I had been using libsndfile library. But only recently, I found some of my wav files have this extra JUNK section inside and libsndfile is not categorizing it as JUNK but simply reading this as data.
The structure of my wav file is shown here:
.
I want to know how I should be able to SKIP or ignore this JUNK section.
Note that fmt is now at offset (off=56) instead of off=20, which is when my test.wav does not have any JUNK.
If the solution is to use some other library than libsndfile, then please suggest, which one would allow me to programmatically skip this JUNK block.
Related
I am trying to remove the PDF/A markers in a file — I have no access to Adobe Acrobat — as some tools balk at PDF/As. Is there a way to revert a PDF/A to a normal PDF with free software tools? I am running Debian testing.
The indicators for PDF/A are in the Metadata entry, but you do not want to erase that entire entry. Instead you would want to modify it.
To modify, you can extract the XML string, modify using whatever XML tool is handy for you, and then "update".
These three entries are the ones you want to erase.
pdfaid:part
pdfaid:amd
pdfaid:conformance
Of course this still leaves you with the following tasks, with 1 and 3 normally done using a PDF SDK library.
Find and extract the Metadata entry (it could be compressed in the PDF)
Reading and editing the XML (should be trivial)
Updating the Metadata entry with your modified XML
Since you gave no indications of platform+OS I can't advise any further.
So, I decompressed an exe file and modified it, and I want to recompress it back to exe form, not an SFX archive.
I can't find an internet solution for my problem, all of the posts I look at talk about recompressing to an SFX file, which I do not want to do, I want to convert it to a fully working exe.
I think you are looking for IExpress.exe: https://www.maketecheasier.com/create-self-extracting-archives-without-installing-software/
Modifying a binary file without breaking it requires a knowledge of hex or assembly. You can't just decompress and compress it back.
How ever there are tools that has ability to make some minor changes to an exe file. This one is an example. Those tools can only alter exe file's resources like icons, some of the texts, images etc.
Hope this helped.
As far as I can tell my question is not related to topics involved in Stenography or in the win.rar soluations I've seen to this where you are essentially hidding messages.
I am trying to figure out if there is a way to insert code into a file such as a jpg or png with a simple message, that could later be extracted by a program reading the file without having it encoded into the file either by slight differences in pixels or what have you in stenography.
I basically just want a tag along message that is a part of the file itself that is not brought up by the image reader but could perhaps be seen by a text reader of some kind.
I'm not sure how possible this is because I, for the most part don't understand the order/layout of the png/jgp/ect file aside from the RGB pixel code. How does it start, how does the image display tool know to stop displaying ect.
The way I'm envisioning it would be something like:
pngStartCode -> RGBinfo --> png end code so image reader knows to stop -> start sequence that some kind of reader will recognize (possibly a new text reader) -> written text wanted to be communicated -> endcodeforreader
I may just be rambling about something ridiculous here but please let me know if this is at least possible.
You can use following command(Windows command prompt)
Create a text file with your message, say "message.txt"
Now choose target file(it can be any file like a.jpg,a.png,a.exe,..etc), say "image.jpg"
Now execute follwing command
copy /b "image.jpg"+"message.txt" "NewImage.jpg"
Above command will combine files(in binary mode) and creats a new file(in this case NewImage.jpg). Now if anyone opens image they will just see noraml image. If you want to look at text, you have open it with any text editor(Notepad) and scroll down to last, there you can find text.
Here it wont chage any pixels or any thing to image, it just appends text to image.
It sounds like OP is asking about comment tags in the PNG specifications (i.e. adding data but without intent to hide it).
PNG files are broken into "Chunks". The image part is usually divided into several IDAT chunks; the color, size, etc are stored in an IHDR chunk, etc.
The iTXt, tEXt, and zTXt chunks are used for conveying text information associated with the image, so typically you'd look into using a tool to add those types of chunks. tEXt is for just plain text, zTXt is compressed.
More info on the PNG specification including what kinds of chunks are available can be found here, and you find chunk viewers on google.
For convenience at preset time (January 2021) here are a couple tools that will let you view, edit, and add chunks:
Windows 10: http://entropymine.com/jason/tweakpng/
Linux: https://www.systutorials.com/docs/linux/man/n-png/
Mac: https://apps.apple.com/us/app/inspectpng/id498851708?mt=12
NOTE: I do not vouch for the safety of any of the above links. Please use standard caution when downloading any file from the internet. If you don't have your own anti-virus, Virustotal has one online you can upload individual files to for free.
I have a program which writes the output as binary vtk file. Being a binary file, I am not able to understand it. However, I would like to read the contents of the file for my own understanding. Is there a way to view it in ascii format (so that I could understand the data better)?
A hex-editor or dumper will let you view the contents of the file, but it will likely still be unreadable. As a binary file, its contents are meant to be interpreted by your machine / vtk, and will be nonsensical without knowing the vtk format specifications.
Common hex dumpers include xxd, od, or hexdump.
I want to use a algorithm to reduce memory used to save the particular text file.I don't really know how text is stored but i have an idea in mind.
Would it be better to extend a open source text editor (if yes than which one) or write a text editor myself.
It would be nice if someone could also give me a link or tutorial to some basics on how text editors work and the way data is stored.
Edited to add
To clarify, what I wanted to do is instead of saving duplicates of a word make a hash table and store the address where it needs to be placed.
That way I wouldn't be storing the duplicates.
This would have become specific to a particular text editor.
Update
thanks everyone I got what all of you'll are trying to say. Anyways all i wanted to do is instead of saving duplicates of a word make a hash table and store the address where it needs to be placed.
This was i wouldn't be storing the duplicates.
Yes and this would have become specific to a particular text editor. never realized that.
I want to use a algorithm to reduce memory used to save the particular text file
If you did this you would no longer have a text editor, but instead you would have created some sort of binary file editor.
The whole point of the text file format is that it is universal, meaning any text file can be open in any other text editor.
Emacs handles compression transparently. Just create a text file with .gz extension. Emacs will automatically compress contents of the file during save operation, and decompress when you open the file next time.
Text is basically stored as-is. i.e., every character takes up a byte or two (wide chars), and there is no conversion done on it when it's saved. It might add an end-of-file character or something though. Don't try coming up with your own algorithm to compress these files. That's why zip-files and other archives were created. They're really good at compressing text. If you wanted to add these feature to your text-editor, you'd have to add some sort of post-save hook to zip it, and then put a hook on the open command to unzip it. Unless you wanted to do it by hand every time. Don't try writing the text editor yourself from scratch, unless (maybe) you're writing notepad. Text editors with syntax highlighting aren't very easy to make, even with the proper libraries. I'd say write a plugin for something like Visual Studio or what have you. Or find an open-source text editor.