More expressive Audio- and MetadataSource interfaces

55 files changed, 1474 insertions, 1387 deletions

diff --git a/build/depends.py b/build/depends.py
index c2388e1e19..7553dd4f50 100644
--- a/build/depends.py
+++ b/build/depends.py
@@ -816,7 +816,7 @@ class MixxxCore(Feature):
 
                    "sources/audiosource.cpp",
                    "sources/audiosourcestereoproxy.cpp",
-                   "sources/metadatasource.cpp",
+                   "sources/metadatasourcetaglib.cpp",
                    "sources/soundsource.cpp",
                    "sources/soundsourceplugin.cpp",
                    "sources/soundsourcepluginlibrary.cpp",
diff --git a/plugins/soundsourcem4a/SConscript b/plugins/soundsourcem4a/SConscript
index a6cdc375c0..9e1a45f7e8 100644
--- a/plugins/soundsourcem4a/SConscript
+++ b/plugins/soundsourcem4a/SConscript
@@ -13,7 +13,7 @@ Import('build')
 m4a_sources = [
     "soundsourcem4a.cpp",
     "sources/audiosource.cpp",
-    "sources/metadatasource.cpp",
+    "sources/metadatasourcetaglib.cpp",
     "sources/soundsource.cpp",
     "sources/soundsourceplugin.cpp",
     "util/audiosignal.cpp",
diff --git a/plugins/soundsourcem4a/soundsourcem4a.cpp b/plugins/soundsourcem4a/soundsourcem4a.cpp
index 7b974f4ab3..49e2c82726 100644
--- a/plugins/soundsourcem4a/soundsourcem4a.cpp
+++ b/plugins/soundsourcem4a/soundsourcem4a.cpp
@@ -176,7 +176,7 @@ SoundSourceM4A::~SoundSourceM4A() {
 
 SoundSource::OpenResult SoundSourceM4A::tryOpen(
         OpenMode mode,
-        const AudioSourceConfig& audioSrcCfg) {
+        const OpenParams& params) {
     DEBUG_ASSERT(MP4_INVALID_FILE_HANDLE == m_hFile);
     // open MP4 file, check for >= ver 1.9.1
     // From mp4v2/file.h:
@@ -252,7 +252,7 @@ SoundSource::OpenResult SoundSourceM4A::tryOpen(
     }
     m_inputBuffer.resize(maxSampleBlockInputSize, 0);
 
-    m_audioSrcCfg = audioSrcCfg;
+    m_openParams = params;
 
     if (openDecoder()) {
         return OpenResult::Succeeded;
@@ -272,8 +272,8 @@ bool SoundSourceM4A::openDecoder() {
     NeAACDecConfigurationPtr pDecoderConfig = NeAACDecGetCurrentConfiguration(
             m_hDecoder);
     pDecoderConfig->outputFormat = FAAD_FMT_FLOAT;
-    if (m_audioSrcCfg.channelCount().isMono() ||
-            m_audioSrcCfg.channelCount().isStereo()) {
+    if (m_openParams.channelCount().isMono() ||
+            m_openParams.channelCount().isStereo()) {
         pDecoderConfig->downMatrix = 1;
     } else {
         pDecoderConfig->downMatrix = 0;
diff --git a/plugins/soundsourcem4a/soundsourcem4a.h b/plugins/soundsourcem4a/soundsourcem4a.h
index 858257a64b..0ef84a9ac5 100644
--- a/plugins/soundsourcem4a/soundsourcem4a.h
+++ b/plugins/soundsourcem4a/soundsourcem4a.h
@@ -31,7 +31,7 @@ class SoundSourceM4A: public SoundSourcePlugin {
   private:
     OpenResult tryOpen(
             OpenMode mode,
-            const AudioSourceConfig& audioSrcCfg) override;
+            const OpenParams& params) override;
 
     bool openDecoder();
     void closeDecoder();
@@ -51,7 +51,7 @@ class SoundSourceM4A: public SoundSourcePlugin {
     SINT m_inputBufferLength;
     SINT m_inputBufferOffset;
 
-    AudioSourceConfig m_audioSrcCfg;
+    OpenParams m_openParams;
 
