I want to be able to combine multiple tracks of audio into one file but have no idea what to do. I need to be able to do the following:
I need to have multiple tracks playing simultaneously, and need to be alter the volume of each track at various points,
I need some tracks to start at different time,
And I need to be able to write the result to file.
I'm not sure what library to use for this, if anyone has a suggestion that would be helpful.
Nobody has answered this question, so I'll post what I ended up doing. I tried using libffmpeg first, but it was far too confusing to get to work. So instead I used libsndfile which is available under the LGPL. It's extremely simple, but that means there's nothing messy to fool around with. The only problem is that it can't use the MP3 format, so I'll just programmatically call ffmpeg.exe and convert MP3 files to FLAC and load those. It's not perfect but it will do.
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I'm interested in creating a drm type program. I want to put code into an mp3 file that checks online to see if it is licensed out. The online aspect is not something I'm concerned with at the moment, but I've looked online for some resource on doing this, but I've found nothing really that useful. There are people talking about viruses, but I want this to be intentional and not malicious. Simply when you play the the mp3 it quickly checks online to see if the license is actually allowed to play. If it is it plays if it isn't it gives an error and says either you need to log on or buy the song.
I'm pretty sure this is impossible. mp3 files can't contain executable code. They could contain byte data that could represent code, but the mp3 player would need to interpret it as such and execute it instead of trying to play it as music, which no player does. You would have to program your own player to do this, but since there's no way to constrain an mp3 file to only one player (again, because they can't contain code), you'd have to create your own competing standard. Further, there would be nothing preventing someone from converting this mp3 to a normal non-constrained mp3 and sharing it.
From a less technical standpoint, as a user (who despises DRM) it would irk me to no end if an mp3 was checking up on whether I was "allowed" to have it, and even more so if I was required to be online in order to listen to it, to the point that I would just delete it and never buy/download/steal anything in that format again.
(Does this count as an answer? It was too long for a comment.)
Its surely possible but very difficult. Im not very experienced in coding but using discord i was able to turn an mp3 file into a txt file, But the problem is that it becomes strange characters
I am currently creating a game. My game will use music from an mp3 file that the user sends in in order to make decisions on where to place things, how fast the level moves, etc. I am fairly new at this, I have been reading information about mp3. Currently I have found all the frames in the mp3 file that I am using. I don't really know where to go from here. What I want to do is measure the frequencies of the sound wave of the music at certain times (like every sec) and then based on that frequency, do what I need to for the game. I don't know whether I should decode the mp3, that looks like a lot of work and I don't want to do that if I don't have 2 or if I can just read the bytes in the frame and convert them without decoding anything. I am developing this in c#, using the game engine FlatRedBall. I am not using any libraries. I am also planning on selling this game so I would like to avoid using other people's code if I can avoid it. Please someone help me, I just need a direction to go from here. I know how to parse the header and calculate the framelength, I just don't know the next step in what I want to do...
Convert your music to .ogg format which is free and use free library to play it.
Note: I was going to post this as a comment but it quickly grew too big. :)
Writing your own MP3 enconder/decoder is probably going to take a good ammount of effort; effort which would probably be better spent on your game itself. Therefore, is possible, I would be all means try to use an open source library.
That said, most good MP3 libraries are LGPL/GPL licensed. This means you can use it in a commercial setting, as long as you dynamically link to it. Also the SDL Mixer library, as of version 1.2.12, supports MP3s and is under a more permissive zlib license, but since you mention C# I don't know if stable and up-to-date bindings are available. Also since your project isn't written in SDL to begin with, it might be hard to integrate it.
Also, as #pro_metedor hinted, perhaps using a more open format could help in licensing issues. In general, OGG achieves better compression than MP3, which is a plus for things like download size, bandwidth/resource usage, etc.
Just shop around for a while, and try to be a little flexible. I'm sure you'll find something nice! :)
Not sure where else to ask this, so I figured I'd give good old stackoverflow a shot.
Let's say, by chance, I would like to write a library or set of libraries that will create PDF's and convert files to PDF, AND I could care less about how long it will take me to complete (3 months - 10 years.. whatever). I have absolutely no interest in paying for a toolkit... the point of this would be to learn how to manipulate and create files like PDF's. There's nothing business critical about the project, I just want to learn how to do it. Where do I start? I would imagine something like this would be written in C++, but I'm not sure... maybe high level languages would work as well. I'm not looking for someone to tell me exactly how to do it, but send me in the write direction, or at least point out the concepts I would need to concretely grasp before proceeding with such a project.
