GNOME Bugzilla – Bug 636294
[pulsesink] Introduces artefacts into sound ("scratchy" playback)
Last modified: 2010-12-02 14:35:42 UTC
Hi, Compare the output of the following two audio pipelines: gst-launch-0.10 neonhttpsrc location=http://colin.guthr.ie/bong.ogg ! decodebin ! audioconvert ! pulsesink vs. gst-launch-0.10 neonhttpsrc location=http://colin.guthr.ie/bong.ogg ! decodebin ! audioconvert ! alsasink Both pipelines ultimately go via PulseAudio (as alsa is configured to go via alsa-pulse plugin), but the former (pulsesink) pipeline produces identifiably worse audio even on small samples like the above. It's most noticeable at the start of the playback.
In the alsasink case, gstreamer does the float to int conversion. In the pulsesink case, pulsesink does float to int conversion.
So some more tests: gst-launch-0.10 filesrc location=bong.ogg ! decodebin2 ! audioconvert ! audioresample ! audio/x-raw-int ! pulsesink also causes problems, but: gst-launch-0.10 filesrc location=bong.ogg ! decodebin2 ! audioconvert ! audioresample ! audio/x-raw-int,rate=44100 ! pulsesink does not. So as wtay says the resampler in PA appears to be the problem. Changing the PulseAudio resampler to trivial or src-* seems to be problem free, so but on different speex ones, it appears broken. So the problem is actually in the speex resampler in PA (or in speex itself). Therefore, closing as invalid here.