Added 4-bit PCM decoder

src/coding/coding.h

@@ -71,6 +71,8 @@ void decode_pcm8_int(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspac
 void decode_pcm8_unsigned(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);
 void decode_pcm8_unsigned_int(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);
 void decode_pcm8_sb(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);
+void decode_pcm4(VGMSTREAM * vgmstream, VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel);
+void decode_pcm4_unsigned(VGMSTREAM * vgmstream, VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel);
 void decode_ulaw(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);
 void decode_ulaw_int(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);
 void decode_alaw(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do);

src/coding/pcm_decoder.c

@@ -78,6 +78,52 @@ void decode_pcm8_sb(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspaci
     }
 }
 
+void decode_pcm4(VGMSTREAM * vgmstream, VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel) {
+    int i, nibble_shift, is_high_first, is_stereo;
+    int32_t sample_count;
+    uint16_t sample;
+    off_t byte_offset;
+
+    is_high_first = (vgmstream->codec_config & 1);
+    is_stereo = (vgmstream->channels != 1);
+
+    for (i=first_sample,sample_count=0; i<first_sample+samples_to_do; i++,sample_count+=channelspacing) {
+        byte_offset = is_stereo ?
+                stream->offset + i :    /* stereo: one nibble per channel (assumed, not sure if stereo version actually exists) */
+                stream->offset + i/2;   /* mono: consecutive nibbles */
+        nibble_shift = is_high_first ?
+                is_stereo ? (!(channel&1) ? 4:0) : (!(i&1) ? 4:0) : /* even = high, odd = low */
+                is_stereo ? (!(channel&1) ? 0:4) : (!(i&1) ? 0:4);  /* even = low, odd = high */
+
+        sample = (uint16_t)read_8bit(byte_offset, stream->streamfile);
+        sample = (sample >> nibble_shift) & 0x0F;
+        outbuf[sample_count] = sample*0x11*0x100;
+    }
+}
+
+void decode_pcm4_unsigned(VGMSTREAM * vgmstream, VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do, int channel) {
+    int i, nibble_shift, is_high_first, is_stereo;
+    int32_t sample_count;
+    uint16_t sample;
+    off_t byte_offset;
+
+    is_high_first = (vgmstream->codec_config & 1);
+    is_stereo = (vgmstream->channels != 1);
+
+    for (i=first_sample,sample_count=0; i<first_sample+samples_to_do; i++,sample_count+=channelspacing) {
+        byte_offset = is_stereo ?
+                stream->offset + i :    /* stereo: one nibble per channel (assumed, not sure if stereo version actually exists) */
+                stream->offset + i/2;   /* mono: consecutive nibbles */
+        nibble_shift = is_high_first ?
+                is_stereo ? (!(channel&1) ? 4:0) : (!(i&1) ? 4:0) : /* even = high, odd = low */
+                is_stereo ? (!(channel&1) ? 0:4) : (!(i&1) ? 0:4);  /* even = low, odd = high */
+
+        sample = (uint16_t)read_8bit(byte_offset, stream->streamfile);
+        sample = (sample >> nibble_shift) & 0x0F;
+        outbuf[sample_count] = sample*0x11*0x100 - 0x8000;
+    }
+}
+
 static int expand_ulaw(uint8_t ulawbyte) {
     int sign, segment, quantization, new_sample;
     const int bias = 0x84;
@@ -175,5 +221,5 @@ void decode_pcmfloat(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspac
 }
 
 size_t pcm_bytes_to_samples(size_t bytes, int channels, int bits_per_sample) {
-    return bytes / channels / (bits_per_sample/8);
+    return (bytes * 8) / channels / bits_per_sample;
 }

src/formats.c

@@ -551,11 +551,13 @@ static const coding_info coding_info_list[] = {
         {coding_PCM16LE,            "Little Endian 16-bit PCM"},
         {coding_PCM16BE,            "Big Endian 16-bit PCM"},
         {coding_PCM16_int,          "16-bit PCM with 2 byte interleave (block)"},
-        {coding_PCM8,               "8-bit PCM"},
+        {coding_PCM8,               "8-bit signed PCM"},
-        {coding_PCM8_int,           "8-bit PCM with 1 byte interleave (block)"},
+        {coding_PCM8_int,           "8-bit signed PCM with 1 byte interleave (block)"},
         {coding_PCM8_U,             "8-bit unsigned PCM"},
         {coding_PCM8_U_int,         "8-bit unsigned PCM with 1 byte interleave (block)"},
         {coding_PCM8_SB,            "8-bit PCM with sign bit"},
+        {coding_PCM4,               "4-bit signed PCM"},
+        {coding_PCM4_U,             "4-bit unsigned PCM"},
         {coding_ULAW,               "8-bit u-Law"},
         {coding_ULAW_int,           "8-bit u-Law with 1 byte interleave (block)"},
         {coding_ALAW,               "8-bit a-Law"},

src/meta/genh.c

@@ -31,6 +31,8 @@ typedef enum {
     FFMPEG = 22,      /* any headered FFmpeg format */
     AC3 = 23,         /* AC3/SPDIF */
     PCFX = 24,        /* PC-FX ADPCM */
+    PCM4 = 25,        /* 4bit signed PCM */
+    PCM4_U = 26,      /* 4bit unsigned PCM */
 } genh_type;
 
 typedef struct {
@@ -114,6 +116,8 @@ VGMSTREAM * init_vgmstream_genh(STREAMFILE *streamFile) {
         case FFMPEG:     coding = coding_FFmpeg; break;
 #endif
         case PCFX:       coding = coding_PCFX; break;
+        case PCM4:       coding = coding_PCM4; break;
+        case PCM4_U:     coding = coding_PCM4_U; break;
         default:
             goto fail;
     }
@@ -137,6 +141,8 @@ VGMSTREAM * init_vgmstream_genh(STREAMFILE *streamFile) {
         case coding_PCM16BE:
         case coding_PCM8:
         case coding_PCM8_U:
+        case coding_PCM4:
+        case coding_PCM4_U:
         case coding_SDX2:
         case coding_PSX:
         case coding_PSX_badflags:
@@ -185,6 +191,10 @@ VGMSTREAM * init_vgmstream_genh(STREAMFILE *streamFile) {
                 }
             }
 
