[Bug] Psirius Memories of Time differs between OMPT and libxmp

[knight-ryu12]

This have playback issues between OMPT and Libxmp with weird artifact plays on Ord 1 on libxmp, where OpenMPT doesn't.

Modarchive

[sezero]

@AliceLR ?

[sezero]

Is Alice unwell?

[knight-ryu12]

I wonder as well...

[AliceLR]

Is the issue specifically in channels 21 and 22, i.e. does this command produce all of the affected notes?

xmp psirius_-_memories_of_time.xm -s 1 -M 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28,29,30,31

This is the only problem I've heard so far. The affected instrument has some very weird sample loop parameters that OpenMPT and libxmp truncate differently. i am dumb it's just stereo

[knight-ryu12]

Yeah it does; some high-pitched (wrong instrument?), and yes. probably issue with older OMPT (Since this module indicate itself as saved with OMPT)

[AliceLR]

Does it sound alright with this patch? This doesn't fix the fundamental issue (missing stereo sample support), just the junk sample data from delta decoding the right channel.

diff --git a/src/loaders/xm.h b/src/loaders/xm.h
index 6a863183..4d41486c 100644
--- a/src/loaders/xm.h
+++ b/src/loaders/xm.h
@@ -14,6 +14,7 @@
 #define XM_LOOP_FORWARD 1
 #define XM_LOOP_PINGPONG 2
 #define XM_SAMPLE_16BIT 0x10
+#define XM_SAMPLE_STEREO 0x20
 #define XM_ENVELOPE_ON 0x01
 #define XM_ENVELOPE_SUSTAIN 0x02
 #define XM_ENVELOPE_LOOP 0x04
diff --git a/src/loaders/xm_load.c b/src/loaders/xm_load.c
index 9919ad82..282cbe28 100644
--- a/src/loaders/xm_load.c
+++ b/src/loaders/xm_load.c
@@ -683,6 +683,12 @@ static int load_instruments(struct module_data *m, int version, HIO_HANDLE *f)
 				xxs->lps >>= 1;
 				xxs->lpe >>= 1;
 			}
+			if (xsh[j].type & XM_SAMPLE_STEREO) {
+				/* xxs->flg |= XMP_SAMPLE_STEREO; */
+				xxs->len >>= 1;
+				xxs->lps >>= 1;
+				xxs->lpe >>= 1;
+			}
 
 			xxs->flg |= xsh[j].type & XM_LOOP_FORWARD ? XMP_SAMPLE_LOOP : 0;
 			xxs->flg |= xsh[j].type & XM_LOOP_PINGPONG ? XMP_SAMPLE_LOOP | XMP_SAMPLE_LOOP_BIDIR : 0;
@@ -736,6 +742,11 @@ static int load_instruments(struct module_data *m, int version, HIO_HANDLE *f)
 				} else {
 					total_sample_size += xsh[j].length;
 				}
+
+				/* TODO: workaround for missing stereo sample support */
+				if (xsh[j].type & XM_SAMPLE_STEREO) {
+					hio_seek(f, xsh[j].length >> 1, SEEK_CUR);
+				}
 			}
 		}
 

[knight-ryu12]

Will check in few.

[knight-ryu12]

Just tested; It works fine.