Add TXTH codec XA_EA [Road Rash videos (SAT)]

doc/TXTH.md

@@ -157,6 +157,8 @@ as explained below, but often will use default values. Accepted codec strings:
 #   * For rare EA games [Harry Potter and the Chamber of Secrets (PC)]
 # - XA             CD-XA ADPCM (ISO 2048 mode1/data streams without subchannels)
 #   * For rare Saturn and PS2 games [Phantasy Star Collection (SAT), Fantavision (PS2), EA SAT videos]
+# - XA_EA         Electronic Arts XA ADPCM variation
+#   * For rare Saturn games [EA SAT videos]
 # - CP_YM          Capcom's Yamaha ADPCM
 #   * For rare Saturn games [Marvel Super Heroes vs Street Fighter (SAT)]
 codec = (codec string)

src/coding/xa_decoder.c

@@ -5,14 +5,36 @@
 //#define XA_FLOAT 1
 #if XA_FLOAT
 /* floats as defined by the spec, but PS1's SPU would use int math */
-static const float K0[4] = { 0.0, 0.9375, 1.796875, 1.53125 };
+static const float K0[4+12] = { 0.0, 0.9375, 1.796875, 1.53125 };
-static const float K1[4] = { 0.0,    0.0,  -0.8125, -0.859375 };
+static const float K1[4+12] = { 0.0,    0.0,  -0.8125, -0.859375 };
 #else
-/* K0/1 floats to int with N=6: K*2^6 = K*(1<<6) = K*64 */
+/* K0/1 floats to int with N=6: K*2^6 = K*(1<<6) = K*64 (upper ranges are supposedly 0)*/
-static const int K0[4] = {  0,   60,  115,  98 };
+static const int K0[4+12] = {  0,   60,  115,  98 };
-static const int K1[4] = {  0,    0,  -52, -55 };
+static const int K1[4+12] = {  0,    0,  -52, -55 };
 #endif
 
+/* EA's extended XA (N=8), reverse engineered from SAT exes. Basically the same with minor
+ * diffs and extra steps probably for the SH2 CPU (only does 1/2/8 shifts) */
+static const int16_t EA_TABLE[16][2] = {
+    {   0,    0 },
+    { 240,    0 },
+    { 460, -208 },
+    { 392, -220 },
+    { 488, -240 },
+    { 328, -208 },
+    { 440, -168 },
+    { 420, -188 },
+    { 432, -176 },
+    { 240,  -16 },
+    { 416, -192 },
+    { 424, -160 },
+    { 288,   -8 },
+    { 436, -188 },
+    { 224,   -1 },
+    { 272,  -16 },
+};
+
+
 /* Sony XA ADPCM, defined for CD-DA/CD-i in the "Red Book" (private) or "Green Book" (public) specs.
  * The algorithm basically is BRR (Bit Rate Reduction) from the SNES SPC700, while the data layout is new.
  *
@@ -26,6 +48,7 @@ typedef struct {
     int32_t hist2;
     int subframes;
     int is_xa8;
+    int is_ea;
 } xa_t;
 
 static void decode_xa_frame(xa_t* xa, int32_t first_sample, int32_t samples_to_do, int channel) {
@@ -37,7 +60,7 @@ static void decode_xa_frame(xa_t* xa, int32_t first_sample, int32_t samples_to_d
     for (i = 0; i < xa->subframes / xa->channels; i++) {
         uint8_t sp;
         int index, shift, sp_pos;
-#if XA_FLOAT
+#ifdef XA_FLOAT
         float coef1, coef2;
 #else
         int32_t coef1, coef2;
@@ -52,14 +75,19 @@ static void decode_xa_frame(xa_t* xa, int32_t first_sample, int32_t samples_to_d
         shift = (sp >> 0) & 0xf;
 
         /* mastered values like 0xFF exist [Micro Machines (CDi), demo and release] */
-        VGM_ASSERT_ONCE(index > 4 || shift > shift_max, "XA: incorrect coefs/shift %x\n", sp);
+        VGM_ASSERT_ONCE(shift > shift_max, "XA: incorrect shift %x\n", sp);
-        if (index > 4)
-            index = 0; /* only 4 filters are used, rest is apparently 0 */
         if (shift > shift_max)
             shift = shift_limit;
 
