Merge pull request #470 from atsampson/sclocked

Initial support for subcarrier-locked sampling.
happycube · Mar 8, 2020 · 0c641fc · 0c641fc
2 parents 8954a19 + 3736ab0
commit 0c641fc
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Showing 4 changed files with 23 additions and 1 deletion.
diff --git a/tools/ld-chroma-decoder/encoder/palencoder.cpp b/tools/ld-chroma-decoder/encoder/palencoder.cpp
@@ -54,6 +54,7 @@ PALEncoder::PALEncoder(QFile &_rgbFile, QFile &_tbcFile, LdDecodeMetaData &_meta
     // Initialise video parameters based on ld-decode's usual output.
     // numberOfSequentialFields will be computed automatically.
     videoParameters.isSourcePal = true;
+    videoParameters.isSubcarrierLocked = false;
     videoParameters.colourBurstStart = 98;
     videoParameters.colourBurstEnd = 138;
     videoParameters.activeVideoStart = 185;

diff --git a/tools/ld-chroma-decoder/sourcefield.cpp b/tools/ld-chroma-decoder/sourcefield.cpp
@@ -31,6 +31,8 @@ void SourceField::loadFields(SourceVideo &sourceVideo, LdDecodeMetaData &ldDecod
                              qint32 lookBehindFrames, qint32 lookAheadFrames,
                              QVector<SourceField> &fields, qint32 &startIndex, qint32 &endIndex)
 {
+    const LdDecodeMetaData::VideoParameters &videoParameters = ldDecodeMetaData.getVideoParameters();
+
     // Work out indexes.
     // fields will contain {lookbehind fields... [startIndex] real fields... [endIndex] lookahead fields...}.
     startIndex = 2 * lookBehindFrames;
@@ -54,15 +56,31 @@ void SourceField::loadFields(SourceVideo &sourceVideo, LdDecodeMetaData &ldDecod
         fields[i].field = ldDecodeMetaData.getField(firstFieldNumber);
         fields[i + 1].field = ldDecodeMetaData.getField(secondFieldNumber);
 
+        const quint16 black = videoParameters.black16bIre;
+
         if (useBlankFrame) {
             // Fill both fields with black
-            const quint16 black = ldDecodeMetaData.getVideoParameters().black16bIre;
             fields[i].data.fill(black, sourceVideo.getFieldLength());
             fields[i + 1].data.fill(black, sourceVideo.getFieldLength());
         } else {
             // Fetch the input fields
             fields[i].data = sourceVideo.getVideoField(firstFieldNumber);
             fields[i + 1].data = sourceVideo.getVideoField(secondFieldNumber);
+
+            if (videoParameters.isSourcePal && videoParameters.isSubcarrierLocked) {
+                // With subcarrier-locked 4fSC PAL sampling, we have four
+                // "extra" samples over the course of the frame, so the two
+                // fields will be horizontally misaligned by two samples. Shift
+                // the second field to the left to compensate.
+                //
+                // XXX This should be done elsewhere, as it affects other tools
+                // too.
+
+                fields[i + 1].data.remove(0, 2);
+                for (int j = 0; j < 2; j++) {
+                    fields[i + 1].data.append(black);
+                }
+            }
         }
 
         frameNumber++;

diff --git a/tools/library/tbc/lddecodemetadata.cpp b/tools/library/tbc/lddecodemetadata.cpp
@@ -71,6 +71,7 @@ LdDecodeMetaData::VideoParameters LdDecodeMetaData::getVideoParameters()
     if (json.size({"videoParameters"}) > 0) {
         videoParameters.numberOfSequentialFields = json.value({"videoParameters", "numberOfSequentialFields"}).toInt();
         videoParameters.isSourcePal = json.value({"videoParameters", "isSourcePal"}).toBool();
+        videoParameters.isSubcarrierLocked = json.value({"videoParameters", "isSubcarrierLocked"}).toBool();
 
         videoParameters.colourBurstStart = json.value({"videoParameters", "colourBurstStart"}).toInt();
         videoParameters.colourBurstEnd = json.value({"videoParameters", "colourBurstEnd"}).toInt();
@@ -121,6 +122,7 @@ void LdDecodeMetaData::setVideoParameters (LdDecodeMetaData::VideoParameters _vi
     // Write the video parameters
     json.setValue({"videoParameters", "numberOfSequentialFields"}, getNumberOfFields());
     json.setValue({"videoParameters", "isSourcePal"}, _videoParameters.isSourcePal);
+    json.setValue({"videoParameters", "isSubcarrierLocked"}, _videoParameters.isSubcarrierLocked);
 
     json.setValue({"videoParameters", "colourBurstStart"}, _videoParameters.colourBurstStart);
     json.setValue({"videoParameters", "colourBurstEnd"}, _videoParameters.colourBurstEnd);

diff --git a/tools/library/tbc/lddecodemetadata.h b/tools/library/tbc/lddecodemetadata.h
@@ -50,6 +50,7 @@ class LdDecodeMetaData
         qint32 numberOfSequentialFields;
 
         bool isSourcePal;
+        bool isSubcarrierLocked;
 
         qint32 colourBurstStart;
         qint32 colourBurstEnd;