[gst-devel] Video freeze

[sudarshan bisht]

        I want to suggest you something. Instead of creating  elements at
the time of taking screenshot , why don't you create them already, add into
bin and then link them later when you want to take screen shot. And
obviously by this approach you save some time in taking screenshot.

       And try to use bin for set of elements, for example screenshot_bin
having related elements and so on. This makes your code easy to read and
debug.




On Mon, Jan 3, 2011 at 9:57 AM, lithium <cmaster2 at hotmail.com> wrote:

>
> I've been writing a tv capture program. Basically by the end of it i'm
> hoping
> to have the gstreamer stuff setup somewhat like this:
>
> /*
>                                /----queue----xvimagesink //screenoutput
> v4l2src---------tee-----
>                                \----queue----filesink //screenshot
>                                \----queue----\
>                                                    ----multiplexer
> ---filesink //recording
>                                /----queue----/
> alsasrc----------tee-----
>                                \----queue----alsasink //playback from
> capture if needed
> */
>
> At the moment i've implemented the top video branch and am now working on
> the screenshot one.
> I've been using a combination of gtk and gstreamer to write the program.
>
> When the program starts I call the 'openVideoPipeline' function (see below)
> and on clicking the screenshot button in my gtk window it runs the
> 'take_screenshot' function. The problem I am having is that when I press
> the
> screenshot button it causes the screen output to freeze. The file is not
> created by the filesink. I have found that when i click my button that
> causes the tv card options menu to be created and drawn it causes the
> screen
> output to resume playing and the file to be written. The only functions
> used
> from gstreamer in the tv card menu are 'gst_tuner_list_channels',
> 'gst_tuner_list_norms', and 'gst_tuner_get_norm'. It is very likely I am
> going about taking screenshots the wrong way, if someone has a better idea
> please suggest it. Otherwise it would be good if someone has any idea whats
> causing the video to freeze.
>
> I have tried setting the pipeline to playing again after unlinking the
> screenshot pads but it didn't change anything.
>
> int openVideoPipeline(videoIOStruct *videoIO)
> {
>        //create elements
>        videoIO->pipeline = gst_pipeline_new("tvVideo");
>        videoIO->vidSrc = gst_element_factory_make("v4l2src", "source");
>        GstElement *vidSink = gst_element_factory_make("xvimagesink",
> "sink");
>        videoIO->tee = gst_element_factory_make("tee", "splitter");
>        GstElement *vidQueue = gst_element_factory_make("queue", NULL);
>
>        if (!videoIO->pipeline || !videoIO->vidSrc || !vidSink ||
> !videoIO->tee ||
> !vidQueue)
>                return 0;
>
>        //set arguments
>        g_object_set(videoIO->vidSrc, "device", videoIO->devName, NULL);
>
>        gst_bin_add_many(GST_BIN(videoIO->pipeline), videoIO->vidSrc,
> videoIO->tee,
> vidQueue, vidSink, NULL);
>
>        videoIO->videoScreenPad = gst_element_get_request_pad(videoIO->tee,
> "src%d");
>        GstPad *staticOutputPad = gst_element_get_static_pad(vidQueue,
> "sink");
>
>        //link stuff
>        gst_pad_link(videoIO->videoScreenPad, staticOutputPad);
>
>        gst_object_unref(GST_OBJECT(videoIO->videoScreenPad));
>
>        gst_element_link(videoIO->vidSrc, videoIO->tee);
>
>        gst_element_link(vidQueue, vidSink);
>
>        if (!videoIO->pipeline)
>                return 0;
>
>        return 1;
> }
>
> void close_screenshot(GstElement *jpegEncode, videoIOStruct *videoIO)
> {
>        GstPad *pad1 = GST_PAD(g_object_get_data(G_OBJECT(jpegEncode),
> "videoScreenshotPad"));
>        GstPad *pad2 = GST_PAD(g_object_get_data(G_OBJECT(jpegEncode),
> "staticOutputPad"));
>        gst_pad_unlink(pad1, pad2);
> }
>
> void take_screenshot(GtkWidget *widget, videoIOStruct *videoIO)
> {
>        GstElement *jpegOutput = gst_element_factory_make("filesink",
> "jpegoutput");
>        GstElement *jpegQueue = gst_element_factory_make("queue",
> "jpgqueue");
>        GstElement *jpegEncode = gst_element_factory_make("jpegenc",
> "jpegencoder");
>
>        if (!jpegOutput || !jpegQueue || !jpegEncode ||
> !videoIO->jpegPipeline)
>                return;
>
>        //set arguments
>        g_object_set(jpegOutput, "location", "test.jpg", NULL);
>
>        //link stuff
>        gst_bin_add_many(GST_BIN(videoIO->pipeline), jpegEncode, jpegQueue,
> jpegOutput, NULL);
>
>        gst_element_link_many(jpegQueue, jpegEncode, jpegOutput, NULL);
>
>        //gst_element_set_state(videoIO->jpegPipeline, GST_STATE_PLAYING);
>
>        g_signal_connect(jpegEncode, "frame-encoded",
> G_CALLBACK(close_screenshot),
> videoIO);
>
>        GstPad *videoScreenshotPad =
> gst_element_get_request_pad(videoIO->tee,
> "src%d");
>        GstPad *staticOutputPad = gst_element_get_static_pad(jpegQueue,
> "sink");
>        g_object_set_data(G_OBJECT(jpegEncode), "videoScreenshotPad",
> videoScreenshotPad);
>        g_object_set_data(G_OBJECT(jpegEncode), "staticOutputPad",
> staticOutputPad);
>
>        gst_pad_link(videoScreenshotPad, staticOutputPad);
> }
>
> --
> View this message in context:
> http://gstreamer-devel.966125.n4.nabble.com/Video-freeze-tp3171570p3171570.html
> Sent from the GStreamer-devel mailing list archive at Nabble.com.
>
>
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-- 
Regards,

Sudarshan Bisht
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