Implement time-based resume and playback start.

This complements offset-based resume and playback start funcionality.
The implementation is global on both HWCODEC and SWCODEC.

Basically, if either the specified elapsed or offset are non-zero,
it indicates a mid-track resume.

To resume by time only, set elapsed to nonzero and offset to zero.
To resume by offset only, set offset to nonzero and elapsed to zero.

Which one the codec uses and which has priority is up to the codec;
however, using an elapsed time covers more cases:

* Codecs not able to use an offset such as VGM or other atomic
formats

* Starting playback at a nonzero elapsed time from a source that
contains no offset, such as a cuesheet

The change re-versions pretty much everything from tagcache to nvram.

Change-Id: Ic7aebb24e99a03ae99585c5e236eba960d163f38
Reviewed-on: http://gerrit.rockbox.org/516
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested: Michael Sevakis <jethead71@rockbox.org>

1 files changed, 12 insertions, 6 deletions

diff --git a/lib/rbcodec/codecs/mpc.c b/lib/rbcodec/codecs/mpc.c
index 9db40242dc..79f2aa22db 100644
--- a/lib/rbcodec/codecs/mpc.c
+++ b/lib/rbcodec/codecs/mpc.c
@@ -108,6 +108,7 @@ enum codec_status codec_run(void)
      * sample seek position from the file offset, the sampling frequency and
      * the bitrate. As the saved position is exactly calculated the reverse way 
      * there is no loss of information except rounding. */
+    elapsed_time = ci->id3->elapsed;
     samplesdone = 100 * (((mpc_uint64_t)ci->id3->offset * frequency) / byterate);
         
     /* Set up digital signal processing for correct number of channels */
@@ -122,19 +123,24 @@ enum codec_status codec_run(void)
     
     codec_set_replaygain(ci->id3);
 
-    /* Resume to saved sample offset. */
-    elapsed_time = 0;
-
-    if (samplesdone > 0) 
+    if (samplesdone > 0 || elapsed_time)
     {
-        if (mpc_demux_seek_sample(demux, samplesdone) == MPC_STATUS_OK) 
+        mpc_int64_t new_offset = samplesdone;
+
+        if (new_offset <= 0)
+            new_offset = (elapsed_time/10)*frequency; /* by time */
+
+        /* Resume to sample offset. */
+        if (mpc_demux_seek_sample(demux, new_offset) == MPC_STATUS_OK)
         {
-            elapsed_time = (samplesdone*10)/frequency;
+            samplesdone = new_offset;
         } 
         else 
         {
             samplesdone = 0;
         }
+
+        elapsed_time = (samplesdone*10)/frequency;
     }
 
     ci->set_elapsed(elapsed_time);