My question is exactly the same as this one, except that... is it possible to achieve the goal with LibVLC? Thanks!
By the way, are there any full-fledged tutorials or books for LibVLC? There are plenty modules mentioned in this page, but without a tutorial it's difficult/impossible for me to understand how they work. So far, the only tutorial I found is https://wiki.videolan.org/LibVLC_Tutorial/ which is very primitive and says nothing about demuxing, decoding, encoding or muxing. Any information or suggestion is highly appreciated!
Related
I've had this question for a while now, but have not been able to find an answer. Any hints or references for further reading would be greatly appreciated.
They are likely to incorporate a library into their own code. If I were writing a browser, I would not count on there being a pre-existing library to do JPEG decoder that would be usable.
I have an alphabet which has not been tackled before, so when scanned, there's no way to detect the letters for recognition with OCR. I'm trying to program OCR for it, but don't have much experience in this. I'd appreciate some hints as to where to get started, and how such a system is normally implemented.
Take a look at this page--it describes the training process for an open source OCR engine.
The free Stanford Online Machine Learning class has a great set of lessons on Photo OCR in Part XVIII.
This blog post has a brief description of the example taught in the class.
There are some excellent resources at google books. Likewise, if you search for Optical Character Recognition on Amazon, there are some pretty up-to-date books that look to be fairly thick and intellectually challenging :D heh
btw - I'm well aware this post has some age, but you never know when some other person might stumble across this and find just what they need. And if this even has the chance of helping out, then so be it. OCR is such a strange subject, that there's not too much out there that can really really answer the deep-machine ended questions. Especially if you're going to attempt to write your own library. :P
Are there any good libraries that can help convert an MP3 into an image of its wavelengths (I think that's the proper term). What I'm looking for is a way to generate the wavelengths of MP3s server-side like is done on Souncloud: http://soundcloud.com/smixx/takin-vc-money-money-cash-ipos
What would be the best approach to extact that type of image from an audio file?
This would be the best response from the community:
http://andrewfreiday.com/2010/04/29/generating-mp3-waveforms-with-php/
The correct term is WAVEFORM that's what you see #soundcloud.
From what I've seen, the PHP script is pretty lightweight and awesome!
BTW: I just realized that the stackoverflow question points to the same PHP code #andrewfreiday
EDIT: Just a FYI, I started playing with node.js for a while now and while I was making a simple MP3 player I started using this packaged for the waveform.
https://www.npmjs.com/package/waveform-data
I am trying to make an application for listening to podcasts. Each podcast is an mp3 file, around 50MB in size. After reviewing the Using Audio chapter of the Multimedia Programming Guide, I decided to use AVPlayer, as the other options did not seem appropriate. However, the more I work with AVFoundation, the more complicated it seems and I have a feeling that simply streaming an mp3 file should be easier. Plus on the top of this document, there is a note stating:
Important: This document contains
information that used to be in iOS
Application Programming Guide. The
information in this document has not
been updated specifically for iOS 4.0
Does that mean that I have some other options, or that AVFoundation is maybe an overkill for what I need to do? I would really appreciate it if someone could clear things out a bit and let me know if I'm making something wrong here.
Thanks in advance!
You should explore Cocos Denshion.
http://www.cocos2d-iphone.org/wiki/doku.php/cocosdenshion:cookbook
The audio engine comes with cocos2d, and it is just 5 classes you can include with your project.
It's very simple to use, as you can see from the above link. It's basically just a wrapper for some AVFoundation classes.
The only trick will be to stream your mp3, but it looks like you can simply update the Cocos Denshion CDAudioManager to hand a URL to the AVAudioPlayer, as a start. Whether or not that satisfies your streaming requirement, I don't know.
At the very least, it will give you some AVFoundation code to study.
I just found a pdf with a nice overview of some possible options from this course blog. Together with Julian's suggestion this is all I could find so far.
I've tried looking up how I might go about this for a while now, and maybe I am using the wrong terminology in my searches or it's way too advanced for me. I basically want to be able to analyze audio files in real-time. I know hardly anything about audio processing so I should probably start small and work my way up. Eventually I'd like to be able to display a power (or frequency?) spectrum correlating to audio playing in real time. Basically like the WinAmp spectogram (terminology?)
Any online tutorials with perhaps an API suggestion or two would be greatly appreciated. I've found some vague explanations (mostly dealing with calculating FFT's then converting them to something...) Like I said, I know little of audio processing, so knowing where to start would be great.
Language of choice: C++
You could look into VST plugins as a starting point for the theory behind audio processing. There's a blog with some tutorials in c++ here.
You can also check out other SO questions on VST plugins for more info.
I believe audacity can run VST plugins, I'll look at that.
EDIT: Audacity doesn't support them out of the box, but you can enable it. You could download a trial of something like ableton live too.
I'd recommend using a graphical tool to begin with to prototype some ideas. Try Puredata or something similar.
http://puredata.info/
Juce is a fantastic way to get to grips with C++ with an Audio slant.
http://www.rawmaterialsoftware.com/juce.php
I've also stumbled across UGen which might help you get up and running without having to understand too much of the sample-by-sample processing theory. I've not looked at this much yet but it looks interesting at the outset.
http://code.google.com/p/ugen/
The KVR forums are full of knowledgable people who will help and direct newcomers to audio and plugin development.
http://www.kvraudio.com/
If you're feeling brave the dive in to a good book. I've heard a lot of good things about the following:
http://www.amazon.com/DAFX-Digital-Udo-246-lzer/dp/0471490784
Good luck! This is not an easy area to get going in!
(PS, the blog linked in the above answer is mine -> it's out of date and wont help you actually do any signal processing)