Submit a patch to the VGM codec by Mauricio Gama which saves some more RAM through changes of the buffer configuration and an update of the resampler code. Additionally enable VGM for low memory targets and update the manual.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30327 a1c6a512-1295-4272-9138-f99709370657

5 files changed, 225 insertions, 342 deletions

diff --git a/apps/codecs/SOURCES b/apps/codecs/SOURCES
index 6862eed..db6e82c 100644
--- a/apps/codecs/SOURCES
+++ b/apps/codecs/SOURCES
@@ -37,8 +37,8 @@ gbs.c
 hes.c
 nsf.c
 sgc.c
-#if MEMORYSIZE > 2
 vgm.c
+#if MEMORYSIZE > 2
 kss.c
 #endif
 
diff --git a/apps/codecs/libgme/resampler.c b/apps/codecs/libgme/resampler.c
index a69a92c..e2e0734 100644
--- a/apps/codecs/libgme/resampler.c
+++ b/apps/codecs/libgme/resampler.c
@@ -25,294 +25,194 @@ enum { shift = 14 };
 int const unit = 1 << shift;
 
 blargg_err_t Resampler_setup( struct Resampler* this, int fm_rate, int fm_gain, int rate, int gain )
- {
-	this->gain_ = (int)( ((1LL << gain_bits) * fm_gain * gain) / FP_ONE_GAIN );
-	this->step  = (int)( ((1LL << shift) * fm_rate) / rate + 1);
-	this->rate_ = this->step;
- 	return 0;
- }
+{
+    this->gain_ = (int)( ((1LL << gain_bits) * fm_gain * gain) / FP_ONE_GAIN );
+    this->step  = (int)( ((1LL << shift) * fm_rate) / rate + 1);
+    this->rate_ = this->step;
+    return 0;
+}
 
 blargg_err_t Resampler_reset( struct Resampler* this, int pairs )
 {
-	// expand allocations a bit
-	Resampler_resize( this, pairs );
-	this->resampler_size = this->oversamples_per_frame + (this->oversamples_per_frame >> 2);
-
-	this->buffer_size = this->resampler_size;
-	this->pos = 0;
-	this->write_pos = 0;
-	return 0;
+    // expand allocations a bit
+    this->sample_buffer_size = (pairs + (pairs >> 2)) * 2;
+    Resampler_resize( this, pairs );
+    this->resampler_size = this->oversamples_per_frame + (this->oversamples_per_frame >> 2);
+
+    this->buffer_size = this->resampler_size;
+    this->pos = 0;
+    this->write_pos = 0;
+
+    Resampler_clear( this );
+    return 0;
 }
 
 void Resampler_resize( struct Resampler* this, int pairs )
 {
-	int new_sample_buf_size = pairs * 2;
-	if ( this->sample_buf_size != new_sample_buf_size )
-	{
-		this->sample_buf_size = new_sample_buf_size;
-		this->oversamples_per_frame = (int) ((pairs * this->rate_ * 2LL) / unit) + 2;
-		Resampler_clear( this );
-	}
+    int new_sample_buf_size = pairs * 2;
+    if ( this->sample_buf_size != new_sample_buf_size )
+    {
+        if ( new_sample_buf_size > this->sample_buffer_size )
+        {
+            check(false);
+            return;
+        }
+
+        this->sample_buf_size = new_sample_buf_size;
+        this->oversamples_per_frame = (int) ((pairs * this->rate_ * 2LL) / unit) + 2;
+        Resampler_clear( this );
+    }
 }
 
