From 7392e8b619b282d896b89ecb69526f178c8812f3 Mon Sep 17 00:00:00 2001
From: Leland Lucius <github@homerow.net>
Date: Fri, 12 Feb 2021 08:06:59 -0600
Subject: [PATCH] Bug 621 - Metadata Editor: saved tags not displayed when
 importing MP2/MP3/FLAC/FFmpeg formats without metadata

---
 src/import/ImportFFmpeg.cpp | 31 +++++++++++++----------
 src/import/ImportFLAC.cpp   | 50 +++++++++++++++++++------------------
 src/import/ImportMP3.cpp    |  6 ++---
 3 files changed, 47 insertions(+), 40 deletions(-)

diff --git a/src/import/ImportFFmpeg.cpp b/src/import/ImportFFmpeg.cpp
index 774ff1cf4..6239768da 100644
--- a/src/import/ImportFFmpeg.cpp
+++ b/src/import/ImportFFmpeg.cpp
@@ -226,7 +226,7 @@ public:
    ///\ tags - Audacity tags object
    ///\ tag - name of tag to set
    ///\ name - name of metadata item to retrieve
-   void GetMetadata(Tags *tags, const wxChar *tag, const char *name);
+   void GetMetadata(Tags &tags, const wxChar *tag, const char *name);
 
    ///! Called by Import.cpp
    ///\return number of readable streams in the file
@@ -730,34 +730,39 @@ ProgressResult FFmpegImportFileHandle::WriteData(streamContext *sc)
 
 void FFmpegImportFileHandle::WriteMetadata(Tags *tags)
 {
-   tags->Clear();
+   Tags temp;
 
-   GetMetadata(tags, TAG_TITLE, "title");
-   GetMetadata(tags, TAG_COMMENTS, "comment");
-   GetMetadata(tags, TAG_ALBUM, "album");
-   GetMetadata(tags, TAG_TRACK, "track");
-   GetMetadata(tags, TAG_GENRE, "genre");
+   GetMetadata(temp, TAG_TITLE, "title");
+   GetMetadata(temp, TAG_COMMENTS, "comment");
+   GetMetadata(temp, TAG_ALBUM, "album");
+   GetMetadata(temp, TAG_TRACK, "track");
+   GetMetadata(temp, TAG_GENRE, "genre");
 
    if (wxString(mFormatContext->iformat->name).Contains("m4a"))
    {
-      GetMetadata(tags, TAG_ARTIST, "artist");
-      GetMetadata(tags, TAG_YEAR, "date");
+      GetMetadata(temp, TAG_ARTIST, "artist");
+      GetMetadata(temp, TAG_YEAR, "date");
    }
    else
    {
-      GetMetadata(tags, TAG_ARTIST, "author");
-      GetMetadata(tags, TAG_YEAR, "year");
+      GetMetadata(temp, TAG_ARTIST, "author");
+      GetMetadata(temp, TAG_YEAR, "year");
+   }
+
+   if (!temp.IsEmpty())
+   {
+      *tags = temp;
    }
 }
 
-void FFmpegImportFileHandle::GetMetadata(Tags *tags, const wxChar *tag, const char *name)
+void FFmpegImportFileHandle::GetMetadata(Tags &tags, const wxChar *tag, const char *name)
 {
    AVDictionaryEntry *meta;
 
    meta = av_dict_get(mFormatContext->metadata, name, NULL, AV_DICT_IGNORE_SUFFIX);
    if (meta)
    {
-      tags->SetTag(tag, wxString::FromUTF8(meta->value));
+      tags.SetTag(tag, wxString::FromUTF8(meta->value));
    }
 }
 
diff --git a/src/import/ImportFLAC.cpp b/src/import/ImportFLAC.cpp
index 50835daa9..1970b7f91 100644
--- a/src/import/ImportFLAC.cpp
+++ b/src/import/ImportFLAC.cpp
@@ -443,34 +443,36 @@ ProgressResult FLACImportFileHandle::Import(WaveTrackFactory *trackFactory,
    wxString comment;
    wxString description;
 
-   tags->Clear();
    size_t cnt = mFile->mComments.size();
-   for (size_t c = 0; c < cnt; c++) {
-      wxString name = mFile->mComments[c].BeforeFirst(wxT('='));
-      wxString value = mFile->mComments[c].AfterFirst(wxT('='));
-      wxString upper = name.Upper();
-      if (upper == wxT("DATE") && !tags->HasTag(TAG_YEAR)) {
-         long val;
-         if (value.length() == 4 && value.ToLong(&val)) {
-            name = TAG_YEAR;
+   if (cnt > 0) {
+      tags->Clear();
+      for (size_t c = 0; c < cnt; c++) {
+         wxString name = mFile->mComments[c].BeforeFirst(wxT('='));
+         wxString value = mFile->mComments[c].AfterFirst(wxT('='));
+         wxString upper = name.Upper();
+         if (upper == wxT("DATE") && !tags->HasTag(TAG_YEAR)) {
+            long val;
+            if (value.length() == 4 && value.ToLong(&val)) {
+               name = TAG_YEAR;
+            }
          }
+         else if (upper == wxT("COMMENT") || upper == wxT("COMMENTS")) {
+            comment = value;
+            continue;
+         }
+         else if (upper == wxT("DESCRIPTION")) {
+            description = value;
+            continue;
+         }
+         tags->SetTag(name, value);
       }
-      else if (upper == wxT("COMMENT") || upper == wxT("COMMENTS")) {
-         comment = value;
-         continue;
-      }
-      else if (upper == wxT("DESCRIPTION")) {
-         description = value;
-         continue;
-      }
-      tags->SetTag(name, value);
-   }
 
-   if (comment.empty()) {
-      comment = description;
-   }
-   if (!comment.empty()) {
-      tags->SetTag(TAG_COMMENTS, comment);
+      if (comment.empty()) {
+         comment = description;
+      }
+      if (!comment.empty()) {
+         tags->SetTag(TAG_COMMENTS, comment);
+      }
    }
 
    return mUpdateResult;
diff --git a/src/import/ImportMP3.cpp b/src/import/ImportMP3.cpp
index fdd95e1ce..8c2ca6b3c 100644
--- a/src/import/ImportMP3.cpp
+++ b/src/import/ImportMP3.cpp
@@ -661,8 +661,6 @@ bool MP3ImportFileHandle::FillBuffer()
 void MP3ImportFileHandle::LoadID3(Tags *tags)
 {
 #ifdef USE_LIBID3TAG
-   tags->Clear();
-
    struct id3_file *id3file = NULL;
    auto cleanup = finally([&]
    {
@@ -686,7 +684,7 @@ void MP3ImportFileHandle::LoadID3(Tags *tags)
 
    // Load the tags
    struct id3_tag *id3tags = id3_file_tag(id3file);
-   if (!id3tags)
+   if (!id3tags || id3tags->nframes == 0)
    {
       return;
    }
@@ -722,6 +720,8 @@ void MP3ImportFileHandle::LoadID3(Tags *tags)
       return wxString((char *) buf, converter);
    };
 
+   tags->Clear();
+
    // Extract tags from ID3 frames and add to our tags
    bool have_year = false;
    for (unsigned int i = 0; i < id3tags->nframes; ++i)