[multimedia/kwave/5-codec_mp3-broken-id3-tags-due-to-id3lib-bad-handling-of-utf-16] plugins/codec_mp3: codec_mp3: workaround for broken MBS conversion in ID3LIB

Git commit a98c47b39a936e844fa250673c7a871b8dfe9207 by Thomas Eschenbacher.
Committed on 15/08/2026 at 08:41.
Pushed by eschenbacher into branch '5-codec_mp3-broken-id3-tags-due-to-id3lib-bad-handling-of-utf-16'.

codec_mp3: workaround for broken MBS conversion in ID3LIB

M  +57   -6    plugins/codec_mp3/MP3Decoder.cpp
M  +6    -5    plugins/codec_mp3/MP3Encoder.cpp

https://invent.kde.org/multimedia/kwave/-/commit/a98c47b39a936e844fa250673c7a871b8dfe9207

diff --git a/plugins/codec_mp3/MP3Decoder.cpp b/plugins/codec_mp3/MP3Decoder.cpp
index ea56a1b4..74568685 100644
--- a/plugins/codec_mp3/MP3Decoder.cpp
+++ b/plugins/codec_mp3/MP3Decoder.cpp
@@ -32,6 +32,7 @@
 #include <QDateTime>
 #include <QIODevice>
 #include <QLatin1Char>
+#include <QStringView>
 #include <QTime>
 
 #include "libkwave/Compression.h"
@@ -416,13 +417,63 @@ bool Kwave::MP3Decoder::parseID3Tags(ID3_Tag &tag)
 //***************************************************************************
 QString Kwave::MP3Decoder::parseId3Frame2String(const ID3_Frame *frame)
 {
-    QString s;
-    char *text = ID3_GetString(frame, ID3FN_TEXT);
-    if (text && strlen(text)) {
-        s = _(text);
-        ID3_FreeString(text);
+    if (!frame) return QString();
+
+    // retrieve the encoding field from the ID3 frame
+    ID3_TextEnc enc = ID3TE_NONE;
+    const ID3_Field *enc_field = frame->GetField(ID3FN_TEXTENC);
+    if (enc_field != nullptr)
+        enc = static_cast<ID3_TextEnc>(enc_field->Get());
+
+    switch (enc) {
+        case ID3TE_UTF16: /* FALLTHROUGH */
+        case ID3TE_UTF16BE: {
+            // read raw unicode text directly to bypass id3lib's broken
+            // mbs conversion
+            const ID3_Field *field = frame->GetField(ID3FN_TEXT);
+            if (field != nullptr) {
+                const size_t num_chars = field->GetNumTextItems();
+                if (num_chars > 0) {
+                    const char16_t *uc16_data =
+                        reinterpret_cast<const char16_t *>(
+                            field->GetRawText());
+                    const size_t size_in_bytes = field->Size();
+                    if ((uc16_data != nullptr) && (size_in_bytes > 0)) {
+                        const size_t max_chars =
+                            size_in_bytes / sizeof(char16_t);
+                        const qsizetype pos =
+                            QStringView(uc16_data, max_chars).indexOf(u'\0');
+                        const qsizetype len = (pos >= 0) ? pos :
+                            static_cast<qsizetype>(max_chars);
+                        return QString::fromUtf16(uc16_data, len).trimmed();
+                    }
+                }
+            }
+            break;
+        }
+        case ID3TE_UTF8: {
+            char *text = ID3_GetString(frame, ID3FN_TEXT);
+            if (text != nullptr) {
+                QString result = QString::fromUtf8(text).trimmed();
+                ID3_FreeString(text);
+                return result;
+            }
+            break;
+        }
+        case ID3TE_ISO8859_1: /* FALLTHROUGH */
+        case ID3TE_NONE:      /* FALLTHROUGH */
+        default: {
+            char *text = ID3_GetString(frame, ID3FN_TEXT);
+            if (text != nullptr) {
+                QString result = QString::fromLatin1(text).trimmed();
+                ID3_FreeString(text);
+                return result;
+            }
+            break;
+        }
     }
-    return s;
+
+    return QString();
 }
 
 //***************************************************************************
diff --git a/plugins/codec_mp3/MP3Encoder.cpp b/plugins/codec_mp3/MP3Encoder.cpp
index 942ee845..77a681eb 100644
--- a/plugins/codec_mp3/MP3Encoder.cpp
+++ b/plugins/codec_mp3/MP3Encoder.cpp
@@ -90,7 +90,6 @@ void Kwave::MP3Encoder::encodeID3Tags(const Kwave::MetaDataList &meta_data,
                                       ID3_Tag &tag)
 {
     const Kwave::FileInfo info(meta_data);
-    ID3_FrameInfo frameInfo;
 
     const QMap<Kwave::FileProperty, QVariant> properties(info.properties());
     QMap<Kwave::FileProperty, QVariant>::const_iterator it;
@@ -134,7 +133,7 @@ void Kwave::MP3Encoder::encodeID3Tags(const Kwave::MetaDataList &meta_data,
             {
                 field->SetEncoding(ID3TE_UTF16);
 
-                // if "number of CDs is available: append with "/"
+                // if "number of CDs" is available: append with "/"
                 int cds = info.get(Kwave::INF_CDS).toInt();
                 if (cds > 0)
                     str_val += _("/%1").arg(cds);
@@ -144,7 +143,7 @@ void Kwave::MP3Encoder::encodeID3Tags(const Kwave::MetaDataList &meta_data,
             }
             case ID3_PropertyMap::ENC_TRACK_NUM:
             {
-                // if "number of tracks is available: append with "/"
+                // if "number of tracks" is available: append with "/"
                 int tracks = info.get(Kwave::INF_TRACKS).toInt();
                 if (tracks > 0)
                     str_val += _("/%1").arg(tracks);
@@ -179,8 +178,10 @@ void Kwave::MP3Encoder::encodeID3Tags(const Kwave::MetaDataList &meta_data,
                     }
                     /* frame->GetField(ID3FN_DESCRIPTION)->Set("..."); */
                     field = frame->GetField(ID3FN_TEXT);
-                    field->SetEncoding(ID3TE_UTF16);
-                    field->Set(static_cast<const unicode_t *>(c.utf16()));
+                    if (field) {
+                        field->SetEncoding(ID3TE_UTF16);
+                        field->Set(static_cast<const unicode_t *>(c.utf16()));
+                    }
 
                     if (tag.AttachFrame(frame)) {
                         frame = nullptr;