[Bug 692953] alsasink does not work at all with default value "sync=true" when used with live source that needs synchronization

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=692953
  GStreamer | gst-plugins-base | 1.0.9

--- Comment #156 from Thomas DEBESSE <thomas.debesse at rcf.fr> 2013-09-13 00:10:03 UTC ---
Hi!

> The bug description now states that alsasink doesn't 
> work by default at all, which is surely not true.
> Maybe you could qualify that a little..

Um, yes, it works with sync default value when alsasink is used with
audiotestsrc and with filesrc, when synchronization is not needed.

I corrected the description:

< alsasink does not work at all with default value "sync=true"
> alsasink does not work at all with default value "sync=true" when used with live source that needs synchronization

To summarize the previous 155 comments:

When using alsasink with alsasrc or jackaudiosrc or udpsrc, in a system where
jack and alsa and network are functional, alsasink become noisy then silent in
less than 30 min when used with default sync value "true", and become silent
suddenly in some hours (or days) when used with sync value "false".

The sum of the execution time of all my test pipelines can be counted in
months.

Outside my test environment, I encounter this problem every day, even several
times a day depending on the configuration.

Were tested 2.6 and 3.2 kernel, realtime and no realtime kernel, various
gstreamer version (0.10.30, 0.10.36, 1.0.1, 1.0.4, 1.0.6, 1.0.9, 1.0.10), i386
and x86_64 architectures, various sound card (DSX, Live CT4822, Live CT4790,
XFi, I82801, Audigy, H2n, nVidia, UCA202, Muse LT3, Juli@), various bus (USB,
PCI, PCIe) and various computer, with or without alsa plugin (dmix, plug), with
or without virtual alsa interface on top of physical interface.

I personally checked this problem for over two years (a sound file recorded at
the output of alsasink with default value is provided in the thread, see
Comment #78 ). We can find a previous bug report aged from seven years (see
Comment #139 ).

When someone find an open source code that uses alsasink for live transmission,
the code never use the default (see Comment #130 for examples), or the code
does not work. If the code does not use the default value, you must be very
patient to experience the problem, but with patience the bug always happen. We
have level 3 log with default value, not with the other value. In all cases,
regardless of the value used, alsasink does not work with a live source. It is
only a matter of time to experience the problem.

Public documentations that are not those of the gstreamer project itself
indicate that we should not use the default setting (see Comment #129 or
Comment #138 for examples).

All the other tested modules (jackaudio/alsasrc, udpsrc/sink, rtpopuspay/depay
opusenc/dec, audioresample/convert, etc.) used in tested pipelines that use
alsasink were tested without alsasrc and works fine in all test case.

I think we can say that alsasink does not work at all with (and without) the
default value for synchronization when alsasink must be synchronized. :)

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