Adjust tri-Ace codec issues

src/coding/tac_decoder.c

@@ -12,7 +12,7 @@ struct tac_codec_data {
     int encoder_delay;
 
     uint8_t buf[TAC_BLOCK_SIZE];
-    int read_block;
+    int feed_block;
     off_t offset;
 
     int16_t* samples;
@@ -38,7 +38,7 @@ tac_codec_data* init_tac(STREAMFILE* sf) {
     data->handle = tac_init(data->buf, bytes);
     if (!data->handle) goto fail;
 
-    data->read_block = 0; /* ok to use current block */
+    data->feed_block = 0; /* ok to use current block */
     data->offset = bytes;
     data->channels = TAC_CHANNELS;
     data->frame_samples = TAC_FRAME_SAMPLES;
@@ -66,15 +66,17 @@ static int decode_frame(tac_codec_data* data) {
     err = tac_decode_frame(data->handle, data->buf);
 
     if (err == TAC_PROCESS_NEXT_BLOCK) {
-        data->read_block = 1;
+        data->feed_block = 1;
         return 1;
     }
 
     if (err == TAC_PROCESS_DONE) {
+        VGM_LOG("TAC: process done (EOF) %i\n", err);
         goto fail; /* shouldn't reach this */
     }
     
     if (err != TAC_PROCESS_OK) {
+        VGM_LOG("TAC: process error %i\n", err);
         goto fail;
     }
 
@@ -90,10 +92,10 @@ fail:
 static int read_frame(tac_codec_data* data, STREAMFILE* sf) {
 
     /* new block must be read only when signaled by lib */
-    if (data->read_block) {
+    if (data->feed_block) {
         int bytes = read_streamfile(data->buf, data->offset, sizeof(data->buf), sf);
         data->offset += bytes;
-        data->read_block = 0;
+        data->feed_block = 0;
         if (bytes <= 0) goto fail; /* can read less that buf near EOF */
     }
 
@@ -139,7 +141,8 @@ void reset_tac(tac_codec_data* data) {
 
     tac_reset(data->handle);
 
-    data->read_block = 1;
+    data->offset = 0;
+    data->feed_block = 1;
     data->sbuf.filled = 0;
     data->samples_discard = data->encoder_delay;
 
@@ -149,20 +152,19 @@ void reset_tac(tac_codec_data* data) {
 void seek_tac(tac_codec_data* data, int32_t num_sample) {
     int32_t loop_sample;
     const tac_header_t* hdr;
-    
+
     if (!data)
         return;
 
     hdr = tac_get_header(data->handle);
 
-    loop_sample = hdr->loop_frame * TAC_FRAME_SAMPLES + hdr->loop_discard;
+    loop_sample = (hdr->loop_frame - 1) * TAC_FRAME_SAMPLES + hdr->loop_discard;
     if (loop_sample == num_sample) {
-        /* simulates original looping (that wouldn't clean codec internals) */
-        tac_set_loop(data->handle);
+        tac_set_loop(data->handle); /* direct looping */
 
         data->samples_discard = hdr->loop_discard;
         data->offset = hdr->loop_offset;
-        data->read_block = 1;
+        data->feed_block = 1;
         data->sbuf.filled = 0;
     }
     else {
@@ -170,7 +172,7 @@ void seek_tac(tac_codec_data* data, int32_t num_sample) {
 
         data->samples_discard = num_sample;
         data->offset = 0;
-        data->read_block = 1;
+        data->feed_block = 1;
         data->sbuf.filled = 0;
     }
 }

src/coding/tac_decoder_lib.c

@@ -16,8 +16,8 @@
  * container?) and handler lib may be "Csd". Looks inspired by MPEG (much simplified) with bits
  * from other codecs (per-file codebook and 1024 samples).
  *
- * Original decoder is implemented in the PS2's VU1, a coprocessor specialized in vector/SIMD and
- * parallel instructions. As VU1 works with many 128 bit registers (typically x4 floats) algorithm
+ * Original decoder is mainly implemented in the PS2's VU1, a coprocessor specialized in vector/SIMD
+ * and parallel instructions. As VU1 works with many 128 bit registers (typically x4 floats) algorithm
  * was tailored to do multiple ops at once. This code tries to simplify it into standard C to a point,
  * but keeps this vector style in main decoding to ease porting (since tables are made with SIMD in
  * mind it would need some transposing around) and for PS2 float simulation.
@@ -1053,7 +1053,7 @@ static int init_header(tac_header_t* header, const uint8_t* buf) {
     /* header size ia block-aligned (but actual size can be smaller, ex. VP 00000715) */
     if (header->file_size % TAC_BLOCK_SIZE != 0)
         return TAC_PROCESS_HEADER_ERROR;
-    /* assumed but should be ok */
+    /* loop_discard over max makes game crash, while frame_discard seems to ignore it */
     if (header->loop_discard > TAC_FRAME_SAMPLES || header->frame_discard > TAC_FRAME_SAMPLES)
         return TAC_PROCESS_HEADER_ERROR;
     /* looping makes sense */

src/coding/tac_decoder_lib.h

@@ -24,15 +24,15 @@ typedef struct tac_handle_t tac_handle_t;
 typedef struct {
     /* 0x20 header config */
     uint32_t huffman_offset;    /* setup */
-    uint32_t unknown;           /* ignored? may be CDVD stuff (divided/multiplied during PS2 process), not file size related */
-    uint16_t loop_frame;        /* aligned to block stard */
-    uint16_t loop_discard;      /* assumed */
-    uint16_t frame_count;       /* number of valid frames ("block end" frame not included) */
-    uint16_t frame_discard;     /* assumed */
-    uint32_t loop_offset;       /* file size if not looped */
-    uint32_t file_size;         /* actual file size can be a bit smaller if last block is truncated */
+    uint32_t unknown;           /* ignored? (may be CDVD stuff, divided/multiplied during PS2 process, not size related) */
+    uint16_t loop_frame;        /* aligned to block start */
+    uint16_t loop_discard;      /* discarded start samples in loop frame (lower = outputs more) */
+    uint16_t frame_count;       /* number of valid frames ("block end" frames not included) */
+    uint16_t frame_discard;     /* discarded end samples in final frame (lower = outputs less), even for non-looped files */
+    uint32_t loop_offset;       /* points to a block; file size if not looped */
+    uint32_t file_size;         /* block aligned; actual file size can be a bit smaller if last block is truncated */
     uint32_t joint_stereo;      /* usually 0 and rarely 1 */
-    uint32_t empty;             /* null? */
+    uint32_t empty;             /* always null */
 } tac_header_t;
 
 

src/meta/tac.c

@@ -35,7 +35,7 @@ VGMSTREAM* init_vgmstream_tac(STREAMFILE* sf) {
         goto fail;
 
     channel_count = 2; /* always stereo */
-    loop_flag = (loop_offset != stream_size);
+    loop_flag = (loop_offset != stream_size); /* actual check may be loop_frame > 0? */
     start_offset = 0;
 
 
@@ -45,8 +45,8 @@ VGMSTREAM* init_vgmstream_tac(STREAMFILE* sf) {
 
     vgmstream->meta_type = meta_TAC;
     vgmstream->sample_rate = 48000;
-    vgmstream->num_samples = frame_count * 1024 - frame_discard;
-    vgmstream->loop_start_sample = loop_frame * 1024 + loop_discard;
+    vgmstream->num_samples = frame_count * 1024 - (1024 - frame_discard);
+    vgmstream->loop_start_sample = (loop_frame - 1) * 1024 + loop_discard;
     vgmstream->loop_end_sample = vgmstream->num_samples;
 
     {