Improve seeking speed

src/decode.c

@@ -1452,7 +1452,7 @@ int vgmstream_do_loop(VGMSTREAM* vgmstream) {
         vgmstream->loop_next_block_offset = vgmstream->next_block_offset;
         //vgmstream->lstate = vgmstream->pstate; /* play state is applied over loops */
 
-        vgmstream->hit_loop = 1;
+        vgmstream->hit_loop = 1; /* info that loop is now ready to use */
     }
 
     return 0; /* not looped */

src/render.c

@@ -1,6 +1,7 @@
 #include "vgmstream.h"
-#include "render.h"
 #include "layout/layout.h"
+#include "render.h"
+#include "decode.h"
 #include "mixing.h"
 #include "plugins.h"
 
@@ -194,7 +195,7 @@ static void setup_state_processing(VGMSTREAM* vgmstream) {
     ps->trim_begin_left = ps->trim_begin_duration;
     ps->fade_left = ps->fade_duration;
     ps->fade_start = ps->pad_begin_duration + ps->body_duration;
-    ps->pad_end_left = ps->pad_end_duration;
+  //ps->pad_end_left = ps->pad_end_duration;
     ps->pad_end_start = ps->fade_start + ps->fade_duration;
 
     /* other info (updated once mixing is enabled) */
@@ -431,7 +432,7 @@ int render_vgmstream(sample_t* buf, int32_t sample_count, VGMSTREAM* vgmstream)
     }
 
     /* end padding (done before to avoid decoding if possible) */
-    if (!vgmstream->config.play_forever /*&& ps->pad_end_left*/
+    if (!vgmstream->config.play_forever /* && ps->pad_end_left */
             && ps->play_position + samples_done >= ps->pad_end_start) {
         done = render_pad_end(vgmstream, tmpbuf, samples_to_do);
         samples_done += done;
@@ -474,54 +475,209 @@ int render_vgmstream(sample_t* buf, int32_t sample_count, VGMSTREAM* vgmstream)
     return samples_done;
 }
 
+/*****************************************************************************/
+
+static void seek_force_loop(VGMSTREAM* vgmstream) {
+    /* only called after hit loop */
+    if (!vgmstream->hit_loop)
+        return;
+
+    /* pretend decoder reached loop end so state is set to loop start */
+    vgmstream->loop_count = 0;
+    vgmstream->current_sample = vgmstream->loop_end_sample;
+    vgmstream_do_loop(vgmstream);
+}
+
+static void seek_force_decode(VGMSTREAM* vgmstream, int samples) {
+    sample_t tmpbuf[0x40000]; /* big-ish buffer as less calls = better */
+    int32_t buf_samples = 0x40000 / vgmstream->channels; /* base channels, no need to apply mixing */
+
+    int i;
+
+    for (i = 0; i < samples; i += buf_samples) {
+        int to_get = buf_samples;
+        if (i + buf_samples > samples)
+            to_get = samples - i;
+
+        render_layout(tmpbuf, to_get, vgmstream);
+        /* no mixing */
+    }
+}
 
 void seek_vgmstream(VGMSTREAM* vgmstream, int32_t seek_sample) {
     play_state_t* ps = &vgmstream->pstate;
-    sample_t tmpbuf[0x40000]; /* big-ish buffer as less calls = better */
+    int play_forever = vgmstream->config.play_forever;
-    int buf_samples = 0x40000 / vgmstream->channels; /* no need to apply mixing */
+
-    int i;
+    int32_t decode_samples = 0;
-  //int play_duration = ps->play_duration;
+    int loop_count = -1;
-    int play_pos = ps->play_position;
+    int is_looped = vgmstream->loop_flag || vgmstream->loop_target > 0; /* loop target disabled loop flag during decode */
-    int decode_samples = 0;
+
-  //int decode_pos = 0;
 
     if (!vgmstream->config_enabled) {
+        //todo same but ignore play duration or play_position
         return;
     }
 
-    //todo allow seeking past max for loop forever
+    //todo optimize layout looping with seek_vgmstream
-    /* seeking past max for loop forever */
+    //todo could improve performance bit if hit_loop wasn't lost when calling reset
-    //if (seek_sample > play_duration)
+    //todo wrong seek with ignore fade
-    //    seek_sample = play_duration;
 
-    /* find which relative decode sample corresponds to seek sample
-     * (if it falls in a pad or loop it can be simplified rather than decoding the full thing) */
-    //todo calculate
 