-static void mix_mono( struct Resampler* this, struct Stereo_Buffer* stereo_buf, dsample_t* out_ )
+void mix_samples( struct Resampler* this, struct Blip_Buffer* blip_buf, sample_t out_ [] )
 {
-	int const bass = BLIP_READER_BASS( stereo_buf->bufs [0] );
-	BLIP_READER_BEGIN( sn, stereo_buf->bufs [0] );
-	
-	int count = this->sample_buf_size >> 1;
-	BLIP_READER_ADJ_( sn, count );
-	
-	typedef dsample_t stereo_dsample_t [2];
-	stereo_dsample_t* BLARGG_RESTRICT out = (stereo_dsample_t*) out_ + count;
-	stereo_dsample_t const* BLARGG_RESTRICT in =
-			(stereo_dsample_t const*) this->sample_buf + count;
-	int offset = -count;
-	int const gain = this->gain_;
-	do
-	{
-		int s = BLIP_READER_READ_RAW( sn ) >> (blip_sample_bits - 16);
-		BLIP_READER_NEXT_IDX_( sn, bass, offset );
-		
-		int l = (in [offset] [0] * gain >> gain_bits) + s;
-		int r = (in [offset] [1] * gain >> gain_bits) + s;
-		
-		BLIP_CLAMP( l, l );
-		out [offset] [0] = (blip_sample_t) l;
-		
-		BLIP_CLAMP( r, r );
-		out [offset] [1] = (blip_sample_t) r;
-	}
-	while ( ++offset );
-	
-	BLIP_READER_END( sn, stereo_buf->bufs [0] );
+    int const bass = BLIP_READER_BASS( *blip_buf );
+    BLIP_READER_BEGIN( sn, *blip_buf );
+
+    int count = this->sample_buf_size >> 1;
+    BLIP_READER_ADJ_( sn, count );
+
+    typedef sample_t stereo_dsample_t [2];
+    stereo_dsample_t* BLARGG_RESTRICT out = (stereo_dsample_t*) out_ + count;
+    stereo_dsample_t const* BLARGG_RESTRICT in =
+        (stereo_dsample_t const*) this->sample_buf + count;
+    int offset = -count;
+    int const gain = this->gain_;
+    do
+    {
+        int s = BLIP_READER_READ_RAW( sn ) >> (blip_sample_bits - 16);
+        BLIP_READER_NEXT_IDX_( sn, bass, offset );
+
+        int l = (in [offset] [0] * gain >> gain_bits) + s;
+        int r = (in [offset] [1] * gain >> gain_bits) + s;
+
+        BLIP_CLAMP( l, l );
+        out [offset] [0] = (blip_sample_t) l;
+
+        BLIP_CLAMP( r, r );
+        out [offset] [1] = (blip_sample_t) r;
+    }
+    while ( ++offset );
+
+    BLIP_READER_END( sn, *blip_buf );
 }
 
-static void mix_stereo( struct Resampler* this, struct Stereo_Buffer* stereo_buf, dsample_t* out_ )
+sample_t const* resample_( struct Resampler* this, sample_t** out_,
+        sample_t const* out_end, sample_t const in [], int in_size )
 {
-	int const bass = BLIP_READER_BASS( stereo_buf->bufs [0] );
-	BLIP_READER_BEGIN( snc, stereo_buf->bufs [0] );
-	BLIP_READER_BEGIN( snl, stereo_buf->bufs [1] );
-	BLIP_READER_BEGIN( snr, stereo_buf->bufs [2] );
-	
-	int count = this->sample_buf_size >> 1;
-	BLIP_READER_ADJ_( snc, count );
-	BLIP_READER_ADJ_( snl, count );
-	BLIP_READER_ADJ_( snr, count );
-	
-	typedef dsample_t stereo_dsample_t [2];
-	stereo_dsample_t* BLARGG_RESTRICT out = (stereo_dsample_t*) out_ + count;
-	stereo_dsample_t const* BLARGG_RESTRICT in =
-			(stereo_dsample_t const*) this->sample_buf + count;
-	int offset = -count;
-	int const gain = this->gain_;
-	do
-	{
-		int sc = BLIP_READER_READ_RAW( snc ) >> (blip_sample_bits - 16);
-		int sl = BLIP_READER_READ_RAW( snl ) >> (blip_sample_bits - 16);
-		int sr = BLIP_READER_READ_RAW( snr ) >> (blip_sample_bits - 16);
-		BLIP_READER_NEXT_IDX_( snc, bass, offset );
-		BLIP_READER_NEXT_IDX_( snl, bass, offset );
-		BLIP_READER_NEXT_IDX_( snr, bass, offset );
-		
-		int l = (in [offset] [0] * gain >> gain_bits) + sl + sc;
-		int r = (in [offset] [1] * gain >> gain_bits) + sr + sc;
-		
-		BLIP_CLAMP( l, l );
-		out [offset] [0] = (blip_sample_t) l;
-		
-		BLIP_CLAMP( r, r );
-		out [offset] [1] = (blip_sample_t) r;
-	}
-	while ( ++offset );
-	
-	BLIP_READER_END( snc, stereo_buf->bufs [0] );
-	BLIP_READER_END( snl, stereo_buf->bufs [1] );
-	BLIP_READER_END( snr, stereo_buf->bufs [2] );
+    in_size -= write_offset;
+    if ( in_size > 0 )
+    {
+        sample_t* BLARGG_RESTRICT out = *out_;
+        sample_t const* const in_end = in + in_size;
+
+        int const step = this->step;
+        int       pos  = this->pos;
+
+        // TODO: IIR filter, then linear resample
+        // TODO: detect skipped sample, allowing merging of IIR and resample?
+
+        do
+        {
+            #define INTERP( i, out )\
+                out = (in [0 + i] * (unit - pos) + ((in [2 + i] + in [4 + i] + in [6 + i]) << shift) +\
+                in [8 + i] * pos) >> (shift + 2);
+
+            int out_0;
+            INTERP( 0,                  out_0 )
+            INTERP( 1, out [0] = out_0; out [1] )
+            out += stereo;
+
+            pos += step;
+            in += ((unsigned) pos >> shift) * stereo;
+            pos &= unit - 1;
+        }
+        while ( in < in_end && out < out_end );
+
+        this->pos = pos;
+        *out_ = out;
+    }
+    return in;
 }
 