+        if (xa->is_ea) {
+            coef1 = EA_TABLE[index][0];
+            coef2 = EA_TABLE[index][1];
+        }
+        else {
+            VGM_ASSERT_ONCE(index > 4, "XA: incorrect coefs %x\n", sp);
             coef1 = K0[index];
             coef2 = K1[index];
+        }
 
 
         /* decode subframe nibbles */
@@ -99,12 +127,19 @@ static void decode_xa_frame(xa_t* xa, int32_t first_sample, int32_t samples_to_d
 #if XA_FLOAT
             sample = sample + (coef1 * xa->hist1 + coef2 * xa->hist2);
 #else
+            if (xa->is_ea) /* sample << 8 actually but UB on negatives */
+                sample = (sample * 256 + coef1 * xa->hist1 + coef2 * xa->hist2) >> 8;
+            else
                 sample = sample + ((coef1 * xa->hist1 + coef2 * xa->hist2 + 32) >> 6);
 #endif
 
             xa->hist2 = xa->hist1;
             xa->hist1 = sample;
-            xa->sbuf[samples_done * xa->channels] = clamp16(sample); /* don't clamp hist */
+            sample = clamp16(sample); /* don't clamp hist */
+            if (xa->is_ea)
+                xa->hist1 = sample; /* do clamp hist */
+
+            xa->sbuf[samples_done * xa->channels] = sample;
             samples_done++;
 
             sample_count++;
@@ -123,8 +158,9 @@ void decode_xa(VGMSTREAM* v, sample_t* outbuf, int32_t samples_to_do) {
     int32_t first_sample = v->samples_into_block;
     xa_t xa;
 
-    xa.channels = v->channels;
+    xa.channels = v->channels > 1 ? 2 : 1; /* only stereo/mono modes */
     xa.is_xa8 = (v->coding_type == coding_XA8);
+    xa.is_ea = (v->coding_type == coding_XA_EA);
     xa.subframes = (xa.is_xa8) ? 4 : 8;
 
     /* external interleave (fixed size), mono/stereo */
@@ -139,7 +175,9 @@ void decode_xa(VGMSTREAM* v, sample_t* outbuf, int32_t samples_to_do) {
     if (bytes != sizeof(xa.frame)) /* ignore EOF errors */
         memset(xa.frame + bytes, 0, bytes_per_frame - bytes);
 
-    VGM_ASSERT_ONCE(get_u32be(xa.frame+0x0) != get_u32be(xa.frame+0x4) || get_u32be(xa.frame+0x8) != get_u32be(xa.frame+0xC),
+    /* headers should repeat in pairs, except in EA's modified XA */
+    VGM_ASSERT_ONCE(!xa.is_ea &&
+            (get_u32be(xa.frame+0x0) != get_u32be(xa.frame+0x4) || get_u32be(xa.frame+0x8) != get_u32be(xa.frame+0xC)),
             "bad frames at %x\n", frame_offset);
 
     for (ch = 0; ch < xa.channels; ch++) {
@@ -212,10 +250,11 @@ size_t xa_bytes_to_samples(size_t bytes, int channels, int is_blocked, int is_fo
  * Info (Green Book): https://www.lscdweb.com/data/downloadables/2/8/cdi_may94_r2.pdf
  * BRR info (no$sns): http://problemkaputt.de/fullsnes.htm#snesapudspbrrsamples
  *           (bsnes): https://github.com/byuu/bsnes/blob/master/bsnes/sfc/dsp/SPC_DSP.cpp#L316
+ * Note that this is just called "ADPCM" in the "CD-ROM XA" spec (rather than "XA ADPCM" being the actual name).
  */ 
 
