Clip XLL samples by default.

Even though XLL encoder is expected to handle all clipping issues, there
are XLL streams where decoded samples overflow indicated storage bit
depth after downmix reversal.

To work around this issue, always clip XLL samples unless DONT_CLIP
context flag was set by the user.

dcadec.c

@@ -179,7 +179,7 @@ static void signal_handler(int sig)
 
 int main(int argc, char **argv)
 {
-    int flags = DCADEC_FLAG_STRICT;
+    int flags = DCADEC_FLAG_STRICT | DCADEC_FLAG_DONT_CLIP;
     int wave_flags = 0;
     bool parse_only = false;
     bool no_progress = false;
@@ -191,9 +191,11 @@ int main(int argc, char **argv)
         switch (opt) {
         case '2':
             flags |= DCADEC_FLAG_KEEP_DMIX_2CH;
+            flags &= ~DCADEC_FLAG_DONT_CLIP;
             break;
         case '6':
             flags |= DCADEC_FLAG_KEEP_DMIX_6CH;
+            flags &= ~DCADEC_FLAG_DONT_CLIP;
             break;
         case 'b':
             flags |= DCADEC_FLAG_CORE_BIT_EXACT;

libdcadec/dca_context.c

@@ -125,6 +125,9 @@ static void clip_samples(struct dcadec_context *dca, int nchannels)
 {
     int nsamples = dca->nframesamples;
 
+    if (dca->flags & DCADEC_FLAG_DONT_CLIP)
+        return;
+
     switch (dca->bits_per_sample) {
     case 24:
         for (int ch = 0; ch < nchannels; ch++)
@@ -721,8 +724,7 @@ static int filter_hd_ma_frame(struct dcadec_context *dca)
     dca->profile = DCADEC_PROFILE_HD_MA;
 
     // Perform clipping
-    if (dca->flags & DCADEC_FLAG_KEEP_DMIX_MASK)
-        clip_samples(dca, ret);
+    clip_samples(dca, ret);
 
     return 0;
 }

libdcadec/dca_context.h

@@ -113,6 +113,9 @@
 
 /** Don't conceal errors */
 #define DCADEC_FLAG_STRICT              0x100
+
+/** Don't clip returned PCM samples to output bit depth */
+#define DCADEC_FLAG_DONT_CLIP           0x200
 /**@}*/
 
 /**@{*/