[multimedia/kwave] /: codec_flac: parallelized decoding + added check for > 8 channels

Git commit 8702df3ebdb946a7d36b7c057a9c90993b525597 by Thomas Eschenbacher.
Committed on 18/08/2026 at 14:31.
Pushed by eschenbacher into branch 'master'.

codec_flac: parallelized decoding + added check for > 8 channels

M  +2    -1    CHANGES
M  +28   -17   plugins/codec_flac/FlacDecoder.cpp
M  +7    -0    plugins/codec_flac/FlacEncoder.cpp
M  +2    -0    plugins/codec_ogg/OpusDecoder.cpp
M  +1    -1    plugins/codec_ogg/VorbisEncoder.cpp

https://invent.kde.org/multimedia/kwave/-/commit/8702df3ebdb946a7d36b7c057a9c90993b525597

diff --git a/CHANGES b/CHANGES
index d1ef8093..ae964744 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,5 @@
-26.11.70 [2026-08-17]
+26.11.70 [2026-08-18]
+ * codec_flac: parallelized decoding + added check for > 8 channels
  * codec_mp3: workaround for broken MBS conversion in ID3LIB
  * codec_mp3: do no longer explicitly link against libstdc++ and libz
  * codec_ogg: parallelized decoding of ogg/opus and ogg/vorbis
diff --git a/plugins/codec_flac/FlacDecoder.cpp b/plugins/codec_flac/FlacDecoder.cpp
index 77f315cd..3060924e 100644
--- a/plugins/codec_flac/FlacDecoder.cpp
+++ b/plugins/codec_flac/FlacDecoder.cpp
@@ -20,7 +20,9 @@
 #include <new>
 
 #include <QDateTime>
+#include <QFutureSynchronizer>
 #include <QIODevice>
+#include <QtConcurrentRun>
 
 #include <KLocalizedString>
 
@@ -109,31 +111,40 @@ Kwave::Decoder *Kwave::FlacDecoder::instance()
     if (shift < 0) shift = 0;
     unsigned int mul = (1 << shift);
 
-    // decode the samples into a temporary buffer and
-    // flush it to the Writer(s), track by track
-    for (unsigned int track=0; track < tracks; track++) {
+    QFutureSynchronizer<void> synchronizer;
+    for (unsigned int track = 0; track < tracks; ++track) {
         Kwave::Writer *writer = (*m_dest)[track];
-        Q_ASSERT(writer);
         if (!writer) continue;
-        const FLAC__int32 *src = buffer[track];
-        sample_t *d = dst.data();
 
-        for (unsigned int sample = 0; sample < samples; sample++) {
-            // the following cast is only necessary if
-            // sample_t is not equal to a quint32
-            sample_t s  = static_cast<sample_t>(*src++);
+        const FLAC__int32 *buf = buffer[track];
 
-            // correct precision
-            if (shift) s *= mul;
+        synchronizer.addFuture(QtConcurrent::run(
+            [buf, samples, shift, mul, writer]() {
+                Kwave::SampleArray dst(samples);
+                sample_t *d = dst.data();
+                const FLAC__int32 *src = buf;
 
-            // write to destination buffer
-            *d++ = s;
-        }
+                for (unsigned int sample = 0; sample < samples; ++sample) {
+                    // the following cast is only necessary if
+                    // sample_t is not equal to a quint32
+                    sample_t s = static_cast<sample_t>(*src++);
+
+                    // correct precision
+                    if (shift) s *= mul;
 
-        // flush the temporary buffer
-        (*writer) << dst;
+                    // write to destination buffer
+                    *d++ = s;
+                }
+
+                // write converted samples to destination track
+                (*writer) << dst;
+            }
+        ));
     }
 
+    // wait for all channels in this frame to complete
+    synchronizer.waitForFinished();
+
     // at this point we check for a user-cancel
     return (m_dest->isCanceled()) ?
         FLAC__STREAM_DECODER_WRITE_STATUS_ABORT :
diff --git a/plugins/codec_flac/FlacEncoder.cpp b/plugins/codec_flac/FlacEncoder.cpp
index 8812e6c8..20d1274e 100644
--- a/plugins/codec_flac/FlacEncoder.cpp
+++ b/plugins/codec_flac/FlacEncoder.cpp
@@ -183,6 +183,13 @@ bool Kwave::FlacEncoder::encode(QWidget *widget,
     unsigned int   bits   = info.bits();
     sample_index_t length = info.length();
 
+    if ((tracks == 0) || (tracks > 8)) {
+        Kwave::MessageBox::sorry(widget,
+            i18n("This codec supports only 1 ... 8 channels, "
+                 "%1 channels are not supported.", tracks));
+        return false;
+    }
+
     set_compression_level(5); // @todo make the FLAC compression configurable
     set_channels(static_cast<unsigned>(tracks));
     set_bits_per_sample(static_cast<unsigned>(bits));
diff --git a/plugins/codec_ogg/OpusDecoder.cpp b/plugins/codec_ogg/OpusDecoder.cpp
index 2651f62d..60554f71 100644
--- a/plugins/codec_ogg/OpusDecoder.cpp
+++ b/plugins/codec_ogg/OpusDecoder.cpp
@@ -26,8 +26,10 @@
 
 #include <QApplication>
 #include <QDate>
+#include <QFutureSynchronizer>
 #include <QIODevice>
 #include <QString>
+#include <QtConcurrentRun>
 #include <QtEndian>
 
 #include <KLocalizedString>
diff --git a/plugins/codec_ogg/VorbisEncoder.cpp b/plugins/codec_ogg/VorbisEncoder.cpp
index c1e8cf2e..65f6cd49 100644
--- a/plugins/codec_ogg/VorbisEncoder.cpp
+++ b/plugins/codec_ogg/VorbisEncoder.cpp
@@ -101,7 +101,7 @@ bool Kwave::VorbisEncoder::open(QWidget *widget, const Kwave::FileInfo &info,
     long int sample_rate = static_cast<long int>(info.rate());
     int default_bitrate = (DEFAULT_BITRATE / 2) * tracks;
 
-    if ((tracks ==0) || (tracks > 255)) {
+    if ((tracks == 0) || (tracks > 255)) {
         Kwave::MessageBox::sorry(widget,
             i18n("This codec supports only 1 ... 255 channels, "
                  "%1 channels are not supported.", tracks));