Hi, gstreamer-devel:     Actually, I don't get what your problem is. Maybe this is because a language limitation. if you wanna use osxaudiosink, add converter or any other filter elements into your pipeline, otherwise the not-negotiation error occurs. This is the sample pipeline from osxaudiosink's manual: gst-launch -v filesrc location=sine.ogg ! oggdemux ! vorbisdec ! audioconvert ! audioresample ! osxaudiosink     I think your can read gstreamer developer guide and maybe you will figure out the answer yourself while reading it. Eric Zhang <div class="gmail_quote">2008/11/11 Sjoerd Op 't Land <<a href="mailto:sjoerd@intercue.nl">sjoerd@intercue.nl</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hello all, I am new to gstreamer, so please forgive me if the errors encountered are due to my inexperience. I am running Mac OS 10.5.5 on a MacBook Core 2 Duo and I compiled gstreamer, gst-plugins-base and gst-plugins- good from cvs (<a href="http://0.10.21.1" target="_blank">0.10.21.1</a>). To start off, I wanted to create an audio loopthrough. First, I tried to get the output to work. With a little modification, I was able to produce a sine:  > gst-launch audiotestsrc ! audioconvert ! audio/x-raw- float,channels=2,width=32,depth=32 ! osxaudiosink (My first attempt failed, I don't know whether this is expected behaviour:  > gst-launch audiotestsrc ! osxaudiosink Setting pipeline to PAUSED ... Pipeline is PREROLLING ... ERROR: from element /GstPipeline:pipeline0/ GstAudioTestSrc:audiotestsrc0: Internal data flow error. Additional debug info: gstbasesrc.c(2292): gst_base_src_loop (): /GstPipeline:pipeline0/ GstAudioTestSrc:audiotestsrc0: streaming task paused, reason not-negotiated (-4) ERROR: pipeline doesn't want to preroll. Setting pipeline to NULL ... FREEING pipeline ...) The reason I am mailing you, is that I can't seem to get osxaudiosrc to function, tried various stream types and convert/resample options. The command line suggested in the source code unfortunately does not function:  > gst-launch -v -m osxaudiosrc ! fakesink Setting pipeline to PAUSED ... ERROR: Pipeline doesn't want to pause. Got Message from element "fakesink0" (state-changed): GstMessageState, old-state=(GstState)GST_STATE_NULL, new- state=(GstState)GST_STATE_READY, pending- state=(GstState)GST_STATE_VOID_PENDING; Got Message from element "osxaudiosrc0" (state-changed): GstMessageState, old-state=(GstState)GST_STATE_NULL, new- state=(GstState)GST_STATE_READY, pending- state=(GstState)GST_STATE_VOID_PENDING; Got Message from element "pipeline0" (state-changed): GstMessageState, old-state=(GstState)GST_STATE_NULL, new- state=(GstState)GST_STATE_READY, pending- state=(GstState)GST_STATE_PAUSED; Got Message from element "osxaudiosrc0" (error): GstMessageError, gerror=(GstGError)(NULL), debug=(string)"gstbasesrc.c\(2484\):\ gst_base_src_start\ \(\):\ /GstPipeline:pipeline0/ GstOsxAudioSrc:osxaudiosrc0:\012Check\ your\ filtered\ caps\,\ if\ any"; ERROR: from element /GstPipeline:pipeline0/ GstOsxAudioSrc:osxaudiosrc0: Could not negotiate format Additional debug info: gstbasesrc.c(2484): gst_base_src_start (): /GstPipeline:pipeline0/ GstOsxAudioSrc:osxaudiosrc0: Check your filtered caps, if any Setting pipeline to NULL ... FREEING pipeline ... Thanks in advance for any suggestions. Again, I apologise beforehand if this is an error of mine, due to my inexperience with GStreamer. Best regards, Sjoerd Op 't Land ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world <a href="http://moblin-contest.org/redirect.php?banner_id=100&url=/" target="_blank">http://moblin-contest.org/redirect.php?banner_id=100&url=/</a> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> </blockquote></div>