-static void mix_stereo_no_center( struct Resampler* this, struct Stereo_Buffer* stereo_buf, dsample_t* out_ )
+inline int resample_wrapper( struct Resampler* this, sample_t out [], int* out_size,
+        sample_t const in [], int in_size )
 {
-	int const bass = BLIP_READER_BASS( stereo_buf->bufs [0] );
-	BLIP_READER_BEGIN( snl, stereo_buf->bufs [1] );
-	BLIP_READER_BEGIN( snr, stereo_buf->bufs [2] );
-	
-	int count = this->sample_buf_size >> 1;
-	BLIP_READER_ADJ_( snl, count );
-	BLIP_READER_ADJ_( snr, count );
-	
-	typedef dsample_t stereo_dsample_t [2];
-	stereo_dsample_t* BLARGG_RESTRICT out = (stereo_dsample_t*) out_ + count;
-	stereo_dsample_t const* BLARGG_RESTRICT in =
-			(stereo_dsample_t const*) this->sample_buf + count;
-	int offset = -count;
-	int const gain = this->gain_;
-	do
-	{
-		int sl = BLIP_READER_READ_RAW( snl ) >> (blip_sample_bits - 16);
-		int sr = BLIP_READER_READ_RAW( snr ) >> (blip_sample_bits - 16);
-		BLIP_READER_NEXT_IDX_( snl, bass, offset );
-		BLIP_READER_NEXT_IDX_( snr, bass, offset );
-		
-		int l = (in [offset] [0] * gain >> gain_bits) + sl;
-		int r = (in [offset] [1] * gain >> gain_bits) + sr;
-		
-		BLIP_CLAMP( l, l );
-		out [offset] [0] = (blip_sample_t) l;
-		
-		BLIP_CLAMP( r, r );
-		out [offset] [1] = (blip_sample_t) r;
-	}
-	while ( ++offset );
-	
-	BLIP_READER_END( snl, stereo_buf->bufs [1] );
-	BLIP_READER_END( snr, stereo_buf->bufs [2] );
-}
+    assert( Resampler_rate( this ) );
 
