compat for old sessions with missing plugins (+doc)

diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index f461fe58d19473afc29215a99d688187b242caa9..ce5570057ba1422b4184a9bd6db2f9f0eca94747 100644 (file)
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -1934,7 +1934,9 @@ Route::configure_processors_unlocked (ProcessorStreams* err)
        list< pair<ChanCount,ChanCount> >::iterator c = configuration.begin();
        for (ProcessorList::iterator p = _processors.begin(); p != _processors.end(); ++p, ++c) {
 
-               (*p)->configure_io(c->first, c->second);
+               if (!(*p)->configure_io(c->first, c->second)) {
+                       DEBUG_TRACE (DEBUG::Processors, string_compose ("%1: configuration failed\n", _name));
+               }
                processor_max_streams = ChanCount::max(processor_max_streams, c->first);
                processor_max_streams = ChanCount::max(processor_max_streams, c->second);
 

diff --git a/libs/ardour/unknown_processor.cc b/libs/ardour/unknown_processor.cc
index 4bf4ebeaefe5df60c0c470fcc56a4d3526382d3b..df40d4d04098ec7293a5d46618f2be4b66ef9a57 100644 (file)
--- a/libs/ardour/unknown_processor.cc
+++ b/libs/ardour/unknown_processor.cc
@@ -69,6 +69,40 @@ UnknownProcessor::can_support_io_configuration (const ChanCount &in, ChanCount &
        if (have_ioconfig && in == *saved_input) {
                out = *saved_output;
                return true;
+       } else if (!have_ioconfig) {
+               /* pass for old sessions.
+                *
+                * session load assumes processor config succeeds.
+                * if initial configuration fails, processors downstream
+                * remain unconfigured and at least the panner will assert/segfault.
+                *
+                * This may still result in impossible setup, however
+                * Route::configure_processors_unlocked() ignores configure_io() return value
+                * in the inner loop and configures all available processors.
+                *
+                * It can still lead to segfaults IFF the track has no inputs and this is a
+                * generator (processor_max_streams will be zero).
+                */
+               PBD::warning << _("Using plugin-stub with unknown i/o configuration for: ") << name() << endmsg;
+#if 0
+               /* No output channels are fine (or should be, there may be edge-cases with e.g sends).
+                *
+                * Discussion needed.
+                *
+                * This is the safer option (no audio output, no possible damage)
+                * and the way to go in the long run.
+                * An even better solution is to disable the route if there are missing plugins
+                * and/or impossible configurations.
+                *
+                * Currently no output channels results in awkward GUI route display and also
+                * breaks semantics in mixbus (which assumes that the route has channels required
+                * for the always present mixer-strip plugin).
+                */
+               out = ChanCount ();
+#else
+               out = in;
+#endif
+               return true;
        }
        return false;
 }