Real Time Device capture and streaming

[DanBrwn]

I am using the windows version of VLC. I have been able to create a capture from my usb camera and UDP stream to another PC using several of the different streaming codecs just fine. The only trouble is that the video is always delayed by a couple of seconds. I don't want this. How can I set the stream up to not have this delay? Is there a setting somewhere that determines the delay? I have used other software, Suns Java media framework, that has practically no delay with RTP MJpeg codecs. It is not a good fit however. Please tell me what I can do. Thanks, Dan

[Gaurav]

Hi Dan,

I am trying exactly the same thing you did (To stream from a usb web cam to another PC) but I have failed. Could you let me know the command line syntax for it. This is what I used:

C:\Program Files\VideoLAN\VLC>vlc.exe -vvv -I rc dshow:// vdev="Logitech QuickCam Express" adev="SoundMAX Digital Audio" size="160x120" --sout=#std{mux=ts,access=udp,url=1.2.3.4}

where the url is that of the machine where I want to see the live feed.

I get the following output:
[00000267] main input debug: `dshow://' successfully opened
[00000268] main stream output debug: adding a new input
[00000275] main private debug: adding a new input
[00000275] mux_ts private debug: adding input codec=I420 pid=68
[00000275] main private error: cannot add this stream
[00000277] main packetizer error: cannot create packetizer output

Does it mean I need to encode the video into a streamble format? Eventually I want to be able to convert it to 3gp? and stream it to a streaming server using RTP? do you know how this can be done?

Kindly advise me on this matter. I would highly appreciate if you gave me the command u used or steps to do the live web cam streaming

Regards,

Gaurav

[zcot]

--udp-caching 0

default value is I think at least 300ms.

there are many caching settings for the various protocols and inputs, outputs..

[DanBrwn]

The command line syntex is similar to yours, the thing that I think you are missing is the transcoding portion. I have not been able to send anything without transcoding it. I have tried but it is apparently necessary. Add something like this for your sout section: ':sout=#transcode{vcodec=WMV2, vb=1024,scale=1}:duplicate{dst=std{access=udp,mux=ts,url=192.168.1.1:9600}}'

ignore the single quotes at the beginning and end. Only here for clarity. The vcodec is whatever codec you are using for the actual video. The vb is the video bitrate. Duplicate creates a copy of the transcoded stream and sends it to dst which we have defined as access method udp, mux=ts, url (computer to receive the stream) 192.168.1.1:9600 on port 9600. On the recieving computer all you have to do is vlc -vvv udp//@9600 to recieve the stream. Good luck, let me know if the stream does not have a 1.5 to 2 second delay. Thanks , Dan

[DanBrwn]

>>--udp-caching 0
Tried this, upd-caching can't really be set to zero however. The source allows 1 or greater only, still setting to 1 really has no noticeable effect anyway.

>>there are many caching settings for the various protocols and inputs, >>outputs..[/quote]
Are there any that will result in a 1.5 to 2 second delay? I am using udp, WMV2 and TS mux.

Thanks, Dan

[micotito]

>>--udp-caching 0
Tried this, upd-caching can't really be set to zero however. The source allows 1 or greater only, still setting to 1 really has no noticeable effect anyway.

>>there are many caching settings for the various protocols and inputs, >>outputs..

Are there any that will result in a 1.5 to 2 second delay? I am using udp, WMV2 and TS mux.

Thanks, Dan[/quote]

It seems to be a delay for the transcoding time, I can't also send anything without enconding. I have tried many options. Found that the first delay is on the Dshow cache, but if I set it to something less that 200 ms, I start having problems with error packet late for something, I need to to set this to 400ms for video and 600ms if wanted audio..

All i want to do is send 320x240 over my local network or maybe to back to back machines.

I can do it with Neetmeeting but also I want to sendit full screen so I use VLC but don't want the Delay.

Now VLC is may default player but can make anything else than play files and internet streams.

Anyone can send something without transcoding o without delay over 100Mbps network?

[DanBrwn]

I have found in the source code where the delay is. It is designed / hard coded for a 1.5 second delay in sout_muxSendBuffer() in stream_output.c . My only trouble is that I don't know all of the GNU tools for compiling / building the source. I am trying to work through it but I come from a Windows / DOS background and can not get a handle on the tools. Do you know how to use the configure, configure.in, automake, etc to build an image?
I suppose if I can get this to work, I will make a suggestion that they incorporate a command line argument to the --sout streaming object to allow setting this up dynamically. It probably makes sense for some uses of the server like you and I.

[aspoon]

With a network camera directly streaming MJPEG, there is still a delay of ~1.5s when viewed from VLC compared to the web interface as directly provided on the camera.

Both VLC and browser uses the same MJPEG source URL, so the delay is not in the stream output for this scenario.

Perhaps the 1.5s is hardcoded in numerous places?

[DanBrwn]

I think this is the case. I am currently looking at the source to discover how to remove some of these. Anyone know if changing the CLOCK_FREQ or INPUT_RATE_DEFAULT is an option. It looks like they are used all over the source for buffering values. There are also a lot of hardcoded values throughout the source. I am currently just looking at changing a couple of the codec implementations for the specific application I have because I dont know what affect changing such a global thing like the CLOCK_FREQ might have. Anyone else interested in live video?

[wsblurch]

I' ve got a similar Problem, but first I want to build a system that grabbs video from a video card like osprey or sensoray. For me it is necessary to have no delay. So I must know wich Grabber Card is the best for that. Perhaps webcams are to slow for no delay.

Does somebody know another solution for streaming in Realtime?

[jntn77]

wsblurch, from what I checked the Osprey 100 (and up) are the best solution for capture cards, and they introduce no delay what so ever.
btw, to my opinion, nor does the webCams.
Now, I see it's been a while, but have you guys get some kind of solution to the delay problem?

[wsblurch]

I searched arround the internet and found something wich could be interesting for all guys who are real time interested. look at http://www.umediaserver.net , my delay was 80ms. The only disadvantage is that it is not very cofortable.