-static dsample_t const* resample_( struct Resampler* this, dsample_t** out_,
-		dsample_t const* out_end, dsample_t const in [], int in_size )
-{
-	in_size -= write_offset;
-	if ( in_size > 0 )
-	{
-		dsample_t* BLIP_RESTRICT out = *out_;
-		dsample_t const* const in_end = in + in_size;
-		
-		int const step = this->step;
-		int       pos  = this->pos;
-		
-		// TODO: IIR filter, then linear resample
-		// TODO: detect skipped sample, allowing merging of IIR and resample?
-		
-		do
-		{
-			#define INTERP( i, out )\
-				out = (in [0 + i] * (unit - pos) + ((in [2 + i] + in [4 + i] + in [6 + i]) << shift) +\
-				in [8 + i] * pos) >> (shift + 2);
-			
-			int out_0;
-			INTERP( 0,                  out_0 )
-			INTERP( 1, out [0] = out_0; out [1] )
-			out += stereo;
-			
-			pos += step;
-			in += ((unsigned) pos >> shift) * stereo;
-			pos &= unit - 1;
-		}
-		while ( in < in_end && out < out_end );
-		
-		this->pos = pos;
-		*out_ = out;
-	}
-	return in;
-}
+    sample_t* out_ = out;
+    int result = resample_( this, &out_, out + *out_size, in, in_size ) - in;
+    assert( out_ <= out + *out_size );
+    assert( result <= in_size );
 
-static inline int resample_wrapper( struct Resampler* this, dsample_t out [], int* out_size,
-		dsample_t const in [], int in_size )
-{
-	assert( Resampler_rate( this ) );
-	
-	dsample_t* out_ = out;
-	int result = resample_( this, &out_, out + *out_size, in, in_size ) - in;
-	assert( out_ <= out + *out_size );
-	assert( result <= in_size );
-	
-	*out_size = out_ - out;
-	return result;
+    *out_size = out_ - out;
+    return result;
 }
 
-static int skip_input( struct Resampler* this, int count )
+int skip_input( struct Resampler* this, int count )
 {
-	this->write_pos -= count;
-	if ( this->write_pos < 0 ) // occurs when downsampling
-	{
-		count += this->write_pos;
-		this->write_pos = 0;
-	}
-	memmove( this->buf, &this->buf [count], this->write_pos * sizeof this->buf [0] );
-	return count;
+    this->write_pos -= count;
+    if ( this->write_pos < 0 ) // occurs when downsampling
+    {
+        count += this->write_pos;
+        this->write_pos = 0;
+    }
+    memmove( this->buf, &this->buf [count], this->write_pos * sizeof this->buf [0] );
+    return count;
 }
 
-static void play_frame_( struct Resampler* this, struct Stereo_Buffer* stereo_buf, dsample_t* out )
+void play_frame_( struct Resampler* this, struct Blip_Buffer* blip_buf, sample_t* out )
 {
-	long pair_count = this->sample_buf_size >> 1;
-	blip_time_t blip_time = Blip_count_clocks( &stereo_buf->bufs [0], pair_count );
-	int sample_count = this->oversamples_per_frame - this->write_pos + resampler_extra;
-	
-	int new_count = this->callback( this->callback_data, blip_time, sample_count, &this->buf [this->write_pos] );
-	assert( new_count < resampler_size );
-	
-	Buffer_end_frame( stereo_buf, blip_time );
-	/* Blip_end_frame( &stereo_buf->bufs [0], blip_time ); */
-	assert( Blip_samples_avail( &stereo_buf->bufs [0] ) == pair_count * 2 );
-	
-	this->write_pos += new_count;
-	assert( (unsigned) this->write_pos <= this->buffer_size );
-	
-	new_count = this->sample_buf_size;
-	if ( new_count )
-		skip_input( this, resample_wrapper( this, this->sample_buf, &new_count, this->buf, this->write_pos ) );
-	assert( new_count == (long) this->sample_buf_size );
-	
-	int bufs_used = stereo_buf->stereo_added | stereo_buf->was_stereo;
-	if ( bufs_used <= 1 ) {
-		mix_mono( this, stereo_buf, out );
-		Blip_remove_samples( &stereo_buf->bufs [0], pair_count );
-		Blip_remove_silence( &stereo_buf->bufs [1], pair_count );
-		Blip_remove_silence( &stereo_buf->bufs [2], pair_count );
-	}
-	else if ( bufs_used & 1 ) {
-		mix_stereo( this, stereo_buf, out );
-		Blip_remove_samples( &stereo_buf->bufs [0], pair_count );
-		Blip_remove_samples( &stereo_buf->bufs [1], pair_count );
-		Blip_remove_samples( &stereo_buf->bufs [2], pair_count );
-	}
-	else {
-		mix_stereo_no_center( this, stereo_buf, out );
-		Blip_remove_silence( &stereo_buf->bufs [0], pair_count );
-		Blip_remove_samples( &stereo_buf->bufs [1], pair_count );
-		Blip_remove_samples( &stereo_buf->bufs [2], pair_count );
-	}
-	
-	// to do: this might miss opportunities for optimization
-	if ( !Blip_samples_avail( &stereo_buf->bufs [0] ) )
-	{
-		stereo_buf->was_stereo   = stereo_buf->stereo_added;
-		stereo_buf->stereo_added = 0;
-	}
-	
-	/* mix_mono( this, stereo_buf, out );
-	Blip_remove_samples( &stereo_buf->bufs [0], pair_count ); */
+    int pair_count = this->sample_buf_size >> 1;
+    blip_time_t blip_time = Blip_count_clocks( blip_buf, pair_count );
+    int sample_count = this->oversamples_per_frame - this->write_pos + resampler_extra;
+
+    int new_count = this->callback( this->callback_data, blip_time, sample_count, &this->buf [this->write_pos] );
+    assert( new_count < this->resampler_size );
+
+    Blip_end_frame( blip_buf, blip_time );
+    assert( Blip_samples_avail( blip_buf ) == pair_count );
+
+    this->write_pos += new_count;
+    assert( (unsigned) this->write_pos <= this->buffer_size );
+
+    int count = this->sample_buf_size;
+    if ( count )
+        skip_input( this, resample_wrapper( this, this->sample_buf, &count, this->buf, this->write_pos ) );
+    assert( count == this->sample_buf_size );
+
+    mix_samples( this, blip_buf, out );
+    Blip_remove_samples( blip_buf, pair_count );
 }
 
