Is there a way to find the codec/container of an audio file using Apple APIs (AudioToolbox or Quicktime)?
You can practically read all possible information from a QuickTime movie using its internal movie atoms.
What you need is the "Sample Description Atom" of the sound track.
You can find further information here :
http://developer.apple.com/library/mac/#documentation/QuickTime/QTFF/QTFFChap3/qtff3.html#//apple_ref/doc/uid/TP40000939-CH205-75770
As can be seen, there are certain values defined for many kinds of different audio file formats.
These QT Atoms are a bit tough to understand at first, but this is basically the way to go to retrieve all information necessary.
There is a tool by Apple called the "Atom Inspector" to give you an overview of all atoms a movie contains and their values.
Hope that helps!
Related
Assume I have sensitive information (passwords, private keys,...) that I saved to a file which I encrypted.
Is there an easy to use tool to convert back and forth between a small file (say 0.5kB) and an image (QR code?) that I can print out to have a safe backup?
You can use LaTeX with the ps-tricks and pst-barcode modules, it produces nice QR codes, and yesm we used it exactly for this purpose: Paper backup of SSH private keys.
Denso Wave of QR code developer distributes software on their site.
Membership registration on the site is required to obtain it.
Even if you can not print with this, there are various tools regardless of free/commercial, so please search.
The maximum amount of data that can be stored in the QR code is 2953 bytes in binary mode.
However, it depends on the ability of the scanner to use.
QR code FAQ #6 Can an image or sound be stored in a QR Code?
I wrote a linux program to do this, called qr-backup.
In researching similar programs as part of it, I discovered a number of alternative projects as well. All of these are also linux-only.
asc2qr.sh
paperbackup. Focused on GPG/SSH key backup. See also the paperkey preprocessor, to reduce the size of keys.
qrdump (incomplete)
qrpdf
If your file is very small (0.5KB is a good cutoff), you can generate one single QR code. An example command-line program to generate it is qrencode. Several web converters are also available.
I'm trying to understand how I can generate a waveform from an audio (or video) file to display to the user.
I've been googling around for quite a while now and can't determine if this is even possible in Qt without using something like FFmpeg. I've seen all of these classes: QMediaPlayer, QMediaContent, QMediaResource, QAudioProbe and experimented with the Qt Media Player Example but am just not seeing where I can access the actual audio buffer.
So I have 2 questions:
Is what I want to do even possible without 3rd party libraries?
If it is possible, can some kind soul outline what I need to read and understand in order to access the audio data
I have tried the suggestions from this question (Audio visualization with QMediaPlayer) but the result of audioProbe->setSource(player) is always false and the method processBuffer never gets called.
audioProbe = new QAudioProbe(this);
bool success = audioProbe->setSource(player);
qDebug() << success;
connect(audioProbe, SIGNAL(audioBufferProbed(QAudioBuffer)), this, SLOT(processBuffer(QAudioBuffer)));
Update: Adding some additional detail in the hope of clarifying things.
For testing/learning I am using the Media Player Example which ships with Qt, so it is set up correctly with Q_OBJECT etc.
For audio, I tested with both .mp3 and .wav files. FWIW, the player example won't play video for some reason (.mp4, .avi were tested)
The player in the code is QMediaPlayer – which inherits from QMediaObject. The example code for the Player class is here. I added my code (in original comment above) right after the player is instantiated. I also tried adding it once media is loaded.
I tried declaring my slot first as private, then as public – either way, it is never called.
Frustrating that such a simple thing is so hard.
Going the "no external library" route will likely just lead to more of a headache and more work than is necessary. The other advantage of going with an established library is you won't be bound to one file format, as not all formats store their data the same way. If the audio format is uncompressed (wav or other) you can read the header until you get to the data chunk. An answer to this question here details this in C. You should be able to get an idea for the file format from this to apply it to another language.
You will want to understand how many channels are in the wav file, bit depth, and also the sampling rate before you can do anything worthwhile with the data. All this info can be grabbed from the header.
It turns out that QAudioProbe is not supported on OSX – the platform I am working on. Took quite a while (a "Qt while. . .") to ferret that info out so I am posting it here explicitly.
See this document for full details: Qt 5.5.0 Multimedia Backends
I am new to PACS and I would like to get some clarification about the web-based PACS system. Almost all the articles in internet talks about the Protected Health Information (PHI) that is associated with a DICOM image and recommending to rip off this information before sharing the image to someone else. I would like to understand how it can be done.
I am aware that if we convert the DICOM image into a PNG or JPEG image the DICOM header information will be removed. But, I wonder what if we need the original DICOM image any time and how do we re-create the PHI into a PNG image and get it as a DICOM
I have an apache web server and a MySQL database, both are installed in separate ubuntu servers. I want to know how can I securely share the patient scan/X-ray images via internet.
