topic Re: Record RTSP audio stream in LabVIEW

Record RTSP audio stream

pRoFiT — Sat, 27 Feb 2010 01:30:31 GMT

Okay im trying to automate an audio test on a IP video encoder. I can find the rtsp stream location but im not sure were to start on retrieving the stream. I have VLC playing the stream...i guess i could run a command line vlc to save a 5 second stream? then open the file for evaluation? What i would like is direct stream copy in labview so that i dont need 3rd party tools installed.

Maybe a .net call to do this would help?

Thanks in advance.

-Corey

Re: Record RTSP audio stream

pRoFiT — Sun, 28 Feb 2010 09:11:27 GMT

bump? nothing?

Re: Record RTSP audio stream

rolfk — Mon, 01 Mar 2010 08:36:42 GMT

While you could implement RTSP directly in LabVIEW at least to the point that you can receive a simple voice stream, this is not trivial indeed. Especially since RTSP allows for various compression negotiation and what else and implementing compression in LabVIEW itself is not a very efficient idea, mostly in terms of development time, but it's also not easy to get good performance when dealing on bit level with data.

So personally I would get a good RTSP Open Source shared library and interface that to LabVIEW. This is also not the most easy approach but I would do it because it keeps the option open to reuse it on other LabVIEW platforms than Windows

Using .Net certainly will work too, finding the right component and API documentation is probably the most challenging part. Integrating it into LabVIEW if you only want to retrieve a limited chunk of data should be fairly straight forward, but for seamless streaming into LabVIEW it would certainly require some more advanced programming level, where you would have to interface with some sort of double buffered API. It's main disadvantage in my view is its strict reliance on modern Windows versions only, possibly even limiting your solution to the greatest and newest Windows platform, depending on the .Net dependencies your component has.

Message Edited by rolfk on 03-01-2010 09:36 AM

Re: Record RTSP audio stream

zou — Mon, 01 Mar 2010 19:20:08 GMT

Corey,

Other software, such as audio Logger, let you copy the recording file before it finish recording. So you can evaluate the copy.

Don't know if VLC will let you do that.

I just started to play with VLC last week. How do you run a command line vlc to save a 5 second stream?

George

Re: Record RTSP audio stream

pRoFiT — Tue, 02 Mar 2010 23:39:33 GMT

good question on the 5 second stream recording.

I've spent the last hour trying to figure it out.

Basicly with the VLC plugin you do a invoke node "Add Target" then enter in url to the stream and options....this is where im at. The options are tricky and complicated. Every possible file type is available.

So you need to know what you want to output. This is what i've got but it doesn't work.

For options im creating an array of string with this in it.

--sout '#transcode{vcodec=h264, vb=800, scale=1, deinterlace=0, acodec=aac, ab=128, channels=1, samplerate=44100}:standard{access=file,mux=mp4,dst='c:\video_test.mpg'}'

I've tried several variations to this with no luck. double quotes, single quotes, different vcodec, etc... I can get it to work in VLC so for the most part so these settings should work. And this is just one option. You can add more if needed. like fps output, etc... If i figure out the save file i will report the vi 🙂

Message Edited by pRoFiT on 03-02-2010 05:38 PM

edit: not sure why the single spaces are so big? It was a copy paste?

Message Edited by pRoFiT on 03-02-2010 05:39 PM

Re: Record RTSP audio stream

pRoFiT — Thu, 04 Mar 2010 07:26:46 GMT

Well I've spent some time working on this with no luck....I did find a post somewhere that said VLC's activeX does not have recording support? But I could not find anything from vlc to support that. Running wireshark to watch network traffic and streaming video gave me a rough idea of what I need to send and receive using TCP calls. And after reading through the basic RTSP standards it seems simple enough. Only issue now would be how to take the streaming h.264 video and display it 🙂 Probably more work then I really want to do.

Running VLC from the command line works but there is no way to stop it or give it a seconds to record option. Maybe a workaround could be to kill the task after a couple seconds. But that would not be very stable or repeatable.

Next I need to see if there is anything else that has activex RTSP streaming. Something that will allow me to save the stream or dump it strait into labview. Seems VLC is the dominant application for this stuff.

Any help from you guys would be great. I dont care if its allot of work and tons of subvi's. I just need anything. That's my best "not sounding desperate" plea.

-Corey aka pRoFiT

Re: Record RTSP audio stream

rolfk — Thu, 04 Mar 2010 07:44:41 GMT

Yep, RTSP itself isn't that complicated and would be quite easy to implement. It's the various stream formats that are the difficult task with all sorts of compression and what else, which is definitely not something you want to implement in LabVIEW. The development of those algorithmes is tricky, complicated and on a level where you almost certainly will run into performance troubles with LabVIEW, since it's not as ideal for complicated bit banging operations as C and sometimes even assembly is used to get the desired performance.

I still beleive that ActiveX while a promising idea at first is not the ideal solution. It would be quite quick and not to much hassle if there was a good ActiveX component with a well defined API but I haven't seen that yet. In addition I do mislike the lockin into Windows that wouldencompass.

If I had the need for that, I would probably look at the code at http://www.live555.com and incorporate that as shared library module into a LabVIEW library. Possibly you could even use their openRTSP application as standalone client and redirect its standard output somehow.

Re: Record RTSP audio stream

pRoFiT — Fri, 05 Mar 2010 07:10:13 GMT

Thanks rolfk,

Yah the last couple days of looking into RTSP I keep ending back at live555. Looks like they are monopolizing on the RTSP streams 🙂 I pulled there source down to look at. Maybe if I have time to compile it I will try to make it work for me. Always good to learn something new. Specially since I work in video ip security. I might as well understand the underlying code im testing.