-void Resampler_play( struct Resampler* this, long count, dsample_t* out, struct Stereo_Buffer* stereo_buf )
+void Resampler_play( struct Resampler* this, int count, sample_t* out, struct Blip_Buffer* blip_buf )
 {
-	// empty extra buffer
-	long remain = this->sample_buf_size - this->buf_pos;
-	if ( remain )
-	{
-		if ( remain > count )
-			remain = count;
-		count -= remain;
-		memcpy( out, &this->sample_buf [this->buf_pos], remain * sizeof *out );
-		out += remain;
-		this->buf_pos += remain;
-	}
-	
-	// entire frames
-	while ( count >= (long) this->sample_buf_size )
-	{
-		play_frame_( this, stereo_buf, out );
-		out += this->sample_buf_size;
-		count -= this->sample_buf_size;
-	}
-	
-	// extra
-	if ( count )
-	{
-		play_frame_( this, stereo_buf, this->sample_buf );
-		this->buf_pos = count;
-		memcpy( out, this->sample_buf, count * sizeof *out );
-		out += count;
-	}
+    // empty extra buffer
+    int remain = this->sample_buf_size - this->buf_pos;
+    if ( remain )
+    {
+        if ( remain > count )
+            remain = count;
+        count -= remain;
+        memcpy( out, &this->sample_buf [this->buf_pos], remain * sizeof *out );
+        out += remain;
+        this->buf_pos += remain;
+    }
+
+    // entire frames
+    while ( count >= this->sample_buf_size )
+    {
+        play_frame_( this, blip_buf, out );
+        out += this->sample_buf_size;
+        count -= this->sample_buf_size;
+    }
+
+    // extra
+    if ( count )
+    {
+        play_frame_( this, blip_buf, this->sample_buf );
+        this->buf_pos = count;
+        memcpy( out, this->sample_buf, count * sizeof *out );
+        out += count;
+    }
 }
diff --git a/apps/codecs/libgme/resampler.h b/apps/codecs/libgme/resampler.h
index 3106b84..1d8f866 100644
--- a/apps/codecs/libgme/resampler.h
+++ b/apps/codecs/libgme/resampler.h
@@ -4,10 +4,10 @@
 #ifndef RESAMPLER_H
 #define RESAMPLER_H
 