+            if (coding == coding_PCM4 || coding == coding_PCM4_U) {
+                /* high nibble or low nibble first */
+                vgmstream->codec_config = genh.codec_mode;
+            }
             break;
 
         case coding_PCFX:

src/meta/txth.c

@@ -31,6 +31,8 @@ typedef enum {
     FFMPEG = 22,      /* any headered FFmpeg format */
     AC3 = 23,         /* AC3/SPDIF */
     PCFX = 24,        /* PC-FX ADPCM */
+    PCM4 = 25,        /* 4bit signed PCM */
+    PCM4_U = 26,      /* 4bit unsigned PCM */
 } txth_type;
 
 typedef struct {
@@ -176,6 +178,8 @@ VGMSTREAM * init_vgmstream_txth(STREAMFILE *streamFile) {
         case FFMPEG:     coding = coding_FFmpeg; break;
 #endif
         case PCFX:       coding = coding_PCFX; break;
+        case PCM4:       coding = coding_PCM4; break;
+        case PCM4_U:     coding = coding_PCM4_U; break;
         default:
             goto fail;
     }
@@ -212,6 +216,8 @@ VGMSTREAM * init_vgmstream_txth(STREAMFILE *streamFile) {
         case coding_PCM16BE:
         case coding_PCM8:
         case coding_PCM8_U:
+        case coding_PCM4:
+        case coding_PCM4_U:
         case coding_SDX2:
         case coding_PSX:
         case coding_PSX_badflags:
@@ -260,6 +266,11 @@ VGMSTREAM * init_vgmstream_txth(STREAMFILE *streamFile) {
                     vgmstream->ch[i].adpcm_step_index = 0x7f;
                 }
             }
+
+            if (coding == coding_PCM4 || coding == coding_PCM4_U) {
+                /* high nibble or low nibble first */
+                vgmstream->codec_config = txth.codec_mode;
+            }
             break;
 
         case coding_PCFX:
@@ -583,6 +594,8 @@ static int parse_keyval(STREAMFILE * streamFile_, txth_header * txth, const char
         else if (0==strcmp(val,"FFMPEG"))       txth->codec = FFMPEG;
         else if (0==strcmp(val,"AC3"))          txth->codec = AC3;
         else if (0==strcmp(val,"PCFX"))         txth->codec = PCFX;
+        else if (0==strcmp(val,"PCM4"))         txth->codec = PCM4;
+        else if (0==strcmp(val,"PCM4_U"))       txth->codec = PCM4_U;
         else goto fail;
     }
     else if (0==strcmp(key,"codec_mode")) {
@@ -913,6 +926,9 @@ static int get_bytes_to_samples(txth_header * txth, uint32_t bytes) {
         case PCM8_U_int:
         case PCM8_U:
             return pcm_bytes_to_samples(bytes, txth->channels, 8);
+        case PCM4:
+        case PCM4_U:
+            return pcm_bytes_to_samples(bytes, txth->channels, 4);
         case MSADPCM:
             if (!txth->interleave) return 0;
             return msadpcm_bytes_to_samples(bytes, txth->interleave, txth->channels);

src/vgmstream.c

@@ -1550,6 +1550,18 @@ void decode_vgmstream(VGMSTREAM * vgmstream, int samples_written, int samples_to
                         vgmstream->channels,vgmstream->samples_into_block,samples_to_do);
             }
             break;
+        case coding_PCM4:
+            for (ch = 0; ch < vgmstream->channels; ch++) {
+                decode_pcm4(vgmstream,&vgmstream->ch[ch],buffer+samples_written*vgmstream->channels+ch,
+                        vgmstream->channels,vgmstream->samples_into_block,samples_to_do,ch);
+            }
+            break;
+        case coding_PCM4_U:
+            for (ch = 0; ch < vgmstream->channels; ch++) {
+                decode_pcm4_unsigned(vgmstream, &vgmstream->ch[ch],buffer+samples_written*vgmstream->channels+ch,
+                        vgmstream->channels,vgmstream->samples_into_block,samples_to_do,ch);
+            }
+            break;
 
         case coding_ULAW:
             for (ch = 0; ch < vgmstream->channels; ch++) {

src/vgmstream.h

@@ -73,6 +73,8 @@ typedef enum {
     coding_PCM8_U,          /* 8-bit PCM, unsigned (0x80 = 0) */
     coding_PCM8_U_int,      /* 8-bit PCM, unsigned (0x80 = 0) with sample-level interleave (for blocks) */
     coding_PCM8_SB,         /* 8-bit PCM, sign bit (others are 2's complement) */
+    coding_PCM4,            /* 4-bit PCM, signed */
+    coding_PCM4_U,          /* 4-bit PCM, unsigned */
 
     coding_ULAW,            /* 8-bit u-Law (non-linear PCM) */
     coding_ULAW_int,        /* 8-bit u-Law (non-linear PCM) with sample-level interleave (for blocks) */