I really appreciate if someone could explain me in detail and thank you for your time and consideration.
PHI stands for Personal Health Information, not Protected Health Information.
A scan stored in the DICOM format contains many tags, some of which could identify the subject. There are some anonymizer programs you could incorporate in your setup.
Two programs I have tested are:
the CTP program by the RSNA project. (free and open source java)
Neologica's Dicom Anonymizer (free to use trial)
I'd post the link, but need 10 rep to post more than two links
which is completely stupid, but please try it out.
Both have an understandable interface and easy configuration wherein
you can decide which tag content to remove, or what to replace it with.
You should really read up on the tags and possibilities, but to give you an idea:
CTP anonymizer
Neologica's anonymizer
You need to make a distinction in between :
An Anonymization process
A de-identification process
In the case of Anonymization everything is lost for good as you mentionned. In the case of de-identification everything is hidden. This is described specifically within the DICOM Standard E.1 Application Level Confidentiality Profiles.
While there are plenty of non-standard DICOM anonymizer out there (use dd or hexedit in the worse case), there are very few de-identifiers out there. gdcmanon implement a previous DICOM release (before Supp 142 came out) in the command line tool.
You may want to read also: An Open Source Toolkit for Medical Imaging
De-Identification.
And if this still not enough reading, I suggest you also dive into the world of 'Private Attributes' (!= Public attributes), with the particular issue explained here regarding PHI.
We are currently working with the Gracenote Music API and are wondering if there is a full list of generes and mappings between the different hierarchies of genres. Ideally, we'd love a dump of those tables in the backend Gracenote system. If .csv's, text files, or even XML are easier to provide, we will figure out a way to import that data in our system.
If a full mapping isn't available, a list of top level genres would be very helpful.
I'm afraid there is no way to iterate the list of genres via the Web API. Most of the client SDKs have this capability.
It turns out that there are at least three sources for example code in the GNSDK:
Properly maintained samples in the "samples" directory. This will compile into full applications with minimal effort (once you've settled on a makefile solution for your platform, as a complete Automake setup is not yet part of the package).
samples/code_snippets - These are useful to look at, but do not necessarily build into full apps, and may not be completely up to date with the SDK.
Code linked from the documentation. This is a problem if you downloaded the SDK as an archive and the documentation as a PDF, as the links will resolve as relative file links, not HTTP links, and you won't have the files. You need to look at the HTML version of the documentation on the server to find these files. However, they are apparently outdated and will not build without some (relatively minor rework). This can be done using the primary samples as a guide.
So, all of that said, what you want to look at in the GNSDK Developer's Guide is "Advanced Topics : Using Lists". You will want to read that entire section, then find and work with the sample application referenced on page 93.
To get the list of genres (or moods, or eras) you need to make a call to the "fieldvalues" API, you can see how to do it here:
https://developer.gracenote.com/rhythm-api#attribute-station
This call will give you the list of supported genres:
https://cXXXXXXX.web.cddbp.net/webapi/json/1.0/radio/fieldvalues?fieldname=RADIOGENRE&client=CLIENT_ID&user=USER_ID
You can then use the returned ID's with pygn.createRadio()
I´m working on an application based on directshow that has to convert an AVI source file to to an mp4-file that can be played back with Quicktime.
Since 3ivx, according to my web research the most popular way to fulfill this task, has become commercial (and my budget is quite limited), I decided to use a solution based on ffdshow.
I created a simple graph in graphedit, using LAME for audio encoding and GDCL MPEG 4 Multiplexor for the muxing, but everytime I try to play the movie with Quicktime, I´m getting an error indicating a wrong "sample description".
Playback with Windows Media Player is working, except that there is no sound.
My guess is that there´s a problem with the muxer, because every time I try to add audio encoding, graphedit automatically adds an decoder after the encoding unit (see picture link).
http://imageshack.us/photo/my-images/39/graphjrgr.png/
Any ideas on how to integrate ffdshow in a better way, tips for alternative mp4 muxers, or a complete different approach are appreciated!
The GDCL muxer has limited number of audio formats that it supports, probably you should check the source code for the muxer to see if the formats you are using are in fact supported. Basically, you need to choose an audio encoder that the mux recognizes as valid. It might be possible to use GraphEdit to choose different properties for the encoder filter that allow things to work better.
I have had some luck with the Monogram x264(video) and AAC(audio) encoders. See http://blog.monogram.sk/janos/directshow-filters/
Finally, try the debug version of the GDCL mp4 muxer.
Also, you must be aware of MPEG-4 LA licensing requirements for x264 http://www.mpegla.com/main/programs/AVC/Pages/FAQ.aspx