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I want to know about Linux audio, i spent a lot of time on reading but i didn't understand(clearly). Can anybody give a brief information on various Linux audio sub systems(Like OSS, ALSA, JACK, Gstreamer, Phonon, Xine)?.
Any help, Thanks in advance.
I once wrote a famous blog post about the jungle of Linux audio output formats. You can find it here.
Regrettably, the picture is no longer there, here's a copy:
It's a bit old (dating from 2007), but I hope it gives you the general idea. OSS and ALSA are the layers closest to the actual audio hardware. All the other libraries and frameworks simply talk to those lower layers. And as you can see, some of these libs and frameworks actually have wrappers around other libs and frameworks.
Which layer you want to call upon depends largely on what you wish to accomplish.
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I'd like to write some library/app to interact with Galaxy Buds.
I assume that this would require me to somehow sniff packages it sends to my mobile telephone and get which corresponds to what command(volume/pause/play) and so on. And then write some wrapper for it? I'd like to make this app/library reusable between different Linux distros, and not-that-hard-portable to Mac OS.
Knowing all that I still in the place where I'm not sure where to start from.
I'd appreciate suggestions to any part of this process e.g (Programming language selection, software for BT sniffing ...)
I do have some experience with C#/Java/C++, but I'm willing to learn if these aren't most suitable for solving the issue.
I don't know that much about the libraries needed for such a solution, but as far as sniffing is concerned, I know that Wireshark (WireShark_Bluetooth_Sniffing) is a good starting place.Once you isolate the touch commands, I assume you can map them to media commands, as described here: D-Bus_Media_Commands
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So I'm hopelessly lost right now. I found an attractive bluetooth chip from Nordic Semiconductor (the NRF52840) that I want to use for a couple project ideas I have. Now I have an HC-05 module for my arduino, so I'm not entirely lost on programming a bluetooth module perse, but I really need advice on how I can make my own. I want to make a bluetooth module that works exactly like the HC-05 but on a much smaller scale. I'm talking fitbit small. I'm not making a smartwatch or fitbit, but that's relatively the size I would need it to be.
So bottom line to whoever got lost in that mumbling explanation of my hopelessness, I need some advice on how to develop my own Bluetooth module PCB. The onboard chip will be the aforementioned NRF52480. Thank you to anybody who helps!!
Given that you are endeavoring in a very complex task, I would recommend you to start from the reference designs provided by the chip manufacturer. They are very valuable, especially when dealing with RF.
See here and here, for example. About RF design, this talk may be interesting for you as well.
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I'm not quite sure where to post this question, but I think Stack Overflow has a lot of smart people who could help.
I'm wondering if there is a way I can combine programming and electrical circuits. Can I somehow turn my computer into a signal generator to create AC waveforms which I could apply to an external circuit that I've created? Could I then program my computer with say C++ code to change the amplitude/frequency of the waveform (hopefully this if possible doesn't require assembly language which I know nothing about expect that its code that operates more directly with the CPU or something). Basically, I'm looking for a way to combine coding with electrical circuits. Anything will do. I just want to get better at both because they both interest me.
Yes, you can use your audio channel.
You have to consider its frequency response: (theoretical Maximum of 20kHz?)
You also have to buffer the audio output. Use an opamp as a buffer for that. You do not want to overload your audio jack.
You will run into challenges of how "Fast" you can send data to your audio channel. But I think it is possible.
Another way is to use a good old parallel port, IF you have one :). Those are nice to command some electronics.
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I apologize if there is a better place to post this. I recently came across a couple CVS single-use video cameras that I had been using back in 2005. I still have the USB cable I made and now that I've switched to Mac I can use Puretool to extract the old videos from the cameras. The problem I'm having is that I can only hear the audio when viewing the videos with VLC media player. I read on PureTools site, a common problem is that the audio codec used is incompatible with Quicktime and the audio stream needs to be converted. There is a link on their site to a program called FixSound which is purported to fix this, but the link is dead and I've been unable to find any further information about this. If anyone could point me in the right direction, I'd be very grateful. All the videos I'm dealing with are from the first year of my son's life and I'd really like to be able to archive them in a more uniform format. I would think this would be possible to do using Adobe Audition or some other program in Adobe's CS6 Master Collection but I've only dealt with Photoshop, Illustrator, Dreamweaver, Flash & Fireworks. I have no experience with audio or video yet.
Thanks,
Mark
I found a workaround but if anyone has a better suggestion, please post.
I used SoundConverter / GStreamer on my Ubuntu box to convert the audio from the old video to mp3 then combined that with the original video on my iMac using Encore and built it as .f4v (for achiving, I can just build a DVD from Encore). I guess from there I can use Media Encoder to come up with a Quicktime, 3gp, etc... version.
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I need to add some mp3 file playing functionality to my Linux based embedded application. Until now I used a system call (mpg123 -qm list of mp3 files). But now I don't have all the elements of the playlist, but get the next one only when I'm ready with the previous one. With mpg123 it means that I have some stupid noise between the tracks, as I always have to restart the mpg123 binary.
I was looking around for some libraries and found libmad, lame, sdl and co. But they seem to be a bit overcomplicated at first to handle. I found the fmod (http://www.fmod.org/index.php/download) library easy to use. But it's available only in binary format, which doesn't fit my ARM-based target (not to mention the licensing problems). Does anybody know about any similar, open source library capable of playing mp3 files similar to fmod?
mpg123 has an API, perhaps you could use that instead of calling the binary?
OK, finally with the help of houbysoft's hint i found a solution which uses libmpg123 and libao, here, and with some tuning i managed to get pretty smooth file-by-file playing. Thx for the hint!