-    if (seek_sample < play_pos) {
+    /* seeking to requested sample normally means decoding and discarding up to that point (from
+     * the beginning, or current position), but can be optimized a bit to decode less with some tricks:
+     * - seek may fall in part of the song that isn't actually decoding (due to config, like padding)
+     * - if file loops there is no need to decode N full loops, seek can be set relative to loop region
+     * - can decode to seek sample from current position or loop start depending on lowest
+     *
+     * some of the cases below could be simplified but the logic to get this going is kinda mind-bending
+     *
+     *  (ex. with file = 100, pad=5s, trim=3s, loop=20s..90s)
+     *  |  pad-begin  |  body-begin | body-loop0 | body-loop1 | body-loop2 | fade |  pad-end + beyond)
+     *  0             5s   (-3s)    25s          95s          165s         235s   245s       Ns
+     */
+
+    if (seek_sample < 0)
+        seek_sample = 0;
+    if (seek_sample > ps->play_duration && !play_forever) /* play forever can seek to any loop */
+        seek_sample = ps->play_duration;
+
+    //;VGM_LOG("SEEK: seek sample=%i, is_looped=%i\n", seek_sample, is_looped);
+
+    /* start/pad-begin: consume pad samples */
+    if (seek_sample < ps->pad_begin_duration) {
+        /* seek=3: pad=5-3=2 */
+        decode_samples = 0;
+
         reset_vgmstream(vgmstream);
-        decode_samples = seek_sample;
+        ps->pad_begin_left = ps->pad_begin_duration - seek_sample;
+
+        //;VGM_LOG("SEEK: pad start / dec=%i\n", decode_samples);
     }
-    else if (seek_sample > play_pos) {
+
-        decode_samples = (seek_sample - play_pos);
+    /* body: find position relative to decoder's current sample */
+    else if (play_forever || seek_sample < ps->pad_begin_duration + ps->body_duration + ps->fade_duration) {
+        /* seek=10 would be seekr=10-5+3=8 inside decoder */
+        int32_t seek_relative = seek_sample - ps->pad_begin_duration + ps->trim_begin_duration;
+
+
+        //;VGM_LOG("SEEK: body / seekr=%i, curr=%i\n", seek_relative, vgmstream->current_sample);
+
+        /* seek can be in some part of the body, depending on looped/decoder's current/etc */
+        if (!is_looped && seek_relative < vgmstream->current_sample) {
+            /* seekr=50s, curr=95 > restart + decode=50s */
+            decode_samples = seek_relative;
+            reset_vgmstream(vgmstream);
+
+            //;VGM_LOG("SEEK: non-loop reset / dec=%i\n", decode_samples);
+        }
+        else if (!is_looped && seek_relative < vgmstream->num_samples) {
+            /* seekr=95s, curr=50 > decode=95-50=45s */
+            decode_samples = seek_relative - vgmstream->current_sample;
+
+            //;VGM_LOG("SEEK: non-loop forward / dec=%i\n", decode_samples);
+        }
+        else if (!is_looped) {
+            /* seekr=120s (outside decode, can happen when body is set manually) */
+            decode_samples = 0;
+            vgmstream->current_sample = vgmstream->num_samples + 1;
+
+            //;VGM_LOG("SEEK: non-loop silence / dec=%i\n", decode_samples);
+        }
+        else if (seek_relative < vgmstream->loop_start_sample) {
+            /* seekr=6s > 6-5+3 > seek=4s inside decoder < 20s: decode 4s from start, or 1s if current was at 3s */
+
+            if (seek_relative < vgmstream->current_sample) {
+                /* seekr=9s, current=10s > decode=9s from start */
+                decode_samples = seek_relative;
+                reset_vgmstream(vgmstream);
+
+                //;VGM_LOG("SEEK: loop start reset / dec=%i\n", decode_samples);
+            }
+            else {
+                /* seekr=9s, current=8s > decode=1s from current */
+                decode_samples = seek_relative - vgmstream->current_sample;
+
+                //;VGM_LOG("SEEK: loop start forward / dec=%i\n", decode_samples);
+            }
+        }
+        else {
+            /* seek can be clamped between loop parts (relative to decoder's current_sample) to minimize decoding */
+            int32_t loop_body, loop_seek, loop_curr;
+
+            /* current must have reached loop start at some point */
+            if (!vgmstream->hit_loop) {
+                int32_t skip_samples;
+
+                if (vgmstream->current_sample >= vgmstream->loop_start_sample) {
+                    VGM_LOG("SEEK: bad current sample %i vs %i\n", vgmstream->current_sample, vgmstream->loop_start_sample);
+                    reset_vgmstream(vgmstream);
+                }
+
+                skip_samples = (vgmstream->loop_start_sample - vgmstream->current_sample);
+                //;VGM_LOG("SEEK: must loop / skip=%i, curr=%i\n", skip_samples, vgmstream->current_sample);
+
+                seek_force_decode(vgmstream, skip_samples);
+            }
+
+            /* current must be in loop area (shouldn't happen?) */
+            if (vgmstream->current_sample < vgmstream->loop_start_sample
+                    || vgmstream->current_sample < vgmstream->loop_end_sample) {
+                //;VGM_LOG("SEEK: current outside loop area / curr=%i, ls=%i, le=%i\n", vgmstream->current_sample, vgmstream->current_sample, vgmstream->loop_end_sample);
+                seek_force_loop(vgmstream);
+            }
+
+
+            loop_body = (vgmstream->loop_end_sample - vgmstream->loop_start_sample);
+            loop_seek = seek_relative - vgmstream->loop_start_sample;
+            loop_count = loop_seek / loop_body;
+            loop_seek = loop_seek % loop_body;
+            loop_curr = vgmstream->current_sample - vgmstream->loop_start_sample;
+
+            //;VGM_LOG("SEEK: in loop / seekl=%i, loops=%i, cur=%i, dec=%i\n", loop_seek, loop_count, loop_curr, decode_samples);
+            if (loop_seek < loop_curr) {
+                decode_samples += loop_seek;
+                seek_force_loop(vgmstream);
+
+                //;VGM_LOG("SEEK: loop reset / dec=%i, loop=%i\n", decode_samples, loop_count);
+            }
+            else {
+                decode_samples += (loop_seek - loop_curr);
+
+                //;VGM_LOG("SEEK: loop forward / dec=%i, loop=%i\n", decode_samples, loop_count);
+            }
+
+            /* adjust fade if seek ends in fade region */
+            if (!play_forever
+                    && seek_sample >= ps->pad_begin_duration + ps->body_duration
+                    && seek_sample < ps->pad_begin_duration + ps->body_duration + ps->fade_duration) {
+                ps->fade_left = ps->pad_begin_duration + ps->body_duration + ps->fade_duration - seek_sample;
+                //;VGM_LOG("SEEK: in fade / fade=%i, %i\n", ps->fade_left, ps->fade_duration);
+            }
+        }
+
+        /* done at the end in case of reset */
+        ps->pad_begin_left = 0;
+        ps->trim_begin_left = 0;
     }
+
+    /* pad end and beyond: ignored */
     else {
-        return;
+        decode_samples = 0;
+        ps->pad_begin_left = 0;
+        ps->trim_begin_left = 0;
+        if (!is_looped)
+            vgmstream->current_sample = vgmstream->num_samples + 1;
+
+        //;VGM_LOG("SEEK: end silence / dec=%i\n", decode_samples);
+        /* looping decoder state isn't changed (seek backwards could use current sample) */
     }
 