-#include "blargg_config.h"
+#include "blargg_common.h"
 #include "multi_buffer.h"
 
-typedef short dsample_t;
+typedef short sample_t;
 
 enum { stereo = 2 };
 enum { max_buf_size = 3960 };
@@ -15,54 +15,62 @@ enum { max_resampler_size = 5942 };
 enum { write_offset = 8 * stereo };
 enum { gain_bits = 14 };
 
-struct Resampler {		
-	int (*callback)( void*, blip_time_t, int, dsample_t* );
-	void* callback_data;
-	
-	dsample_t sample_buf [max_buf_size];
-	int sample_buf_size;
-	int oversamples_per_frame;
-	int buf_pos;
-	int resampler_size;
-	int gain_;
-	
-	// Internal resampler
-	dsample_t buf [max_resampler_size];
-	int buffer_size;
-	
-	int write_pos;
-	int rate_;
-	
-	int pos;
-	int step;
+struct Resampler {
+    int (*callback)( void*, blip_time_t, int, sample_t* );
+    void* callback_data;
+
+    int sample_buffer_size;
+    int sample_buf_size;
+    int oversamples_per_frame;
+    int buf_pos;
+    int resampler_size;
+    int gain_;
+
+    int buffer_size;
+    int write_pos;
+
+    int pos;
+    int step;
+
+    int rate_;
+
+    sample_t sample_buf [max_buf_size];
+    sample_t buf [max_resampler_size];   // Internal resampler
 };
 
 static inline void Resampler_init( struct Resampler* this )
 {
-	this->pos = 0;
-	this->write_pos = 0;
-	this->rate_     = 0;
+    this->pos = 0;
+    this->write_pos = 0;
+    this->rate_     = 0;
+    this->sample_buf_size = 0;
+    this->sample_buffer_size = 0;
+    this->oversamples_per_frame = 0;
 }
 
 blargg_err_t Resampler_reset( struct Resampler* this, int max_pairs );
 void Resampler_resize( struct Resampler* this, int pairs_per_frame );
-	
-void Resampler_play( struct Resampler* this, long count, dsample_t* out, struct Stereo_Buffer* );
+void Resampler_play( struct Resampler* this, int count, sample_t* out, struct Blip_Buffer* );
 
-static inline void Resampler_set_callback(struct Resampler* this, int (*func)( void*, blip_time_t, int, dsample_t* ), void* user_data )
+static inline void Resampler_set_callback(struct Resampler* this, int (*func)( void*, blip_time_t, int, sample_t* ), void* user_data )
 {
-	this->callback = func;
-	this->callback_data = user_data;
+    this->callback = func;
+    this->callback_data = user_data;
 }
 
 blargg_err_t Resampler_setup( struct Resampler* this, int fm_rate, int fm_gain, int rate, int gain );
 
 static inline void Resampler_clear( struct Resampler* this )
 {
-	this->buf_pos = this->sample_buf_size;
+    this->buf_pos = this->sample_buf_size;
+
+    this->pos = 0;
+    this->write_pos = 0;
+}
 
-	this->pos = 0;
-	this->write_pos = 0;
+static inline int Resampler_rate( struct Resampler* this )
+{
+    return this->rate_;
 }
 
 #endif
diff --git a/apps/codecs/libgme/vgm_emu.c b/apps/codecs/libgme/vgm_emu.c
index d599056..391bd02 100644
--- a/apps/codecs/libgme/vgm_emu.c
+++ b/apps/codecs/libgme/vgm_emu.c
@@ -89,8 +89,7 @@ void Vgm_init( struct Vgm_Emu* this )
 	Synth_init( &this->pcm );
 	
 	Buffer_init( &this->buf );
-	Buffer_init( &this->stereo_buf );
-	this->blip_buf = &this->stereo_buf.bufs [0];
+	Blip_init( &this->blip_buf );
 
 	// Init fm chips	
 	Ym2413_init( &this->ym2413 );
@@ -279,7 +278,7 @@ blargg_err_t Vgm_load_mem( struct Vgm_Emu* this, byte const* new_data, long new_
 	if ( !this->psg_rate )
 		this->psg_rate = 3579545;
 	
