I'm not talking about any concrete language here. I want to analyse the MP3 file, so I want to get some information about sound from specific second (i don't know, tone/height/frequency of sound). How those data is stored in single file?
Unless you have weeks (months?) available to play with it, I would recommend using an existing MP3 decoding library to pull the decoded audio out of the file. In C/C++, there's libMAD or libmpg123, as well as the Windows components. In C#, you can use NAudio or NLayer.
Once you have the decoded data, you'll need to run a FFT, DFT, or DCT over it to convert to frequency & amplitude. The FFT is probably your best bet, though the DFT may give a less "noisy" analysis. YMMV.
Note that all three of the transforms provide amplitude values you can convert to decibel values.
there are some useful MP3 Librarys where you get information about your MP3 file.
If you use C# it could be NAudio.
http://naudio.codeplex.com/
I recommend the program xxd and google for the first steps.
First of all i would look into its binary code.
xxd -b file.mp3
Viewing it as ASCII also exposes some information.
xxd file.mp3
That was my first steps.
Related
The Kinect OpenNI library uses a custom video file format to store videos that contain rgb+d information. These videos have the extension *.oni. I am unable to find any information or documentation whatsoever on the ONI video format.
I'm looking for a way to convert a conventional rgb video to a *.oni video. The depth channel can be left blank (ie zeroed out). For example purposes, I have a MPEG-4 encoded .mov file with audio and video channels.
There are no restrictions on how this conversion must be made, I just need to convert it somehow! Ie, imagemagick, ffmpeg, mencoder are all ok, as is custom conversion code in C/C++ etc.
So far, all I can find is one C++ conversion utility in the OpenNI sources. From the looks of it, I this converts from one *.oni file to another though. I've also managed to find a C++ script by a phd student that converts images from a academic database into a *.oni file. Unfortunately the code is in spanish, not one of my native languages.
Any help or pointers much appreciated!
EDIT: As my usecase is a little odd, some explanation may be in order. The OpenNI Drivers (in my case I'm using the excellent Kinect for Matlab library) allow you to specify a *.oni file when creating the Kinect context. This allows you to emulate having a real Kinect attached that is receiving video data - useful when you're testing / developing code (you don't need to have the Kinect attached to do this). In my particular case, we will be using a Kinect in the production environment (process control in a factory environment), but during development all I have is a video file :) Hence wanting to convert to a *.oni file. We aren't using the Depth channel at the moment, hence not caring about it.
I don't have a complete answer for you, but take a look at the NiRecordRaw and NiRecordSynthetic examples in OpenNI/Samples. They demonstrate how to create an ONI with arbitrary or modified data. See how MockDepthGenerator is used in NiRecordSynthetic -- in your case you will need MockImageGenerator.
For more details you may want to ask in the openni-dev google group.
Did you look into this command and its associated documentation
NiConvertXToONI --
NiConvertXToONI opens any recording, takes every node within it, and records it to a new ONI recording. It receives both the input file and the output file from the command line.
My line of work requires the use of DICOM files. Each DICOM file constitutes many .dcm files in a single directory. I am required to send these files over the network, a process which is somewhat so due to the massive size of the files.
I am also a programmer and I was wondering what is the ideal way to compress such files? I'm talking about a compression that will be made on the local computer and later decompressed on the destination computer (namely the compression is solely for speeding up the over-the-network transfer of the file). Is there a simple way to crop the DICOM files? (the files contain imaging of an entire head, whereas I'm only interested in a small part of the head).
Thanks!
In medical context, lossy compression is somewhere between not encouraged and forbidden. If you'd insist on cropping existing datasets the standard demands you to form at least new image & series UIDs. The standard does allow losless compression in the form of jpeg2000, but it is quite rare - if I had to bet I'd say your dataset is uncompressed altogether.
In my experience it is significantly better to compress a medical dataset as a solid archive - that is, unify all the images into a single stream. This makes a lot of sense, as there is typically a lot of similarity between nearby images and this is the way to take advantage of that similarity (a unified compression dictionary). This is available as a command line option both to rar and gzip compressors.
Solution:
gdcmconv --jpeg uncompressed.dcm compressed.dcm
or for better compression ratio:
gdcmconv --jpegls uncompressed.dcm compressed.dcm
See:
http://gdcm.sourceforge.net/html/gdcmconv.html
I would also recommend against lossy compression, you would need to be a DICOM wizard to do it properly (see derivation mechanism in the DICOM standard). I would also recommend against cropping the image (you would need to regenerate UIDs, get the Frame or Reference updated...)
HTH
You could use something simple like lzma compression on one end to pack up the files and send them over. This is the easiest solution, since you can grab something like gzip and pack/unpack the files easily programmaticly. This may help considerably, because modern computers prefer transmitting/receiving one large file over many small files (a single 1GB file will transfer much faster than 10000 100KB files).
As for actually reducing the aggregate size, each .dcm file is probably a slice (if you're looking at something like MRI or CT data), and the viewer you are using reconstructs the slices into the 3d image. Cropping them isn't impossible, but parsing the DICOM format is a bit tricky. I'm not aware of any free programs that will help you parse the DICOM files, but I haven't looked for some time.
Since DICOM is a container format, the image data you are after is usually stored in a common format (such as JPEG), so if you are able to grab the relevant part of the file to extract the image data, you can use any of the loads of image processing tools available to crop the image to whatever dimensions you choose.
We have a compression router called "DICOM Shrinkinator" that can do this as it transmits the study to PACS:
http://fluxinc.ca/medical/dicom-shrinkinator/
How to write mp3 frames (not full mp3 files with ID3 etc) from PCM data?