 
-    for (i = 0; i < decode_samples; i += buf_samples) {
+    seek_force_decode(vgmstream, decode_samples);
-        int to_get = buf_samples;
-        if (i + buf_samples > decode_samples)
-            to_get = decode_samples - i;
-
-        render_vgmstream(tmpbuf, to_get, vgmstream);
-
-        //todo
-        //render_layout(tmpbuf, to_get, vgmstream);
-        ///* no mixing needed */
-    }
 
     /* adjust positions */
-    //todo
+    if (vgmstream->loop_count >= 0)
+        vgmstream->loop_count = loop_count;
+
+    vgmstream->pstate.play_position = seek_sample;
 }

src/vgmstream.c

@@ -529,7 +529,7 @@ VGMSTREAM* (*init_vgmstream_functions[])(STREAMFILE* sf) = {
 /* internal version with all parameters */
 static VGMSTREAM* init_vgmstream_internal(STREAMFILE* sf) {
     int i, fcns_size;
-    
+
     if (!sf)
         return NULL;
 
@@ -708,7 +708,7 @@ VGMSTREAM* allocate_vgmstream(int channel_count, int loop_flag) {
     /* create vgmstream + main structs (other data is 0'ed) */
     vgmstream = calloc(1,sizeof(VGMSTREAM));
     if (!vgmstream) return NULL;
-    
+
     vgmstream->start_vgmstream = calloc(1,sizeof(VGMSTREAM));
     if (!vgmstream->start_vgmstream) goto fail;
 
@@ -830,6 +830,8 @@ void vgmstream_force_loop(VGMSTREAM* vgmstream, int loop_flag, int loop_start_sa
 
 void vgmstream_set_loop_target(VGMSTREAM* vgmstream, int loop_target) {
     if (!vgmstream) return;
+    if (!vgmstream->loop_flag) return;
+
 
     vgmstream->loop_target = loop_target; /* loop count must be rounded (int) as otherwise target is meaningless */
 

src/vgmstream.h

@@ -834,7 +834,7 @@ typedef struct {
     int32_t fade_left;
     int32_t fade_start;
     int32_t pad_end_duration;
-    int32_t pad_end_left;
+  //int32_t pad_end_left;
     int32_t pad_end_start;
 
     int32_t play_duration;      /* total samples that the stream lasts (after applying all config) */
@@ -1111,7 +1111,7 @@ int32_t get_vgmstream_play_samples(double looptimes, double fadeseconds, double
 /* Decode data into sample buffer. Returns < sample_count on stream end */
 int render_vgmstream(sample_t* buffer, int32_t sample_count, VGMSTREAM* vgmstream);
 
-/* Seek to sample position (next render starts from that point). Use only with internal config set */
+/* Seek to sample position (next render starts from that point). Use only after config is set (vgmstream_apply_config) */
 void seek_vgmstream(VGMSTREAM* vgmstream, int32_t seek_sample);
 
 /* Write a description of the stream into array pointed by desc, which must be length bytes long.