Make libmusepack output the last frame in two passes. Reclaim the IRAM taken in the last commit. Please let me know if you can hear any artifacts or get any broken files from this!

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@9825 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 21 insertions, 14 deletions

diff --git a/apps/codecs/libmusepack/decoder.h b/apps/codecs/libmusepack/decoder.h
index 759670ee72..708533b09e 100644
--- a/apps/codecs/libmusepack/decoder.h
+++ b/apps/codecs/libmusepack/decoder.h
@@ -67,7 +67,7 @@ typedef struct mpc_decoder_t {
     mpc_uint32_t  Zaehler; /// actual index within read-buffer
 
     mpc_uint32_t  samples_to_skip;
-
+    mpc_uint32_t  last_block_samples;
     mpc_uint32_t  FwdJumpInfo;
     mpc_uint32_t  ActDecodePos;
     
diff --git a/apps/codecs/libmusepack/mpc_decoder.c b/apps/codecs/libmusepack/mpc_decoder.c
index 1291055327..ee98722a05 100644
--- a/apps/codecs/libmusepack/mpc_decoder.c
+++ b/apps/codecs/libmusepack/mpc_decoder.c
@@ -351,6 +351,21 @@ mpc_decoder_decode_internal(mpc_decoder *d, MPC_SAMPLE_FORMAT *buffer)
 
     mpc_uint32_t  FrameBitCnt = 0;
 
+    // output the last part of the last frame here, if needed
+    if (d->last_block_samples > 0) {
+        output_frame_length = d->last_block_samples;
+        d->last_block_samples = 0; // it's going to be handled now, so reset it 
+        if (!d->TrueGaplessPresent) {
+            mpc_decoder_reset_y(d);
+        } else {
+            mpc_decoder_bitstream_read(d, 20);
+            mpc_decoder_read_bitstream_sv7(d);
+            mpc_decoder_requantisierung(d, d->Max_Band);
+        }
+        mpc_decoder_synthese_filter_float(d, buffer);
+        return output_frame_length;
+    }
+    
     if (d->DecodedFrames >= d->OverallFrames) {
         return (mpc_uint32_t)(-1);                           // end of file -> abort decoding
     }
@@ -403,19 +418,10 @@ mpc_decoder_decode_internal(mpc_decoder *d, MPC_SAMPLE_FORMAT *buffer)
 
         // additional FilterDecay samples are needed for decay of synthesis filter
         if (MPC_DECODER_SYNTH_DELAY + mod_block >= MPC_FRAME_LENGTH) {
-            if (!d->TrueGaplessPresent) {
-                mpc_decoder_reset_y(d);
-            } else {
-                mpc_decoder_bitstream_read(d, 20);
-                mpc_decoder_read_bitstream_sv7(d);
-                mpc_decoder_requantisierung(d, d->Max_Band);
-            }
-
-            mpc_decoder_synthese_filter_float(d, buffer + 2304);
-
-            output_frame_length = MPC_FRAME_LENGTH + FilterDecay;
+            // this variable will be checked for at the top of the function
+            d->last_block_samples = FilterDecay;
         }
-        else {                              // there are only FilterDecay samples needed for this frame
+        else { // there are only FilterDecay samples needed for this frame
             output_frame_length = FilterDecay;
         }
     }
@@ -1173,6 +1179,7 @@ void mpc_decoder_setup(mpc_decoder *d, mpc_reader *r)
   d->OverallFrames = 0;
   d->DecodedFrames = 0;
   d->TrueGaplessPresent = 0;
+  d->last_block_samples = 0;
   d->WordsRead = 0;
   d->Max_Band = 0;
   d->SampleRate = 0;
diff --git a/apps/codecs/libmusepack/musepack.h b/apps/codecs/libmusepack/musepack.h
index d631c6d05d..9155f3f74d 100644
--- a/apps/codecs/libmusepack/musepack.h
+++ b/apps/codecs/libmusepack/musepack.h
@@ -58,7 +58,7 @@ extern "C" {
 
 enum {
     MPC_FRAME_LENGTH = (36 * 32),    /// samples per mpc frame
-    MPC_DECODER_BUFFER_LENGTH = 4 * MPC_FRAME_LENGTH /// required buffer size for decoder
+    MPC_DECODER_BUFFER_LENGTH = 2 * MPC_FRAME_LENGTH /// required buffer size for decoder
 };
 
 // error codes