-Corey

Re: Record RTSP audio stream

rolfk — Fri, 05 Mar 2010 07:18:29 GMT

pRoFiT wrote:
Thanks rolfk,

Yah the last couple days of looking into RTSP I keep ending back at live555. Looks like they are monopolizing on the RTSP streams 🙂 I pulled there source down to look at. Maybe if I have time to compile it I will try to make it work for me. Always good to learn something new. Specially since I work in video ip security. I might as well understand the underlying code im testing.

-Corey

No they definitely do not monopolize the RTSP market but if you look for an Open Source RT(S)P library that is still actively maintained you do end up there.

And they seem to be commited to it, as is evidenced by projects relying on it for their RTSP stream such as VLC and MPlayer.

If I had a real need for this and more importantly a useful test setup to actually test it, I would probably have done a LabVIEW library for it some time ago.

Message Edited by rolfk on 03-05-2010 08:18 AM

Re: Record RTSP audio stream

zou — Fri, 05 Mar 2010 15:40:24 GMT

I managed to record mp3 file. I only need audio part.

It appears that VLC let you play the mp3 file while recording.

I can use WMP to play the mp3 file while recording using VLC.

Close the VLC window will make it stop recording.

lvwutil32.zip from NI can stop a running application.

Re: Record RTSP audio stream

pRoFiT — Sat, 13 Mar 2010 02:57:20 GMT

Zou,

Well in that case I could run a command line VLC and then end it after 10 seconds. Seems like the easiest way right now. I think user32.dll in windows will let you kill tasks. i know there is an easy way in .net to start an app and keep the process id so you can kill it later. I used that once to spawn off a bunch of ghostsrvr apps for imaging multiple pc's 🙂

Anyways, thanks. I think this is my major blocking point for a fully automated video encoder test application.

Re: Record RTSP audio stream

rolfk — Sat, 13 Mar 2010 07:04:33 GMT

This VI works similar to the System Exec VI but also returns the PID of the process so you can later kill it.

Message Edited by rolfk on 03-13-2010 08:04 AM

Re: Record RTSP audio stream

zou — Sun, 14 Mar 2010 21:15:08 GMT

Corey,

.net way is the best to terminate a process. But don't "kill" the process, you can use the id to get the main window handle. Close the main window to terminate the process gracefully. No worry about memory leak, and re-start the application again without trouble.

This method is just a wrap around the C/WinAPI method (Rolf used in his VIs) I think. I used C/WinAPI method five years ago ~~to torture~~ to test Intel chips: start/stop an application repeatedly, and in multiple instance.

I moved on to VLM now. It can handle multiple instance of VLC, and for multiple source.

Re: Record RTSP audio stream

pRoFiT — Wed, 24 Mar 2010 01:40:40 GMT

Thanks for the LvUtils.zip file. I'm am getting back to this and thought, maybe i should just get a working run and kill process working. Then i noticed you posted this file 🙂

I've setup a simple vi, using your files, with:

"c:\program files\VideoLan\vlc\vlc.exe" rtsp://192.168.1.28/stream1 --sout=#transcode{vcodec=h264,vb=800,scale=1,acodec=mp3,ab=128,channels=1,samplerate=44100}:std{access=file,mux=mp4,dst=c:\test.mpg}

And that starts the vlc no problem. But if i use the kill process then it does not close the file or something and i dont get video from test.mpg? If i run from command line and click on the X or stop or file/close then the file saves correctly. There has to be a way to maybe use "findwindow" and "sendmessage" to tell VLC to close? I think i have those already put together for labview somewhere 🙂

-Corey

Re: Record RTSP audio stream

pRoFiT — Wed, 24 Mar 2010 02:05:33 GMT

Okay user32.dll findwindow and sendmessage seem to work. Here is a snippet. also used your create function. I was hoping the PID and the hwnd would be the same and then i wouldn't need findwindow...but they are different. I may need the PID to verify the process closed...Not sure yet.

p.s. ignore the &H112 that was hex command for the sendmessage to close window. shown above as 112

-Corey

Re: Record RTSP audio stream

rolfk — Wed, 24 Mar 2010 08:48:41 GMT

No the PID is the process ID. It is a unique Windows kernel ID for a process. But a process can have MANY windows, so there is no way they could be the same. Also processes are very low level kernel objects, almost at the basic of the Windows kernel together with events, semaphores, threads and memory. Windows are GDI (Graphics Device Interface) objects, at least 2 layers higher, that make use of many kernel services too but also of other subssytems, one of them being the graphics output system, and handling the basic user input such as mouse, keyboard and such too.

There are functions to enumerate the windows of a given process but they use callback functions and are therefore not feasable to use directly in LabVIEW without some small C wrapper.

Re: Record RTSP audio stream

omppu — Fri, 10 Feb 2012 10:50:11 GMT

Thanks for posting the solution.

I'm having problem with user32.dll: labview crashes the moment I run my vi that uses that dll. (WIN7 normal user account)

Could you tell what setting do you use for the call library function? Mine are attached to this post.

Re: Record RTSP audio stream

omppu — Fri, 10 Feb 2012 11:22:13 GMT

Could you post the code for the solution please??

Re: Record RTSP audio stream

pRoF1T — Tue, 02 May 2017 01:24:29 GMT

Kind of late 🙂 like 5 years late. but hey, maybe this will help someone.