 /* data layout (mono):
- * - CD-XA audio is divided into sectors ("audio blocks"), each with 18*0x80 frames
+ * - CD XA audio is divided into sectors ("audio blocks"), each with 18*0x80 frames
  *   (sectors are handled externally, this decoder only sees 0x80 frames)
  * - each frame ("sound group") is divided into 8 interleaved subframes ("sound unit"), with
  *   8*0x01 subframe headers x2 ("sound parameters") first then 28*0x04 subframe nibbles ("sound data")

src/decode.c

@@ -442,6 +442,7 @@ int get_vgmstream_samples_per_frame(VGMSTREAM* vgmstream) {
             return 0; /* variable (block-controlled) */
 
         case coding_XA:
+        case coding_XA_EA:
             return 28*8 / vgmstream->channels; /* 8 subframes per frame, mono/stereo */
         case coding_XA8:
             return 28*4 / vgmstream->channels; /* 4 subframes per frame, mono/stereo */
@@ -660,6 +661,7 @@ int get_vgmstream_frame_size(VGMSTREAM* vgmstream) {
             return 0x00; /* variable (block-controlled) */
 
         case coding_XA:
+        case coding_XA_EA:
         case coding_XA8:
             return 0x80;
         case coding_PSX:
@@ -1007,6 +1009,7 @@ void decode_vgmstream(VGMSTREAM* vgmstream, int samples_written, int samples_to_
             }
             break;
         case coding_XA:
+        case coding_XA_EA:
         case coding_XA8: {
             decode_xa(vgmstream, buffer, samples_to_do);
             break;

src/meta/txth.c

@@ -41,6 +41,7 @@ typedef enum {
     EAXA = 31,          /* Electronic Arts EA-XA 4-bit ADPCM v1 */
     OKI4S = 32,         /* OKI ADPCM with 16-bit output (unlike OKI/VOX/Dialogic ADPCM's 12-bit) */
     XA,
+    XA_EA,
     CP_YM,
 
     UNKNOWN = 99,
@@ -262,6 +263,7 @@ VGMSTREAM* init_vgmstream_txth(STREAMFILE* sf) {
         case ASF:        coding = coding_ASF; break;
         case EAXA:       coding = coding_EA_XA; break;
         case XA:         coding = coding_XA; break;
+        case XA_EA:      coding = coding_XA_EA; break;
         case CP_YM:      coding = coding_CP_YM; break;
         default:
             goto fail;
@@ -375,6 +377,7 @@ VGMSTREAM* init_vgmstream_txth(STREAMFILE* sf) {
         case coding_OKI16:
         case coding_OKI4S:
         case coding_XA:
+        case coding_XA_EA:
         case coding_CP_YM:
             vgmstream->layout_type = layout_none;
             break;
@@ -948,6 +951,7 @@ static txth_codec_t parse_codec(txth_header* txth, const char* val) {
     else if (is_string(val,"ASF"))          return ASF;
     else if (is_string(val,"EAXA"))         return EAXA;
     else if (is_string(val,"XA"))           return XA;
+    else if (is_string(val,"XA_EA"))        return XA_EA;
     else if (is_string(val,"CP_YM"))        return CP_YM;
     /* special handling */
     else if (is_string(val,"name_value"))   return txth->name_values[0];
@@ -2031,6 +2035,7 @@ static int get_bytes_to_samples(txth_header* txth, uint32_t bytes) {
         case EAXA:
             return ea_xa_bytes_to_samples(bytes, txth->channels);
         case XA:
+        case XA_EA:
             return xa_bytes_to_samples(bytes, txth->channels, 0, 0, 4);
 
         /* XMA bytes-to-samples is done at the end as the value meanings are a bit different */

src/vgmstream.h

@@ -87,6 +87,7 @@ typedef enum {
 
     coding_XA,              /* CD-ROM XA 4-bit */
     coding_XA8,             /* CD-ROM XA 8-bit */
+    coding_XA_EA,           /* EA's Saturn XA (not to be confused with EA-XA) */
     coding_PSX,             /* Sony PS ADPCM (VAG) */
     coding_PSX_badflags,    /* Sony PS ADPCM with custom flag byte */
     coding_PSX_cfg,         /* Sony PS ADPCM with configurable frame size (int math) */