Fix some MUSX .sfx [Sphinx (PC)]

src/coding/coding.h

@@ -48,7 +48,7 @@ size_t ms_ima_bytes_to_samples(size_t bytes, int block_align, int channels);
 size_t xbox_ima_bytes_to_samples(size_t bytes, int channels);
 size_t dat4_ima_bytes_to_samples(size_t bytes, int channels);
 size_t apple_ima4_bytes_to_samples(size_t bytes, int channels);
-
+int xbox_check_format(STREAMFILE* sf, uint32_t offset, uint32_t max, int channels);
 
 /* ngc_dsp_decoder */
 void decode_ngc_dsp(VGMSTREAMCHANNEL* stream, sample_t* outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);

src/coding/ima_decoder.c

@@ -1326,3 +1326,27 @@ size_t apple_ima4_bytes_to_samples(size_t bytes, int channels) {
     return (bytes / block_align) * (block_align - 0x02*channels) * 2 / channels
             + ((bytes % block_align) ? ((bytes % block_align) - 0x02*channels) * 2 / channels : 0);
 }
+
+
+/* test XBOX-ADPCM frames for correctness */
+int xbox_check_format(STREAMFILE* sf, uint32_t offset, uint32_t max, int channels) {
+    off_t max_offset = offset + max;
+    int ch;
+
+    if (max_offset > get_streamfile_size(sf))
+        max_offset = get_streamfile_size(sf);
+    if (!channels)
+        return 0;
+
+    while (offset < max_offset) {
+        for (ch = 0; ch < channels; ch++) {
+            uint16_t step = read_u16le(offset + 0x04 * ch + 0x02,sf);
+            if (step > 88)
+                return 0;
+        }
+
+        offset += 0x24 * channels;
+    }
+
+    return 1;
+}

src/meta/musx.c

@@ -1,5 +1,6 @@
 #include "meta.h"
 #include "../coding/coding.h"
+#include "../util/endianness.h"
 
 typedef enum { MFX, MFX_BANK, SFX_BANK, SBNK, FORM } musx_form;
 typedef enum { PSX, DSP, XBOX, IMA, DAT, NGCA, PCM } musx_codec;
@@ -187,16 +188,24 @@ static int parse_musx_stream(STREAMFILE* sf, musx_header* musx) {
             musx->platform = get_id32be("GC02"); /* (fake) */
         }
         else {
+            int channels = musx->channels;
             off_t offset = musx->stream_offset;
             size_t max = 0x5000;
             if (max > musx->stream_size)
                 max = musx->stream_size;
+            if (!channels)
+                channels = 2;
 
+            /* since engine seems to hardcode codecs no apparent way to detect in some cases
+             * [Sphinx and the Cursed Mummy (multi), Buffy the Vampire Slayer: Chaos Bleeds (multi)] */
             if (ps_check_format(sf, offset, max)) {
                 musx->platform = get_id32be("PS2_");
-            } else {
+            } else if (xbox_check_format(sf, offset, max, channels)) {
                 musx->platform = get_id32be("XB02"); /* (fake) */
             }
+            else {
+                musx->platform = get_id32be("PC02"); /* (fake) */
+            }
         }
     }
 
@@ -267,6 +276,12 @@ static int parse_musx_stream(STREAMFILE* sf, musx_header* musx) {
             musx->codec = DAT;
             break;
 
+        case 0x50433032: /* "PC02" */
+            default_channels = 2;
+            default_sample_rate = 32000;
+            musx->codec = IMA;
+            break;
+
         default:
             VGM_LOG("MUSX: unknown platform %x\n", musx->platform);
             goto fail;
@@ -307,7 +322,7 @@ static int parse_musx_stream(STREAMFILE* sf, musx_header* musx) {
             }
 
             /* other types (0x0a, 0x09) look like section/end markers, 0x06/07 only seems to exist once */
-            if (type == 0x06 || type == 0x07) {
+            if (type == 0x06 || type == 0x07) { /* loop / goto */
                 musx->loop_start = offset2;
                 musx->loop_end = offset1;
                 musx->loop_flag = 1;
@@ -361,6 +376,8 @@ fail:
     return 0;
 }
 
+//TODO: check possible info here:
+// https://sphinxandthecursedmummy.fandom.com/wiki/SFX
 static int parse_musx(STREAMFILE* sf, musx_header* musx) {
     int32_t (*read_s32)(off_t,STREAMFILE*) = NULL;
     uint32_t (*read_u32)(off_t,STREAMFILE*) = NULL;
@@ -378,7 +395,7 @@ static int parse_musx(STREAMFILE* sf, musx_header* musx) {
         case 1:     /* Athens 2004 (PS2) */
             musx->platform = 0; /* guess later */
             musx->tables_offset = 0x10;
-            musx->big_endian = guess_endianness32bit(0x10, sf);
+            musx->big_endian = guess_endian32(0x10, sf);
             musx->is_old = 1;
             break;
 
@@ -670,7 +687,7 @@ static int parse_musx(STREAMFILE* sf, musx_header* musx) {
                 data_offset = read_u32(musx->tables_offset+0x3c, sf);
 
                 target_offset = head_offset + (target_subsong - 1) * 0x1c;
-                ;VGM_LOG("MUSX: ho=%lx, do=%lx, to=%lx\n", head_offset, data_offset, target_offset);
+                //;VGM_LOG("MUSX: ho=%lx, do=%lx, to=%lx\n", head_offset, data_offset, target_offset);
 
                 /* 0x00: subfile ID */
                 musx->num_samples       = read_s32(target_offset + 0x04, sf);