pre-process (silence) before export to flush reverb tails etc.

[ardour.git] / libs / ardour / session_export.cc

diff --git a/libs/ardour/session_export.cc b/libs/ardour/session_export.cc
index 62eb61ab83e16654eb13890d2cddbcbe9e5feb50..6b54db3826b8d923e16b78896d2ac39dea1a8214 100644 (file)
--- a/libs/ardour/session_export.cc
+++ b/libs/ardour/session_export.cc
@@ -73,12 +73,16 @@ Session::pre_export ()
                }
        }
 
-       /* make sure we are actually rolling */
+       /* prepare transport */
+
+       realtime_stop (true, true);
 
        if (get_record_enabled()) {
                disable_record (false);
        }
 
+       unset_play_loop ();
+
        /* no slaving */
 
        post_export_sync = config.get_external_sync ();
@@ -87,9 +91,9 @@ Session::pre_export ()
        config.set_external_sync (false);
 
        _exporting = true;
-       export_status->running = true;
+       export_status->set_running (true);
        export_status->Finished.connect_same_thread (*this, boost::bind (&Session::finalize_audio_export, this));
-       
+
        /* disable MMC output early */
 
        _pre_export_mmc_enabled = _mmc->send_enabled ();
@@ -105,13 +109,14 @@ Session::start_audio_export (framepos_t position)
        if (!_exporting) {
                pre_export ();
        }
-       _export_started = false;
+
+       _export_preroll = 10.0 * nominal_frame_rate (); // TODO make configurable
 
        /* We're about to call Track::seek, so the butler must have finished everything
           up otherwise it could be doing do_refill in its thread while we are doing
           it here.
        */
-       
+
        _butler->wait_until_finished ();
 
        /* get everyone to the right position */
@@ -190,18 +195,29 @@ Session::process_export (pframes_t nframes)
 int
 Session::process_export_fw (pframes_t nframes)
 {
-       if (!_export_started) {
-               _export_started = true;
-               set_transport_speed (1.0, false);
+       if (_export_preroll > 0) {
+
+               _engine.main_thread()->get_buffers ();
+               fail_roll (nframes);
+               _engine.main_thread()->drop_buffers ();
+
+               _export_preroll -= std::min ((framepos_t)nframes, _export_preroll);
+
+               if (_export_preroll > 0) {
+                       // clear out buffers (reverb tails etc).
+                       return 0;
+               }
+
+               set_transport_speed (1.0, 0, false);
                butler_transport_work ();
                g_atomic_int_set (&_butler->should_do_transport_work, 0);
                post_transport ();
                return 0;
        }
-       
-        _engine.main_thread()->get_buffers ();
+
+       _engine.main_thread()->get_buffers ();
        process_export (nframes);
-        _engine.main_thread()->drop_buffers ();
+       _engine.main_thread()->drop_buffers ();
 
        return 0;
 }
@@ -235,7 +251,7 @@ Session::finalize_audio_export ()
        _engine.freewheel (false);
 
        export_freewheel_connection.disconnect();
-       
+
        _mmc->enable_send (_pre_export_mmc_enabled);
 
        /* maybe write CUE/TOC */