     NeAACDecHandle m_hDecoder;
     SINT m_numberOfPrefetchSampleBlocks;
diff --git a/plugins/soundsourcemediafoundation/SConscript b/plugins/soundsourcemediafoundation/SConscript
index 3edd7a1362..21f9a55736 100644
--- a/plugins/soundsourcemediafoundation/SConscript
+++ b/plugins/soundsourcemediafoundation/SConscript
@@ -21,7 +21,7 @@ if int(build.flags['mediafoundation']):
     ssmediafoundation_bin = env.SharedLibrary('soundsourcemediafoundation',

         ['soundsourcemediafoundation.cpp',

          'sources/audiosource.cpp',

-         'sources/metadatasource.cpp',

+         'sources/metadatasourcetaglib.cpp',

          'sources/soundsource.cpp',

          'sources/soundsourceplugin.cpp',

          'util/audiosignal.cpp',

diff --git a/plugins/soundsourcemediafoundation/soundsourcemediafoundation.cpp b/plugins/soundsourcemediafoundation/soundsourcemediafoundation.cpp
index 637ed85dfa..78c370feed 100755
--- a/plugins/soundsourcemediafoundation/soundsourcemediafoundation.cpp
+++ b/plugins/soundsourcemediafoundation/soundsourcemediafoundation.cpp
@@ -55,7 +55,7 @@ SoundSourceMediaFoundation::~SoundSourceMediaFoundation() {
 
 SoundSource::OpenResult SoundSourceMediaFoundation::tryOpen(
         OpenMode /*mode*/,
-        const AudioSourceConfig& audioSrcCfg) {
+        const OpenParams& params) {
     VERIFY_OR_DEBUG_ASSERT(!SUCCEEDED(m_hrCoInitialize)) {
         kLogger.warning()
                 << "Cannot reopen file"
@@ -98,7 +98,7 @@ SoundSource::OpenResult SoundSourceMediaFoundation::tryOpen(
         return OpenResult::Failed;
     }
 
-    if (!configureAudioStream(audioSrcCfg)) {
+    if (!configureAudioStream(config)) {
         kLogger.warning()
                 << "Failed to configure audio stream";
         return OpenResult::Failed;
@@ -485,7 +485,7 @@ ReadableSampleFrames SoundSourceMediaFoundation::readSampleFramesClamped(
  If anything in here fails, just bail. I'm not going to decode HRESULTS.
  -- Bill
  */
-bool SoundSourceMediaFoundation::configureAudioStream(const AudioSourceConfig& audioSrcCfg) {
+bool SoundSourceMediaFoundation::configureAudioStream(const OpenParams& params) {
     HRESULT hr;
 
     // deselect all streams, we only want the first
@@ -591,8 +591,8 @@ bool SoundSourceMediaFoundation::configureAudioStream(const AudioSourceConfig& a
     } else {
         qDebug() << "Number of channels in input stream" << numChannels;
     }
-    if (audioSrcCfg.channelCount().valid()) {
-        numChannels = audioSrcCfg.channelCount();
+    if (params.channelCount().valid()) {
+        numChannels = params.channelCount();
         hr = pAudioType->SetUINT32(
                 MF_MT_AUDIO_NUM_CHANNELS, numChannels);
         if (FAILED(hr)) {
@@ -615,8 +615,8 @@ bool SoundSourceMediaFoundation::configureAudioStream(const AudioSourceConfig& a
     } else {
         qDebug() << "Samples per second in input stream" << samplesPerSecond;
     }
-    if (audioSrcCfg.samplingRate().valid()) {
-        samplesPerSecond = audioSrcCfg.samplingRate();
+    if (params.samplingRate().valid()) {
+        samplesPerSecond = params.samplingRate();
         hr = pAudioType->SetUINT32(
                 MF_MT_AUDIO_SAMPLES_PER_SECOND, samplesPerSecond);
         if (FAILED(hr)) {
diff --git a/plugins/soundsourcemediafoundation/soundsourcemediafoundation.h b/plugins/soundsourcemediafoundation/soundsourcemediafoundation.h
index 19c7a99b3f..27f4f3b41f 100755
--- a/plugins/soundsourcemediafoundation/soundsourcemediafoundation.h
+++ b/plugins/soundsourcemediafoundation/soundsourcemediafoundation.h
@@ -64,9 +64,9 @@ class SoundSourceMediaFoundation: public mixxx::SoundSourcePlugin {
   private:
     OpenResult tryOpen(
             OpenMode mode,
-            const mixxx::AudioSourceConfig& audioSrcCfg) override;
+            const mixxx::AudioSource::OpenParams& params) override;
 
