<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
<br>
<br>
Wim Taymans wrote:
<blockquote cite="mid1146156985.12518.59.camel@localhost" type="cite">
<pre wrap="">On Thu, 2006-04-27 at 18:39 +0200, Benoit Fouet wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
I've read Gstreamer documentation (i.e. Application Development Manual
and Plugin Writer's Guide) and one point remains obscure to me.
I can't figure out how data is synchronized over the pipeline.
e.g. when having a pipeline as simple as an audio file source, a decoder
and an audio plugin, the source is able to provide data much more
quickly than the decoder can work, itself more quickly than the audio
sink is able to flush data on driver.
though, my question is: what is the event that allows an element to
provide data over its source pad ?
is it that gst_pad_push is called in the same thread, and is by the way
blocking the upstream element, or are there other synchronization methods ?
</pre>
</blockquote>
<pre wrap=""><!---->
Yep, pad_push() eventually blocks somewhere downstream, either in a sink
that does
synchronisation or another element that rate controls in one way or
another (queue, based on buffer size, some network element).
All elements in a pipeline share the same clock normally, a typical sink
waits for the clock to reach the propor time corresponding to the buffer
timestamps before rendering a buffer. As soon as the buffer is rendered
(or scheduled for rendering in the case of audio) pad_push() returns and
upstream elements can produce new data.
Hope that explains,
Wim
</pre>
</blockquote>
It does explain, thanks :)<br>
I have a related second question: in case an element has multiple
source pads (let's say 2 for instance), is there a way to have one of
them blocked and the other one allowed to produce new data ?<br>
e.g. if a video source element provides data to both a renderer/display
(rather quick) and an encoder (slower), is it possible that the display
element have access to more frames than the encoder ?<br>
in other words, let's say you can produce 30 frames per second and you
encode at 15 but you want to display 30.<br>
do the downstream elements have to manage themselves to drop frames
they don't need ?<br>
<br>
Regards,<br>
Ben<br>
<br>
<blockquote cite="mid1146156985.12518.59.camel@localhost" type="cite">
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">Thanks,
Ben
-------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
<a class="moz-txt-link-freetext" href="http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642">http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642</a>
_______________________________________________
gstreamer-devel mailing list
<a class="moz-txt-link-abbreviated" href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a>
<a class="moz-txt-link-freetext" href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a>
</pre>
</blockquote>
</blockquote>
</body>
</html>