Fix FS#11103. Resuming musepack files was handled wrong since ages. This change converts the decoders exact sample position to an estimated byte position within the file. The resume position in samples is calculated the reverse way,

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25164 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 13 insertions, 6 deletions

diff --git a/apps/codecs/mpc.c b/apps/codecs/mpc.c
index b9ae558c67..afda2871f9 100644
--- a/apps/codecs/mpc.c
+++ b/apps/codecs/mpc.c
@@ -69,8 +69,9 @@ static mpc_bool_t canseek_impl(mpc_reader *reader)
 enum codec_status codec_main(void)
 {
     mpc_int64_t samplesdone;
-    uint32_t frequency; /* 0.1 kHz accuracy */
-    uint32_t elapsed_time; /* milliseconds */
+    uint32_t frequency;     /* 0.1 kHz accuracy */
+    uint32_t elapsed_time;  /* milliseconds */
+    uint32_t byterate;      /* bytes per second */
     mpc_status status;
     mpc_reader reader;
     mpc_streaminfo info;
@@ -102,8 +103,6 @@ next_track:
     while (!*ci->taginfo_ready && !ci->stop_codec)
         ci->sleep(1);
 
-    samplesdone = ci->id3->offset;
-
     /* initialize demux/decoder */
     demux = mpc_demux_init(&reader);
     if (NULL == demux)
@@ -114,9 +113,15 @@ next_track:
     /* read file's streaminfo data */
     mpc_demux_get_info(demux, &info);
     
-
+    byterate  = (mpc_uint32_t)(info.average_bitrate) / 8;
     frequency = info.sample_freq / 100; /* 0.1 kHz accuracy */
     ci->configure(DSP_SWITCH_FREQUENCY, info.sample_freq);
+
+    /* Remark: rockbox offset is the file offset in bytes. So, estimate the 
+     * 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. */
+    samplesdone = 100 * ((mpc_uint64_t)(ci->id3->offset * frequency) / byterate);
         
     /* set playback engine up for correct number of channels */
     /* NOTE: current musepack format only allows for stereo files
@@ -181,7 +186,9 @@ next_track:
             samplesdone += frame.samples;
             elapsed_time = (samplesdone*10)/frequency;
             ci->set_elapsed(elapsed_time);
-            ci->set_offset(samplesdone);
+            /* Remark: rockbox offset is the file offset in bytes. So estimate 
+             * this offset from the samples, sampling frequency and bitrate */
+            ci->set_offset( (samplesdone * byterate)/(frequency*100) );
         }
     } while (true);