-	Buffer_clock_rate( &this->stereo_buf, this->psg_rate );
+	Blip_set_clock_rate( &this->blip_buf, this->psg_rate );
 	
 	// Disable FM
 	this->fm_rate = 0;
@@ -342,14 +341,14 @@ blargg_err_t setup_fm( struct Vgm_Emu* this )
 {
 	int fm_rate = 0;
 	if ( !this->disable_oversampling )
-		this->fm_rate = (this->sample_rate * 3) / 2; // oversample factor = 1.5
+		fm_rate = (this->sample_rate * 3) / 2; // oversample factor = 1.5
 	RETURN_ERR( init_fm( this, &fm_rate ) );
 	
 	if ( uses_fm( this ) )
 	{
 		this->voice_count = 8;
 		RETURN_ERR( Resampler_setup( &this->resampler, fm_rate, fm_gain, this->sample_rate, this->gain ) );
-		RETURN_ERR( Resampler_reset( &this->resampler, Buffer_length( &this->stereo_buf ) * this->sample_rate / 1000 ) );
+		RETURN_ERR( Resampler_reset( &this->resampler, Blip_length( &this->blip_buf ) * this->sample_rate / 1000 ) );
 		Sms_apu_volume( &this->psg, ((this->gain/5)-(this->gain*5)/1000) * fm_gain );
 	}
 	else
@@ -399,7 +398,7 @@ static blargg_err_t play_( struct Vgm_Emu* this, long count, sample_t* out )
 		return 0;
 	}
 		
-	Resampler_play( &this->resampler, count, out, &this->stereo_buf );
+	Resampler_play( &this->resampler, count, out, &this->blip_buf );
 	return 0;
 }
 
@@ -428,19 +427,16 @@ static inline blip_time_t to_psg_time( struct Vgm_Emu* this, vgm_time_t t )
 
 static void write_pcm( struct Vgm_Emu* this, vgm_time_t vgm_time, int amp )
 {
-	if ( this->blip_buf )
-	{
-		check( amp >= 0 );
-		blip_time_t blip_time = to_psg_time( this, vgm_time );
-		int old = this->dac_amp;
-		int delta = amp - old;
-		this->dac_amp = amp;
-		Blip_set_modified( this->blip_buf );
-		if ( old >= 0 ) // first write is ignored, to avoid click
-			Synth_offset_inline( &this->pcm, blip_time, delta, this->blip_buf );
-		else
-			this->dac_amp |= this->dac_disabled;
-	}
+	check( amp >= 0 );
+	blip_time_t blip_time = to_psg_time( this, vgm_time );
+	int old = this->dac_amp;
+	int delta = amp - old;
+	this->dac_amp = amp;
+	Blip_set_modified( &this->blip_buf );
+	if ( old >= 0 ) // first write is ignored, to avoid click
+		Synth_offset_inline( &this->pcm, blip_time, delta, &this->blip_buf );
+	else
+		this->dac_amp |= this->dac_disabled;
 }
 
 blip_time_t run( struct Vgm_Emu* this, vgm_time_t end_time )
@@ -514,22 +510,7 @@ blip_time_t run( struct Vgm_Emu* this, vgm_time_t end_time )
 		
 		case cmd_ym2612_port1:
 			if ( Ym2612_run_until( &this->ym2612, to_fm_time( this, vgm_time ) ) )
-			{
-				if ( pos [0] == ym2612_dac_pan_port )
-				{
-					struct Blip_Buffer* blip_buf = NULL;
-					switch ( pos [1] >> 6 )
-					{
-					case 0: blip_buf = NULL; break;
-					case 1: blip_buf = &this->stereo_buf.bufs [2]; break;
-					case 2: blip_buf = &this->stereo_buf.bufs [1]; break;
-					case 3: blip_buf = &this->stereo_buf.bufs [0]; break;
-					}
-					this->blip_buf = blip_buf;
-				}
-			
 				Ym2612_write1( &this->ym2612, pos [0], pos [1] );
-			}
 			pos += 2;
 			break;
 			