-    bool configureAudioStream(const mixxx::AudioSourceConfig& audioSrcCfg);
+    bool configureAudioStream(const mixxx::AudioSource::OpenParams& params);
     bool readProperties();
 
     void seekSampleFrame(SINT frameIndex);
diff --git a/plugins/soundsourcewv/SConscript b/plugins/soundsourcewv/SConscript
index 2f25d23bd5..bf3a712e88 100644
--- a/plugins/soundsourcewv/SConscript
+++ b/plugins/soundsourcewv/SConscript
@@ -13,7 +13,7 @@ Import('build')
 wv_sources = [
     "soundsourcewv.cpp",
     "sources/audiosource.cpp",
-    "sources/metadatasource.cpp",
+    "sources/metadatasourcetaglib.cpp",
     "sources/soundsource.cpp",
     "sources/soundsourceplugin.cpp",
     "util/audiosignal.cpp",
diff --git a/plugins/soundsourcewv/soundsourcewv.cpp b/plugins/soundsourcewv/soundsourcewv.cpp
index f1e006fd8e..734b6556a8 100644
--- a/plugins/soundsourcewv/soundsourcewv.cpp
+++ b/plugins/soundsourcewv/soundsourcewv.cpp
@@ -39,12 +39,12 @@ SoundSourceWV::~SoundSourceWV() {
 
 SoundSource::OpenResult SoundSourceWV::tryOpen(
         OpenMode /*mode*/,
-        const AudioSourceConfig& audioSrcCfg) {
+        const OpenParams& params) {
     DEBUG_ASSERT(!m_wpc);
     char msg[80]; // hold possible error message
     int openFlags = OPEN_WVC | OPEN_NORMALIZE;
-    if (audioSrcCfg.channelCount().isMono() ||
-            audioSrcCfg.channelCount().isStereo()) {
+    if (params.channelCount().isMono() ||
+            params.channelCount().isStereo()) {
         openFlags |= OPEN_2CH_MAX;
     }
 
diff --git a/plugins/soundsourcewv/soundsourcewv.h b/plugins/soundsourcewv/soundsourcewv.h
index 23866b6390..7ce6f340b6 100644
--- a/plugins/soundsourcewv/soundsourcewv.h
+++ b/plugins/soundsourcewv/soundsourcewv.h
@@ -23,7 +23,7 @@ class SoundSourceWV: public SoundSourcePlugin {
   private:
     OpenResult tryOpen(
             OpenMode mode,
-            const AudioSourceConfig& audioSrcCfg) override;
+            const OpenParams& params) override;
 
     static int32_t ReadBytesCallback(void* id, void* data, int bcount);
     static uint32_t GetPosCallback(void* id);
diff --git a/src/analyzer/analyzerqueue.cpp b/src/analyzer/analyzerqueue.cpp
index 47ac7a0e9d..eea8d5c0e8 100644
--- a/src/analyzer/analyzerqueue.cpp
+++ b/src/analyzer/analyzerqueue.cpp
@@ -342,9 +342,9 @@ void AnalyzerQueue::execThread() {
         Trace trace("AnalyzerQueue analyzing track");
 
         // Get the audio
-        mixxx::AudioSourceConfig audioSrcCfg;
-        audioSrcCfg.setChannelCount(kAnalysisChannels);
-        auto pAudioSource = SoundSourceProxy(nextTrack).openAudioSource(audioSrcCfg);
+        mixxx::AudioSource::OpenParams openParams;
+        openParams.setChannelCount(kAnalysisChannels);
+        auto pAudioSource = SoundSourceProxy(nextTrack).openAudioSource(openParams);
         if (!pAudioSource) {
             kLogger.warning()
                     << "Failed to open file for analyzing:"
diff --git a/src/engine/cachingreaderworker.cpp b/src/engine/cachingreaderworker.cpp
index ca98ea82a4..8294be4ccb 100644
--- a/src/engine/cachingreaderworker.cpp
+++ b/src/engine/cachingreaderworker.cpp
@@ -118,8 +118,8 @@ void CachingReaderWorker::run() {
 