Any advice and help in directing me here is greatly appreciated : )
Well, you will need a very good understanding of the PDF file format. Adobe publishes the standard and you can start at their site. You can start with the base 1.7 standard and then read the cumulative supplements from there. It is a daunting task, but it can be done and you can pretty much use any language you want, because in the end you are just generating bytes that can be saved to a file.
If you want to convert from, let's say, word documents, it will get a little trickier. Microsoft has published their file formats, which you would have to learn and then learn how to translate that into the corresponding PDF formatting. Also note that the .doc and .docx formats are completely separate file formats and would require separate engines to convert them.
With unlimited time, it is definitely doable, you would just need to ask yourself if it is worth it.
I need to find a video filter in order to mix multiple video streams (let's say, maximum 4).
I've found a video mixer filter from MediaLooks and is ok, but the problem is that i'm trying to use it in a school project (for the entire semester) and so the 30 days trial is kind of unacceptable.
So my question to you is that: are you aware of a free direct show filter that could help. If this is not working then it means i must write one. The problem here is that i don't know from where to start.
If you need output to the display, you can use the VMR. If you need output to file, then I think you will need to write something. The standard solution to this is to write an allocator/presenter plugin for the VMR that allows you to get back the mixed video and then save it somewhere. This is more efficient that a fully software-only mixer filter.
G
I finally ended up by implementing my own filter.
The VideoMixerRender9 (and 7) will do the trick for you. You can set the opacity and area each video going into the VMR9. I suggest playing with it from within graphedit.
I would also like to suggest skipping that all together. If you use WPF, you will get far more media capabilities, much easier.
If you want low level DirectShow support, you can try my project, WPF Mediakit. I have a control called MediaUriElement that is similar to WPF's MediaElement.
This question has been in my mind for a few years and I never actually found the answer for this.
What I would like to do is extract the actual waveform/PCM of an MP3 file, so that I can play it using the soundcard (of course).
Ideally I would be experimenting some DSP effects.
My first step was to look into LAME, but I didn't find anything relevant about MP3 decoding in a program or stuff like that.
So I'm asking where I could find something like this.
What language should I use? I was thinking C, but maybe there are programming languages out there that would do the job more efficiently.
Thanks!
Guillaume.
The question boils down to: what are you trying to accomplish?
From the description of your question of decoding an MP3 and playing it on the sound card makes it sounds as if you are trying to make a media player.
However, if your intent is to play around with DSP effects, then it sounds like the question is more about processing the sound rather than decoding MP3s. if that's the case, probably looking into writing plug-ins for existing media players (such as Windows Media Player and Winamp) would be easiest path to what you're trying to accomplish.
Frankly, learning to write your own decoder from scratch is not just a programming problem but a mathematical one, so using existing libraries are the way to go. Talking to the operating system or libraries like DirectSound to output audio seems like unnecessary work if anything. I feel that working on plug-ins for existing players would be the way to go, unless your goal is to make your own media player.
If what you really want to accomplish is playing with audio data, then probably decoding an MP3 to uncompressed PCM using any MP3 decoder, then manipulating it in the language of your choice would accomplish your goal of dealing with effects with sound.
The language choice is going to depend on whether you are going to interact directly with MP3 decoding libraries, or whether you can just use raw audio input, which would allow you to use pretty much any language of your choice.
There was a similar question a while back, Getting started with programmatic audio, where I posted an answer on some basic ways to manipulate audio, such as amplification, changing playback speed, and doing some work with FFT.
libmpg123 should do the trick.
I have been using the Windows Media SDK, not for this purpose, but I am pretty sure there are hooks let that let you intercept the audio stream, or convert MP4 to uncompressed WAV. I used C++.
Lots:
http://www.mp3-tech.org/programmer/decoding.html
Pick your poison...
Also, LAME does decode MP3s (check out --decode option), so you might find something interesting in that source.
-Adam
It really depends what platform you are programming on and what you want to do with the code. If you are on Windows you should look at the windows media format sdk or DirectShow. They should both have the ability to decode mp3 files into the raw waveform. On the Mac, I would expect Quicktime to have this same ability. Others have already suggested source for Linux/open source code.
I would recommend looking at Cubase and Wavelab as both will convert MP3 to WAV etc and allow you to play around with the waveform