The error messages are not helpful in diagnosing what's broken here:
What can be done to make Pitivi and gstreamer work better together?
Should I just give up on Pitivi and go with another tool?
ERROR [15963] [0x7fb986aed700] "<Pipeline at 0x22333d0>" pipeline Sep 18 19:31:14 _errorObject: error from /GstPipeline:pipeline1/GstBin:bin1/GnlComposition:gnlcomposition3/GnlSource:gnlsource: AudioTestSourceFactory3/GstBin:bin5/GstAudioTestSrc:real-audiotestsrc (__main__.GstAudioTestSrc): GStreamer encountered a general stream error. (gstbasesrc.c(2507): gst_base_src_loop (): /GstPipeline:pipeline1/GstBin:bin1/GnlComposition:gnlcomposition3/GnlSource:gnlsource: AudioTestSourceFactory3/GstBin:bin5/GstAudioTestSrc:real-audiotestsrc:
streaming task paused, reason not-negotiated (-4)) (/usr/lib/pitivi/python/pitivi/log/loggable.py:30)
