[lug] Video recording with continuous playback

Wed Mar 7 07:56:09 MST 2018

I don't know of anything that does this out of the box, and I haven't found
anything in some cursory googling.

It would take some experimentation, but I would think if you had something
that was streaming to disk, then just waited 60 seconds to start playing
that stream, it would give you the delay you want. I would just experiment
with the simplest tools you can find to do these things, and glue them
together with a script along the lines of:

recording_program to file
sleep 60
playback_program file

Then you just need to remember to nuke the file.

I for playback, either vlc or mplayer are probably good starting points.
For recording, I haven't used anything myself, but guvcview seems to be the
go-to.

As far as hardware, really anything made in the last decade or so should be
able to handle it, so long as it has sufficient space to buffer the video
for a whole session and you are recording at 1080p or lower resolution. I
own a logitech 920 webcam, and it works well, so I second that rec.

QH

On Wed, Mar 7, 2018 at 7:36 AM, Steve Sullivan <steve.sullivan at mathcom.com>
wrote:

> Thanks for the comments!
>
> I'm a novice at video so probably my question wasn't clear.
> What I'm looking for is, all within a single small Linux laptop:
>
>   * Camera, such as USB camera or tablet internal camera.
>     Logitech C920 was recommended -- USB connected would be fine.
>
>   * Software to continuously buffer the video stream, adding
>     60 seconds delay.
>
>   * Playback, to continuously display the delayed stream
>     on the tablet's screen.  VLC?
>
> So what you see on the screen is whatever the camera saw 60 seconds ago.
> Almost certainly we won't have any network access.
>
> Do you have recommendations on how to do the video buffering,
> or what small laptop might be appropriate?
>
> Many thanks,
>
> Steve
>
>
> On Wed, Mar 07, 2018 at 12:57:19AM -0700, Bear Giles wrote:
> > No networking? Then I guess transmitting a signal to a transceiver 30
> > light-seconds out wouldn't work either.
> >
> > On Tue, Mar 6, 2018 at 4:59 PM, <stimits at comcast.net> wrote:
> >
> > > You might find a USB webcam using the standard "USB Video Class" is a
> very
> > > simple solution if you don't mind adding a USB camera (e.g., the
> Logitech
> > > C920). So long as it doesn't take a custom driver you could install
> (and
> > > capture) with "guvcview". There are other applications which can work
> with
> > > USB standard cameras, this particular one is easy and reliable. I
> suspect
> > > there would be no issue getting the application to work with all kinds
> of
> > > smaller/mobile devices if they run Linux.
> > >
> > > ----- Original Message -----
> > > From: Steve Sullivan <steve.sullivan at mathcom.com>
> > > To: lug at lug.boulder.co.us
> > > Sent: Tue, 06 Mar 2018 22:17:40 -0000 (UTC)
> > > Subject: [lug] Video recording with continuous playback
> > >
> > > Hi, I want to put a cheap netbook / chromebook / ipad / whatever
> > > on a tripod recording divers on a team at the swimming pool.
> > > There'd be simultaneous playback, delayed about 60 seconds later.
> > > That way the divers could hop out of the pool and see what
> > > they've just done.
> > > There are apps that do this for phones, like
> > > https://itunes.apple.com/us/app/bam-video-delay-for-
> coaching-and-personal-
> > > training/id517673842?mt=8
> > > https://chrome.google.com/webstore/detail/replay-it-sports-video-de/
> > > dcdhimjnicocbcjhmfcjlooncidccanl?hl=en
> > > Then I thought, why not Linux? Does anyone have experience
> > > with this? What hardware and software would you recommend?
> > > Many thanks,
> > > Steve
> > > --
> > > ========================================
> > > Steve Sullivan steve.sullivan at mathcom.com
> > > 720-587-7498 <(720)%20587-7498> http://www.mathcom.com
> > > ========================================
> > > _______________________________________________
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>
> --
>
> ========================================
> Steve Sullivan      steve.sullivan at mathcom.com
> 720-587-7498        http://www.mathcom.com
> ========================================
> _______________________________________________
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