How to capture a still image while previewing live video?

[Mike Mitchell]

Paul,

First Wes was right that you need multifilesink, otherwise your output will
be appended, not overwritten. I could not use your TIVidResize or TIImgenc1.
So I used the generic modules. Below you will find a linux example that
creates a JPG for every second of the incoming video.  Notice the caps on
either side of the videorate element.  These tell videorate that it must
drop frames to meet your criterion, and with silent=FALSE you can see it
will drop 95/100. I think it is working as you would expect . At first I
guessed it would drop 97 frames and forward only 30,60 and 90.  But perhaps
it's forwarding frames 1,31,61,91 and an EOS frame.

*Mike Mitchell, MBA*
Principal
Panometric LLC

gst-launch -vt --gst-plugin-spew \
 videotestsrc num-buffers=100  \
! 'video/x-raw-yuv, framerate=30/1' \
! videorate silent=FALSE \
! jpegenc \
! 'image/jpeg, width=(int)320, height=(int)240, framerate=(fraction)1/1,
pixel-aspect-ratio=(fraction)1/1' \
! multifilesink location=output-%05d.jpg
ls -al outpu*.jpg



---------- Forwarded message ----------
From: Paul Stuart <Paul_Stuart at seektech.com>
To: "gstreamer-devel at lists.freedesktop.org" <
gstreamer-devel at lists.freedesktop.org>
Date: Tue, 13 Sep 2011 16:23:51 -0700
Subject: How to capture a still image while previewing live video?

Hi,****

  We need to simultaneously capture/preview video on a TI DM365 while
asynchronously taking JPEG stills from the same video stream.  Playing
around with gst-launch, it only seems to work correctly when v4l2src
num-buffers=1. Sample working pipeline:****

gst-launch -v v4l2src  num-buffers=1 always-copy=FALSE  input-src=composite
\
! TIVidResize contiguousInputFrame=TRUE \
! 'video/x-raw-yuv,width=(int)736,height=(int)480' \
! queue \
! TIImgenc1  iColorSpace=UYVY oColorSpace=YUV420P qValue=75
engineName=codecServer \
! queue \
! filesink location=output.jpg****

 ****

If I modify the above to remove num-buffers=1, or even just set
num-buffers=2, it hangs and never produces a valid JPEG. I would have
expected it to just overwrite output.jpg****

 ****

If, I change this to something that is, for instance, previewing the video
at the same time, things break as well. Sample Pipeline:****

gst-launch -v v4l2src always-copy=FALSE  input-src=composite \
! queue \
! tee name= t \
! 'video/x-raw-yuv,width=(int)736,height=(int)480' \
! tidisplaysink2 video-standard=vga display-output=lcd mmap-buffer=FALSE
dma-copy=TRUE \
t. \
! queue \
! 'video/x-raw-yuv,width=(int)736,height=(int)480' \
! videorate \
! TIImgenc1  iColorSpace=UYVY oColorSpace=YUV420P qValue=75
engineName=codecServer \
! filesink location=output.jpg****

** **

Is it possible to create a gstreamer pipeline using “standard” parts to
accomplish what I need, or will I need to modify my JPEG encoder element to
make this work?****

** **

Thanks!****

Paul****

** **
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