I have something like PCM data (for ex 100mb) I want to create an array of mp3 frames from that data. How to perform such operation? (for ex with lame or any other opensource encoder)
What do I need:
Open Source Libs for encoding.
Tutorials and blog articles on How to do it, about etc.
You should be able to use LAME. It has a -t command line switch that turns off the INFO header in the output (otherwise present in frame 0). If that still leaves too much bookkeeping data, you should be able to write a separate tool to strip that away.
You are already on the right track: use LAME external executable, or any other shell-invoked encoder.
To build MP frames, were your layer of interest is 3, is not easy to do from scratch. There are compression steps, Fast-fourier transforms followed by quantization, which are of complex and tediously long explanation. The amount of work required for a developer to build it from scratch is very big.
There are programmatic C and C++ MP encoding libs, but you will be either asked for fees, be left with very limited support, or have very limited interfacing options.
Go LAME, study their wiki.
How do you programmatically compress a WAV file to another format (PCM, 11,025 KHz sampling rate, etc.)?
I'd look into audacity... I'm pretty sure they don't have a command line utility that can do it, but they may have a library...
Update:
It looks like they use libsndfile, which is released under the LGPL. I for one, would probably just try using that.
Use sox (Sound eXchange : universal sound sample translator) in Linux:
SoX is a command line program that can convert most popular audio files to most other popular audio file formats. It can optionally
change the audio sample data type and apply one or more sound effects to the file during this translation.
If you mean how do you compress the PCM data to a different audio format then there are a variety of libraries you can use to do this, depending on the platform(s) that you want to support. If you just want to change the sample rate of the PCM data then you need a sample rate conversion algorithm instead, which is a completely different problem. Can you be more specific in your requirements?
You're asking about resampling, and more specifically downsampling, not compression. While both processes are lossy (meaning that you will suffer loss of information), downsampling works on raw samples instead of in the frequency domain.
If you are interested in doing compression, then you should look into lame or OGG vorbis libraries; you are no doubt familiar with MP3 and OGG technology, though I have a feeling from your question that you are interested in getting back a PCM file with a lower sampling rate.
In that case, you need a resampling library, of which there are a few possibilites. The most widely known is libsamplerate, which I honestly would not recommend due to quality issues not only within the generated audio files, but also of the stability of the code used in the library itself. The other non-commercial possibility is sox, as a few others have mentioned. Depending on the nature of your program, you can either exec sox as a separate process, or you can call it from your own code by using it as a library. I personally have not tried this approach, but I'm working on a product now where we use sox (for upsampling, actually), and we're quite happy with the results.
The other option is to write your own sample rate conversion library, which can be a significant undertaking, but, if you only are interested in converting with an integer factor (ie, from 44.1kHz to 22kHz, or from 44.1kHz to 11kHz), then it is actually very easy, since you only need to strip out every Nth sample.
In Windows, you can make use of the Audio Compression Manager to convert between files (the acm... functions). You will also need a working knowledge of the WAVEFORMAT structure, and WAV file formats. Unfortunately, to write all this yourself will take some time, which is why it may be a good idea to investigate some of the open source options suggested by others.
I have written a my own open source .NET audio library called NAudio that can convert WAV files from one format to another, making use of the ACM codecs that are installed on your machine. I know you have tagged this question with C++, but if .NET is acceptable then this may save you some time. Have a look at the NAudioDemo project for an example of converting files.
I want to decode JPEG files and obtain uncompressed decoded output in BMP/RGB format.I am using GNU/Linux, and C/C++.
I had a look at libjpeg, but there seemed not to be any good documentation available.
So my questions are:
Where is documentation on libjpeg?
Can you suggest other C-based jpeg-decompression libraries?
The documentation for libjpeg comes with the source-code. Since you haven't found it yet:
Download the source-code archive and open the file libjpeg.doc. It's a plain ASCII file, not a word document, so better open it in notepad or another ASCII editor.
There are some other .doc files as well. Most of them aren't that interesting though.
Unfortunately I cannot recommend any other library besides libjpeg. I tried a couple of alternatives, but Libjpeg always won. Is pretty easy to work with once you have the basics done. Also it's the most complete and most stable jpeg library out there.
MagickWand is the C API for ImageMagick:
http://imagemagick.org/script/magick-wand.php
I have not used it, but the documentation looks quite extensive.
You should check out Qt's QImage. It has a pretty easy interface that makes this task really easy. Setup is pretty simple for every platform.
If Qt is overkill, you can try Magick++ http://www.imagemagick.org/Magick++/. It supports similar operations and is also well suited for that sort of task. The last time I used it, I struggled a bit with dependencies for it on Windows, but don't recall much trouble on Linux.
For Magick++'s Image class, the function you probably want is getConstPixels.
I have code that you can copy ( or just use as a reference ) for loading a jpeg image using the libjpeg library.
You can browse the code here: http://code.google.com/p/kgui/source/browse/trunk/kguiimage.cpp
Just look for the function LoadJPGImage.
The code is setup to handle c++ binding of my DataHandle class to it for loading the image, that way the image can be a file or data already in memory or whatever.
A slightly out of the box solution is to acquire a copy of the netpbm tools, which transform images from pretty much any format to any other format via one of several very simple intermediate formats. They work well from the shell, and are most often used in pipes to read some arbitrary image, perform an operation on it, and write it out to some other format.
The pbm formats can be as simple as a plain ASCII header followed by the RGB data in ASCII or binary. They are intended to be simple enough to use without required a library to implement.
JPEG is supported in netpbm by read and write filters that are implemented on top of libjpeg.