From 835abd9be382d848b1a8aa701c05e147571a017f Mon Sep 17 00:00:00 2001
From: Steve Daulton <stevedaulton@gmail.com>
Date: Sun, 12 Aug 2018 19:14:21 +0100
Subject: [PATCH] bug 1885 Linux: Allow retries when opening capture

On launch, Audacity scanning the sound system causes Pulse to grab
exclusive control of the audio device, causing the device to be
unavailable until Pulse times out and releases it.

If an attempt is made to start recording from the hardware device (hw:)
immediately after launch, PortAudio will time out before the device is
released. In this case we need to retry opening the capture stream.

(This also applies to monitoring).
---
 src/AudioIO.cpp | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index 4d89046c0..31d21e615 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -408,6 +408,7 @@ TimeTrack and AudioIOListener and whether the playback is looped.
 #include "Experimental.h"
 #include "AudioIO.h"
 #include "float_cast.h"
+#include "UndoManager.h"
 
 #include <cfloat>
 #include <math.h>
@@ -1779,12 +1780,27 @@ bool AudioIO::StartPortAudioStream(double sampleRate,
    int  userData = 24;
    int* lpUserData = (captureFormat_saved == int24Sample) ? &userData : NULL;
 
-   mLastPaError = Pa_OpenStream( &mPortStreamV19,
-                                 useCapture ? &captureParameters : NULL,
-                                 usePlayback ? &playbackParameters : NULL,
-                                 mRate, paFramesPerBufferUnspecified,
-                                 paNoFlag,
-                                 audacityAudioCallback, lpUserData );
+   // (Linux, bug 1885) On first use, the device may not be ready in time, so allow retries.
+   // On my test machine, no more than 3 attempts are required.
+   unsigned int maxTries = 1;
+#ifdef __WXGTK__
+   if (!mOwningProject->GetUndoManager()->UnsavedChanges())
+      maxTries = 5;
+#endif
+
+   for (unsigned int tries = 0; tries < maxTries; tries++) {
+      mLastPaError = Pa_OpenStream( &mPortStreamV19,
+                                    useCapture ? &captureParameters : NULL,
+                                    usePlayback ? &playbackParameters : NULL,
+                                    mRate, paFramesPerBufferUnspecified,
+                                    paNoFlag,
+                                    audacityAudioCallback, lpUserData );
+      if (mLastPaError == paNoError) {
+         break;
+      }
+      wxLogDebug("Attempt %u to open capture stream failed with: %d", 1 + tries, mLastPaError);
+      wxMilliSleep(1000);
+   }
 
 
 #if USE_PORTMIXER
@@ -1852,8 +1868,12 @@ void AudioIO::StartMonitoring(double sampleRate)
    success = StartPortAudioStream(sampleRate, (unsigned int)playbackChannels,
                                   (unsigned int)captureChannels,
                                   captureFormat);
-   // TODO: Check return value of success.
-   (void)success;
+
+   if (!success) {
+      wxString msg = wxString::Format(_("Error opening recording device.\nError code: %s"), gAudioIO->LastPaErrorString());
+      ShowErrorDialog(mOwningProject, _("Error"), msg, wxT("Error_opening_sound_device"));
+      return;
+   }
 
    wxCommandEvent e(EVT_AUDIOIO_MONITOR);
    e.SetEventObject(mOwningProject);