<div dir="ltr"> The actual problem occured in own C code but can be boiled down to the following gst-launch pipelines. Are "channels=(int)1, channel-mask=(bitmask)0x0000000000000000" valid caps for mono audio? Depending on the answer to that that question either avdec_g722 or audioconvert needs to be fixed IMHO. Can anybody confirm this ? 1) Good pipeline root@ipac:~# GST_DEBUG=3 gst-launch-1.0 audiotestsrc ! avenc_g722 ! avdec_g722 ! audioconvert ! audio/x-raw, channels=1 ! fakesink Setting pipeline to PAUSED ... Pipeline is PREROLLING ... 0:00:00.182954856 694 0xf0120 FIXME default gstutils.c:3622:gst_pad_create_stream_id_printf_valist:<audiotestsrc0:src> Creating random stream-id, consider implementing a deterministic way of creating a stream-id Pipeline is PREROLLED ... Setting pipeline to PLAYING ... New clock: GstSystemClock ^CCaught interrupt -- handling interrupt. Interrupt: Stopping pipeline ... Execution ended after 5513031006 ns. Setting pipeline to PAUSED ... Setting pipeline to READY ... Setting pipeline to NULL ... Freeing pipeline ... 1) Bad pipeline root@ipac:~# GST_DEBUG=3 gst-launch-1.0 audiotestsrc ! avenc_g722 ! avdec_g722 ! audioconvert ! audio/x-raw, channels=2 ! fakesink Setting pipeline to PAUSED ... Pipeline is PREROLLING ... 0:00:00.182148390 696 0xf0120 FIXME default gstutils.c:3622:gst_pad_create_stream_id_printf_valist:<audiotestsrc0:src> Creating random stream-id, consider implementing a deterministic way of creating a stream-id 0:00:00.192402311 696 0xf0120 WARN basetransform gstbasetransform.c:1348:gst_base_transform_setcaps:<audioconvert0> transform could not transform audio/x-raw, rate=(int)16000, channels=(int)1, channel-mask=(bitmask)0x0000000000000000, format=(string)S16LE, layout=(string)interleaved in anything we support 0:00:00.194904758 696 0xf0120 WARN basetransform gstbasetransform.c:1348:gst_base_transform_setcaps:<audioconvert0> transform could not transform audio/x-raw, rate=(int)16000, channels=(int)1, channel-mask=(bitmask)0x0000000000000000, format=(string)S16LE, layout=(string)interleaved in anything we support 0:00:00.196186498 696 0xf0120 WARN basesrc gstbasesrc.c:2812:gst_base_src_loop:<audiotestsrc0> error: Internal data flow error. 0:00:00.196949439 696 0xf0120 WARN basesrc gstbasesrc.c:2812:gst_base_src_loop:<audiotestsrc0> error: streaming task paused, reason not-negotiated (-4) ERROR: from element /GstPipeline:pipeline0/GstAudioTestSrc:audiotestsrc0: Internal data flow error. Additional debug info: gstbasesrc.c(2812): 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 ... root@ipac:~# </div>