 namespace {
 
-mixxx::AudioSourcePointer openAudioSourceForReading(const TrackPointer& pTrack, const mixxx::AudioSourceConfig& audioSrcCfg) {
-    auto pAudioSource = SoundSourceProxy(pTrack).openAudioSource(audioSrcCfg);
+mixxx::AudioSourcePointer openAudioSourceForReading(const TrackPointer& pTrack, const mixxx::AudioSource::OpenParams& params) {
+    auto pAudioSource = SoundSourceProxy(pTrack).openAudioSource(params);
     if (!pAudioSource) {
         kLogger.warning() << "Failed to open file:" << pTrack->getLocation();
     }
@@ -155,9 +155,9 @@ void CachingReaderWorker::loadTrack(const TrackPointer& pTrack) {
         return;
     }
 
-    mixxx::AudioSourceConfig audioSrcCfg;
-    audioSrcCfg.setChannelCount(CachingReaderChunk::kChannels);
-    m_pAudioSource = openAudioSourceForReading(pTrack, audioSrcCfg);
+    mixxx::AudioSource::OpenParams config;
+    config.setChannelCount(CachingReaderChunk::kChannels);
+    m_pAudioSource = openAudioSourceForReading(pTrack, config);
     if (!m_pAudioSource) {
         m_readableFrameIndexRange = mixxx::IndexRange();
         // Must unlock before emitting to avoid deadlock
diff --git a/src/library/browse/browsetablemodel.cpp b/src/library/browse/browsetablemodel.cpp
index 1ae4f3ffe6..b5f208dbe4 100644
--- a/src/library/browse/browsetablemodel.cpp
+++ b/src/library/browse/browsetablemodel.cpp
@@ -11,7 +11,7 @@
 #include "mixer/playerinfo.h"
 #include "control/controlobject.h"
 #include "library/dao/trackdao.h"
-#include "track/trackmetadatataglib.h"
+#include "sources/metadatasourcetaglib.h"
 #include "util/dnd.h"
 
 BrowseTableModel::BrowseTableModel(QObject* parent,
@@ -318,7 +318,8 @@ bool BrowseTableModel::setData(const QModelIndex &index, const QVariant &value,
 
     QStandardItem* item = itemFromIndex(index);
     QString track_location(getTrackLocation(index));
-    if (OK == mixxx::taglib::writeTrackMetadataIntoFile(trackMetadata, track_location)) {
+    if (mixxx::MetadataSource::ExportResult::Succeeded ==
+            mixxx::MetadataSourceTagLib(track_location).exportTrackMetadata(trackMetadata)) {
         // Modify underlying interalPointer object
         item->setText(value.toString());
         item->setToolTip(item->text());
diff --git a/src/library/coverartutils.cpp b/src/library/coverartutils.cpp
index 654132697f..336aba9a24 100644
--- a/src/library/coverartutils.cpp
+++ b/src/library/coverartutils.cpp
@@ -38,7 +38,7 @@ QImage CoverArtUtils::extractEmbeddedCover(
         const QFileInfo& fileInfo,
         SecurityTokenPointer pToken) {
     auto pTrack = Track::newTemporary(fileInfo, pToken);
-    return SoundSourceProxy(pTrack).parseCoverImage();
+    return SoundSourceProxy(pTrack).importCoverImage();
 }
 
