warning. Maybe I should have pointed it out nonetheless.
Regarding fragmentation, maybe I haven't been clear. Indeed, all you see is virtual addresses. That's what I meant when I said the MM hides the true addresses from you. As a consequence, you won't know if the addresses you see point to two blocks of memory that lie next to each other, or if they are sperated by a 5GB gap. In fact, you don't even know if one of those blocks is in fact contiguous - part of it may have been moved to the page file!
In any case, as pointed out before, the state of fragmentation is irrelevant to your problem. Your problem is you're running out of memory.
You only have a few options:
a) reduce memory usage elsewhere; apparently that may not be easy or even work
b) make your application a 64 bit application, enabling it to use a bigger address space; of course this only helps if your total memory is big enough, but you can increase available memory by increasing the page file on your system.
c) split up your file and adapt your program to work on it bit by bit.
Have you ever read what I wrote? My problem is NOT that I'm running out of memory. I had enough of it before I created CFileDialog. I wanted open a file of size 880 MB, having 1.2 GB of free memory memory. But I had not a continuous block of memory after CFileDialog was destructed. One very simple but not elegant way to resolve this situation was to allocate 1.2 GB using VirtualAlloc, then create CFileDialog. It downloads its modules in memory anyway, but large block will remain intact. Memory would not be as fragmented as it was if I previously created CFileDialog. Another way, to which I came up was to create a separate process, create CFileDialog within it and return what I needed (path to file) to the parent process using one of appropriate methods (I used memory mapped file). It is a programming- there are usually many ways to do same thing. I thought about which method is the best. May be, there is a way to get CFileDialog to work more correctly than it really does. I did not dig in its source code. I do have too much problems with algorithms to waste time for such thing. When you are short of resources (few memory, weak processor and so on) it definitely makes you more disciplined. And I have no intention to buy another comp and 64 bit OS - let's my boss do it.
Last Visit: 31-Dec-99 18:00 Last Update: 2-Sep-15 8:17