@@ -664,7 +645,7 @@ void update_fm_rates( struct Vgm_Emu* this, int* ym2413_rate, int* ym2612_rate )
 blargg_err_t Vgm_set_sample_rate( struct Vgm_Emu* this, long rate )
 {
 	require( !this->sample_rate ); // sample rate can't be changed once set
-	RETURN_ERR( Buffer_set_sample_rate( &this->stereo_buf, rate, 1000 / 30 ) );
+	RETURN_ERR( Blip_set_sample_rate( &this->blip_buf, rate, 1000 / 30 ) );
 	RETURN_ERR( Buffer_set_sample_rate( &this->buf, rate, 1000 / 20 ) );
 	
 	// Set bass frequency
@@ -712,7 +693,7 @@ void Sound_mute_voices( struct Vgm_Emu* this, int mask )
 	if ( uses_fm( this ) )
 	{
 		for ( i = sms_osc_count; --i >= 0; )
-			Sms_apu_set_output( &this->psg, i, ( mask & 0x80 ) ? 0 : &this->stereo_buf.bufs [0], NULL, NULL );
+			Sms_apu_set_output( &this->psg, i, ( mask & 0x80 ) ? 0 : &this->blip_buf, NULL, NULL );
 		if ( Ym2612_enabled( &this->ym2612 ) )
 		{
 			Synth_volume( &this->pcm, (mask & 0x40) ? 0 : (int)((long long)(0.1115*FP_ONE_VOLUME) / 256 * fm_gain * this->gain / FP_ONE_VOLUME) );
@@ -743,7 +724,7 @@ void Sound_set_tempo( struct Vgm_Emu* this, int t )
 	if ( this->file_begin )
 	{
 		this->vgm_rate = (long) ((44100LL * t) / FP_ONE_TEMPO);
-		this->blip_time_factor = (int) (((1LL << blip_time_bits) * Blip_clock_rate( &this->stereo_buf.bufs [0] )) / this->vgm_rate);
+		this->blip_time_factor = (int) (((1LL << blip_time_bits) * Blip_clock_rate( &this->blip_buf )) / this->vgm_rate);
 		//debug_printf( "blip_time_factor: %ld\n", blip_time_factor );
 		//debug_printf( "vgm_rate: %ld\n", vgm_rate );
 		// TODO: remove? calculates vgm_rate more accurately (above differs at most by one Hz only)
@@ -761,8 +742,6 @@ blargg_err_t Vgm_start_track( struct Vgm_Emu* this )
 	
 	Sms_apu_reset( &this->psg, get_le16( header( this )->noise_feedback ), header( this )->noise_width );
 	
-	this->blip_buf = &this->stereo_buf.bufs [0];
-	
 	this->dac_disabled = -1;
 	this->pos          = this->file_begin + header_size;
 	this->pcm_data     = this->pos;
@@ -785,7 +764,7 @@ blargg_err_t Vgm_start_track( struct Vgm_Emu* this )
 		if ( Ym2612_enabled( &this->ym2612 ) )
 			Ym2612_reset( &this->ym2612 );
 		
-		Buffer_clear( &this->stereo_buf );
+		Blip_clear( &this->blip_buf, 1 );
 		Resampler_clear( &this->resampler );
 	}
 	
diff --git a/apps/codecs/libgme/vgm_emu.h b/apps/codecs/libgme/vgm_emu.h
index bc04086..773b850 100644
--- a/apps/codecs/libgme/vgm_emu.h
+++ b/apps/codecs/libgme/vgm_emu.h
@@ -12,7 +12,6 @@
 #include "ym2612_emu.h"
 #include "sms_apu.h"
 
-typedef short sample_t;
 typedef int vgm_time_t;
 typedef int fm_time_t;
 
@@ -85,7 +84,7 @@ struct Vgm_Emu {
 	int dac_amp;
 	int dac_disabled; // -1 if disabled
 
-	struct Blip_Buffer* blip_buf;
+	struct Blip_Buffer blip_buf;
 
 	// general
 	long clock_rate_;
@@ -124,10 +123,7 @@ struct Vgm_Emu {
 	
 	struct Sms_Apu psg;
 	struct Blip_Synth pcm;
-	struct Stereo_Buffer stereo_buf;
-	
 	struct Resampler resampler;
-	
 	struct Stereo_Buffer buf;
 };