 //static
diff --git a/src/library/dao/trackdao.cpp b/src/library/dao/trackdao.cpp
index 673025112c..0df8d5e8d6 100644
--- a/src/library/dao/trackdao.cpp
+++ b/src/library/dao/trackdao.cpp
@@ -281,7 +281,7 @@ void TrackDAO::saveTrack(Track* pTrack) {
         // could alternatively store a second copy of TrackMetadata
         // in Track.
         if (m_pConfig && m_pConfig->getValueString(ConfigKey("[Library]","WriteAudioTags")).toInt() == 1) {
-            SoundSourceProxy::saveTrackMetadata(pTrack);
+            SoundSourceProxy::exportTrackMetadata(pTrack);
         }
     }
 }
@@ -1404,7 +1404,7 @@ TrackPointer TrackDAO::getTrackFromDB(TrackId trackId) const {
                 " to replace the default value introduced with a previous"
                 " schema upgrade";
         mixxx::TrackMetadata trackMetadata;
-        if (SoundSourceProxy(pTrack).parseTrackMetadata(&trackMetadata) == OK) {
+        if (SoundSourceProxy(pTrack).importTrackMetadata(&trackMetadata) == mixxx::MetadataSource::ImportResult::Succeeded) {
             // Copy the track total from the temporary track object
             pTrack->setTrackTotal(trackMetadata.getTrackTotal());
             // Also set the track number if it is still empty due
diff --git a/src/musicbrainz/chromaprinter.cpp b/src/musicbrainz/chromaprinter.cpp
index 58a465efc7..917ce1e9ca 100644
--- a/src/musicbrainz/chromaprinter.cpp
+++ b/src/musicbrainz/chromaprinter.cpp
@@ -119,9 +119,9 @@ ChromaPrinter::ChromaPrinter(QObject* parent)
 }
 
 QString ChromaPrinter::getFingerprint(TrackPointer pTrack) {
-    mixxx::AudioSourceConfig audioSrcCfg;
-    audioSrcCfg.setChannelCount(kFingerprintChannels);
-    auto pAudioSource = SoundSourceProxy(pTrack).openAudioSource(audioSrcCfg);
+    mixxx::AudioSource::OpenParams config;
+    config.setChannelCount(kFingerprintChannels);
+    auto pAudioSource = SoundSourceProxy(pTrack).openAudioSource(config);
     if (!pAudioSource || (pAudioSource->channelCount() != kFingerprintChannels)) {
         qDebug()
                 << "Failed to open file for fingerprinting"
diff --git a/src/sources/audiosource.cpp b/src/sources/audiosource.cpp
index ded3e13950..a21067a586 100644
--- a/src/sources/audiosource.cpp
+++ b/src/sources/audiosource.cpp
@@ -16,9 +16,30 @@ AudioSource::AudioSource(QUrl url)
           AudioSignal(kSampleLayout) {
 }
 
+AudioSource::OpenResult AudioSource::open(
+        OpenMode mode,
+        const OpenParams& params) {
+    close(); // reopening is not supported
+
+    OpenResult result;
+    try {
+        result = tryOpen(mode, params);
+    } catch (const std::exception& e) {
+        qWarning() << "Caught unexpected exception from SoundSource::tryOpen():" << e.what();
+        result = OpenResult::Failed;
+    } catch (...) {
+        qWarning() << "Caught unknown exception from SoundSource::tryOpen()";
+        result = OpenResult::Failed;
+    }
+    if (OpenResult::Succeeded != result) {
+        close(); // rollback
+    }
+    return result;
+}
+
 bool AudioSource::initFrameIndexRangeOnce(
         IndexRange frameIndexRange) {
-    VERIFY_OR_DEBUG_ASSERT(frameIndexRange.orientation() != mixxx::IndexRange::Orientation::Backward) {
+    VERIFY_OR_DEBUG_ASSERT(frameIndexRange.orientation() != IndexRange::Orientation::Backward) {
         kLogger.warning()
                 << "Backward frame index range not supported"
                 << frameIndexRange;
diff --git a/src/sources/audiosource.h b/src/sources/audiosource.h
index 59a5673da6..453eea5980 100644
--- a/src/sources/audiosource.h
+++ b/src/sources/audiosource.h
@@ -77,39 +77,6 @@ class WritableSampleFrames: public SampleFrames {
 };
 
