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<div class="moz-cite-prefix">On 08/19/2015 03:46 PM, James Felix
Black wrote:<br>
</div>
<blockquote
cite="mid:1440010011.2772906.360579729.60567105@webmail.messagingengine.com"
type="cite">
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<div>On Wed, Aug 19, 2015, at 13:52, Thiago Santos wrote:<br>
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<div>On 08/19/2015 02:42 PM, James Felix Black wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1440006164.2756501.360488729.41C9CF17@webmail.messagingengine.com">
<div>Linux ARM (nVidia Jetson TK1), gstreamer-1.5.2, Qt 5.5,
qt-streamer 1.2.0<br>
</div>
<div> </div>
<div>I have a simple X11 application that I'm working, based
for now on the qt-gstreamer demo code [1] that plays a video
to the screen, and snapshots "interesting" frames to disk.
I'm using Qt and the qt-gstreamer package, and I am able to
access sample data directly off the pipeline (using the
"sample" property at a given time), and write the raw video
to disk as such:<br>
</div>
<div> </div>
<div>
<div> QGlib::Value val = pipeline->property("sample");<br>
</div>
<div> GstSample * v = (GstSample *)g_value_get_boxed(val);<br>
</div>
<div> </div>
<div> // write the contents of v's memory buffer to disk
....<br>
</div>
<div> </div>
<div>What I get is a raw file of 4bytes * 1920 * 1080.
That's cool! But what I want to do is:<br>
</div>
<div> </div>
<div> GstCaps * jpegCaps =
gst_caps_new_simple("image/jpeg", "width", G_TYPE_INT,
640, NULL);<br>
</div>
<div> GError * err;<br>
</div>
<div> GstSample * jpeg = gst_video_convert_sample(v,
jpegCaps, 100, &err);<br>
</div>
<div> </div>
<div>... and then write the contents of *that* sample to
disk, instead. However, if I do that conversion, jpeg is
null and the error is:<br>
</div>
<div> </div>
<div>"Cannot find any image encoder for caps image/jpeg"<br>
</div>
<div> </div>
<div>OK, that seems fair. But my pipeline (again see the
example code at [1]) is constructed as such:<br>
</div>
<div> </div>
<div> m_pipeline =
QGst::ElementFactory::make("playbin").dynamicCast<QGst::Pipeline>();<br>
</div>
<div> </div>
<div>My question then becomes: how should I approach this
problem? Should I modify the pipeline? I see that there's
a "convert-sample" signal on playbin; is that what I
should be using?<br>
</div>
<div> </div>
<div>Any light anyone can shed would be most welcome.<br>
</div>
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</blockquote>
<div> </div>
<div> Do you have jpegenc (or any other jpeg encoder) in your
system? gst-inspect-1.0 jpegenc should show it. Or
gst-inspect-1.0 |grep jpeg.<br>
</div>
<div> </div>
</blockquote>
<div> </div>
<div>I was missing jpegenc; thanks. Having installed it, I now get
an "Internal data flow error". <br>
</div>
<p class="p1"><span class="s1">default
convertframe.c:325:gst_video_convert_sample:</span><span
class="s2"> Could not convert video frame: Internal data flow
error.</span><br>
</p>
<div>This is using a one-second timeout on the frame conversion
(GST_SECOND). Hmmm. Any pointers here?<br>
</div>
</blockquote>
I'd recommend using GST_DEBUG to get some log and check what exactly
was the error.<br>
<br>
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<br>
<br>
<pre class="moz-signature" cols="72">--
Thiago Sousa Santos
Senior Multimedia Engineer, Open Source Group
Samsung Research America - Silicon Valley</pre>
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