[Brendan Long]

The normal way to do this is to add an appsink
<http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-appsink.html>
as playbin's "text-sink".

On 11/12/2013 06:34 AM, Dece Bel wrote:
>
>
> I am trying to read subtitle from a video and want to record the
> timestamp of the subtitled text in the gstreamer pipeline.
> One approach that I have been trying is with the getting the action
> signal on playbin for "get-text-pad"
> and attaching a probe on the pad. Eventually when the callback
> (cb_have_data) is called, I do see the text in the buffer dumped on
> console.
>
> However, I notice that the subtitle on the final rendered video and
> the one dumped from the probe callback are out of sync. 
> Can someone pls suggest how to get the timestamp of the subtitled text
> from the stream or received a sync'ed stream or any other approach.
>
>
> Gracias
> Dece
>
> below is some relevant stripped code that uses the playbin element
> (using gstreamer 1.0)
>
> main() {
>
> // creating the playbin element and setting flags to also play sub-titles
> ...
> ...
> .. 
> ...
>
> g_signal_emit_by_name (data->playbin, "get-text-pad", 0, &txt_pad);
> if(txt_pad) {
> printf("\nwe have a text pad");
> *c**a_pad_data(txt_pad);*
> }
>
> }
>
>
> ///////////////////////////////////////
> // When text pad is added, the below function will attach a probe
>
> */void cb_pad_added(GstPad* pd) {/*
> */  gchar *name;/*
> */  GstCaps *caps = NULL;/*
> */
> /*
> */  name = gst_pad_get_name (pd);/*
> */  g_print ("\nA new pad %s was created\n", name);/*
> */  g_free (name);/*
> */
> /*
> */
> /*
> */  gst_pad_add_probe (pd, GST_PAD_PROBE_TYPE_BUFFER,
> (GstPadProbeCallback) cb_have_data, NULL, NULL);/*
> */
> /*
> */  gst_object_unref (pd);/*
> */
> /*
> */}/*
> */
> /*
>
> ///////////////////////////////////////////////
> // probe call back. Read the buffer an size and then print the buffer
> text to screen.
>
> */static GstPadProbeReturn/*
> */cb_have_data (GstPad          *pad,/*
> */              GstPadProbeInfo *info,/*
> */              gpointer         user_data) {/*
> */
> /*
> */  GstBuffer *buffer;/*
> */  char text_msg[128];/*
> */
> /*
> */  gint sz, sz2;/*
> */  memset(text_msg, 0, sizeof(text_msg));/*
> */  buffer = GST_PAD_PROBE_INFO_BUFFER (info);/*
> */  sz = gst_buffer_get_size(buffer);/*
> */  /*
> */  sz2 = gst_buffer_extract(buffer, 0, text_msg, sz);/*
> */  g_print ("\nBuffer Size is %d, read %d, data: %s", sz, sz2,
> text_msg);/*
> */  return GST_PAD_PROBE_OK;/*
> */}/*
>
>
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