 
-// Interface for reading audio data in sample frames.
-//
-// Each new type of source must implement at least readSampleFramesClamped().
-class /*interface*/ IAudioSource {
-  public:
-    virtual ~IAudioSource() = default;
-
-  protected:
-    // Reads as much of the the requested sample frames and writes
-    // them into the provided buffer. The capacity of the buffer
-    // and the requested range have already been checked and
-    // adjusted (= clamped) before if necessary.
-    //
-    // Returns the number of and decoded sample frames in a readable
-    // buffer. The returned buffer is just a view/slice of the provided
-    // writable buffer if the result is not empty. If the result is
-    // empty the internal memory pointer of the returned buffer might
-    // be null.
-    virtual ReadableSampleFrames readSampleFramesClamped(
-            WritableSampleFrames sampleFrames) = 0;
-
-    // The following function is required for accessing the protected
-    // read function from siblings implementing this interface, e.g.
-    // for proxies and adapters.
-    static ReadableSampleFrames readSampleFramesClampedOn(
-            IAudioSource& that,
-            WritableSampleFrames sampleFrames) {
-        return that.readSampleFramesClamped(sampleFrames);
-    }
-
-};
-
-
 // Common base class for audio sources.
 //
 // Both the number of channels and the sampling rate must
@@ -120,7 +87,7 @@ class /*interface*/ IAudioSource {
 //
 // Audio sources are implicitly opened upon creation and
 // closed upon destruction.
-class AudioSource: public UrlResource, public AudioSignal, public virtual /*interface*/ IAudioSource {
+class AudioSource: public UrlResource, public AudioSignal {
   public:
     virtual ~AudioSource() = default;
 
@@ -135,6 +102,70 @@ class AudioSource: public UrlResource, public AudioSignal, public virtual /*inte
     static constexpr SampleLayout kSampleLayout = SampleLayout::Interleaved;
 
 
+    enum class OpenMode {
+        // In Strict mode the opening operation should be aborted
+        // as soon as any inconsistencies are detected.
+        Strict,
+        // Opening in Permissive mode is used only after opening
+        // in Strict mode has been aborted by all available
+        // SoundSource implementations.
+        Permissive,
+    };
+
+    enum class OpenResult {
+        Succeeded,
+        // If a SoundSource is not able to open a file because of
+        // internal errors of if the format of the content is not
+        // supported it should return Aborted. This gives SoundSources
+        // with a lower priority the chance to open the same file.
+        // Example: A SoundSourceProvider has been registered for
+        // files with a certain extension, but the corresponding
+        // SoundSource does only support a subset of all possible
+        // data formats that might be stored in files with this
+        // extension.
+        Aborted,
+        // If a SoundSource return Failed while opening a file
+        // the entire operation will fail immediately. No other
+        // sources with lower priority will be given the chance
+        // to open the same file.
+        Failed,
+    };
+
+    // Parameters for opening audio sources
+    class OpenParams : public AudioSignal {
+      public:
+        OpenParams()
+            : AudioSignal(kSampleLayout) {
+        }
+        OpenParams(ChannelCount channelCount, SamplingRate samplingRate)
+            : AudioSignal(kSampleLayout, channelCount, samplingRate) {
+        }
+
+        using AudioSignal::setChannelCount;
+        using AudioSignal::setSamplingRate;
+    };
+
+    // Opens the AudioSource for reading audio data.
+    //
+    // Since reopening is not supported close() will be called
+    // implicitly before the AudioSource is actually opened.
+    //
+    // Optionally the caller may provide the desired properties of
+    // the decoded audio signal. Some decoders are able to reduce
+    // the number of channels or do resampling efficiently on the
+    // fly while decoding the input data.
+    OpenResult open(
+            OpenMode mode,
+            const OpenParams& params = OpenParams());
+
+
+    // Closes the AudioSource and frees all resources.
+    //
+    // Might be called even if the AudioSource has never been
+    // opened, has already been closed, or if opening has failed.
+    virtual void close() = 0;
+
+
     // The total length of audio data is bounded and measured in frames.
     IndexRange frameIndexRange() const {
         return m_frameIndexRange;
@@ -233,6 +264,53 @@ class AudioSource: public UrlResource, public AudioSignal, public virtual /*inte
         return initBitrateOnce(Bitrate(bitrate));
     }
 
+    // Tries to open the AudioSource for reading audio data according
+    // to the "Template Method" design pattern.
+    //
+    // The invocation of tryOpen() is enclosed in invocations of close():
+    //   - Before: Always
+    //   - After: Upon failure
+    // If tryOpen() throws an exception or returns a result other than
+    // OpenResult::Succeeded an invocation of close() will follow.
+    // Implementations do not need to free internal resources twice in
+    // both tryOpen() upon failure and close(). All internal resources
+    // should be freed in close() instead.
+    //
+    // Exceptions s