Commit work started in FS#12153 to put timing/position information in PCM

buffer chunks.

* Samples and position indication is closely associated with audio data
  instead of compensating by a latency constant. Alleviates problems with
  using the elapsed as a track indicator where it could be off by several
  steps.

* Timing is accurate throughout track even if resampling for pitch shift,
  whereas before it updated during transition latency at the normal 1:1 rate.

* Simpler PCM buffer with a constant chunk size, no linked lists.

In converting crossfade, a minor change was made to not change the WPS until
the fade-in of the incoming track, whereas before it would change upon the
start of the fade-out of the outgoing track possibly having the WPS change
with far too much lead time.

Codec changes are to set elapsed times *before* writing next PCM frame because
 time and position data last set are saved in the next committed PCM chunk. 


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30366 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 7 insertions, 5 deletions

diff --git a/apps/codecs/mpa.c b/apps/codecs/mpa.c
index c9e2131450..ac81f06cab 100644
--- a/apps/codecs/mpa.c
+++ b/apps/codecs/mpa.c
@@ -144,6 +144,7 @@ static void set_elapsed(struct mp3entry* id3)
 {
     unsigned long offset = id3->offset > id3->first_frame_offset ?
         id3->offset - id3->first_frame_offset : 0;
+    unsigned long elapsed = id3->elapsed;
 
     if ( id3->vbr ) {
         if ( id3->has_toc ) {
@@ -172,27 +173,28 @@ static void set_elapsed(struct mp3entry* id3)
             /* set time for this percent (divide before multiply to prevent
                overflow on long files. loss of precision is negligible on
                short files) */
-            id3->elapsed = i * (id3->length / 100);
+            elapsed = i * (id3->length / 100);
 
             /* calculate remainder time */
             plen = (nextpos - relpos) * (id3->filesize / 256);
-            id3->elapsed += (((remainder * 100) / plen) *
-                             (id3->length / 10000));
+            elapsed += (((remainder * 100) / plen) * (id3->length / 10000));
         }
         else {
             /* no TOC exists. set a rough estimate using average bitrate */
             int tpk = id3->length /
                 ((id3->filesize - id3->first_frame_offset - id3->id3v1len) /
                 1024);
-            id3->elapsed = offset / 1024 * tpk;
+            elapsed = offset / 1024 * tpk;
         }
     }
     else
     {
         /* constant bitrate, use exact calculation */
         if (id3->bitrate != 0)
-            id3->elapsed = offset / (id3->bitrate / 8);
+            elapsed = offset / (id3->bitrate / 8);
     }
+
+    ci->set_elapsed(elapsed);
 }
 
 #ifdef MPA_SYNTH_ON_COP