diff --git a/configure.ac b/configure.ac
index 7401091..450b10d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 AC_PREREQ([2.61])
-AC_INIT([liba8cas], [1.5.0],,,[http://a8cas.sourceforge.net/])
+AC_INIT([liba8cas], [1.5.1],,,[http://a8cas.sourceforge.net/])
 
 # foreign, because we don't have a ChangeLog file
 AM_INIT_AUTOMAKE([foreign silent-rules])
diff --git a/include/a8cas.h b/include/a8cas.h
index 4992867..be7c845 100644
--- a/include/a8cas.h
+++ b/include/a8cas.h
@@ -181,6 +181,8 @@ A8CAS_API int A8CAS_read_audio(A8CAS_FILE *file, void *samples, unsigned int num
 
 A8CAS_API int A8CAS_write_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples);
 
+A8CAS_API int A8CAS_write_with_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples, unsigned int *audio_samples);
+
 /* ---- Block-navigation functions ---- */
 
 /* Returns current block/sample number (counted from 0). */
@@ -231,7 +233,8 @@ typedef enum A8CAS_param {
 	A8CAS_PARAM_SILENCE_LEVEL, /* Value type: float */
 	A8CAS_PARAM_CROSSTALK_VOLUME, /* Value type: float */
 	A8CAS_PARAM_MIN_BAUDRATE, /* Value type: unsigned int */
-	A8CAS_PARAM_MAX_BAUDRATE /* Value type: unsigned int */
+	A8CAS_PARAM_MAX_BAUDRATE, /* Value type: unsigned int */
+	A8CAS_PARAM_PWM_ENCODE /* Value type: int */
 } A8CAS_param;
 
 /* Returns 0 on success, else call A8CAS_error() to get an error code:
diff --git a/src/a8cas.c b/src/a8cas.c
index ee9d303..f21077a 100644
--- a/src/a8cas.c
+++ b/src/a8cas.c
@@ -173,8 +173,16 @@ int A8CAS_write(A8CAS_FILE *file, A8CAS_signal const *sig)
 	return (*file->write_func)(file, sig);
 }
 
+/* Deprecated */
 int A8CAS_write_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples)
 {
+	unsigned int dummy_number;
+
+	return A8CAS_write_with_audio(file, sig, samples, &dummy_number);
+}
+
+int A8CAS_write_with_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples, unsigned int *audio_samples)
+{
 	/* Signals of length 0 cause problems in CAS_ENCODE. So they are
 	   ignored a bit earlier. */
 	if (sig->length == 0)
@@ -187,7 +195,7 @@ int A8CAS_write_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples)
 	case A8CAS_FORMAT_FSK:
 		return FORMAT_FSK_write_audio(file, sig, samples);
 	case A8CAS_FORMAT_SNDFILE:
-		return FORMAT_SNDFILE_write_audio(file, sig, samples);
+		return FORMAT_SNDFILE_write_with_audio(file, sig, samples, audio_samples);
 	default: /* case A8CAS_FORMAT_RAW */
 		return FORMAT_RAW_write_audio(file, sig, samples);
 	}
@@ -440,6 +448,11 @@ int A8CAS_switch_PWM_decoding(A8CAS_FILE *file, int on)
 	return A8CAS_set_param(file, A8CAS_PARAM_PWM_DECODE, &on);
 }
 
+int A8CAS_switch_PWM_encoding(A8CAS_FILE *file, int on)
+{
+	return A8CAS_set_param(file, A8CAS_PARAM_PWM_ENCODE, &on);
+}
+
 int A8CAS_set_PWM_tolerance(A8CAS_FILE *file, unsigned short int tolerance)
 {
 	return A8CAS_set_param(file, A8CAS_PARAM_PWM_TOLERANCE, &tolerance);
diff --git a/src/cas_decode.c b/src/cas_decode.c
index 01d5aee..435db48 100644
--- a/src/cas_decode.c
+++ b/src/cas_decode.c
@@ -405,7 +405,7 @@ unsigned int CAS_DECODE_read_signals(CAS_DECODE_t *decode, A8CAS_signal *sigs, u
 		
 		{
 			if ((*decode->read_func)(decode, &sigs[written++]) != 0);
-				return 0;
+			return 0;
 		}
 	}
 }
diff --git a/src/cas_encode.h b/src/cas_encode.h
index 28c1f73..f0166eb 100644
--- a/src/cas_encode.h
+++ b/src/cas_encode.h
@@ -26,6 +26,8 @@
 #include "a8cas.h"
 #include "pokey_deserialize.h"
 
+#include "pwm.h"
+
 enum { CAS_ENCODE_DATA_BUF_SIZE = 65535 };
 
 /* CAS_ENCODE_FSK_BUF_SIZE must be an odd number. */
@@ -64,6 +66,11 @@ struct CAS_ENCODE_t {
 
 	int (*process_byte_func)(CAS_ENCODE_t*, uint8_t, double);
 	int (*process_signal_func)(CAS_ENCODE_t*, uint8_t, double);
+
+	int (*write_pwms_block_func)(A8CAS_FILE*, uint16_t, int, int);
+	int (*write_pwmd_block_func)(A8CAS_FILE*, unsigned int, unsigned int, uint8_t const *, uint16_t);
+	int (*write_pwmc_block_func)(A8CAS_FILE*, uint16_t, pwmc_buffer *, uint16_t);
+	int (*write_pwml_block_func)(A8CAS_FILE*, uint16_t, uint16_t *, uint16_t);
 };
 
 /* Sets default values for encode adjustments */
diff --git a/src/format_cas.c b/src/format_cas.c
index 3c5767b..de5cfe0 100644
--- a/src/format_cas.c
+++ b/src/format_cas.c
@@ -37,6 +37,7 @@
 #include "format_stdio_based.h"
 #include "io.h"
 #include "read_audio.h"
+#include "pwm.h"
 
 /*#define REPORT_BLOCKS*/
 
@@ -475,6 +476,24 @@ static int write_baud_block(A8CAS_FILE *file, uint16_t baudrate)
 	return write_cas_header(file, &header);
 }
 
+static int write_pwms_block(A8CAS_FILE *file, uint16_t rate, int lsb_first, int rising_edge_first)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	CAS_HEADER_t header;
+	int result;
+	header.type = BLOCK_TYPE_PWMS;
+	header.length = 2;
+	header.aux = (lsb_first << 2) + (rising_edge_first ? 2 : 1);
+	result = write_cas_header(file, &header);
+	if (result != 0)
+		return 1;
+	if (fwrite(&rate, sizeof(uint16_t), 1, data->file) != 1) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	return result;
+}
+
 static int write_data_block(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const *buffer, uint16_t length)
 {
 	file_specific *data = (file_specific*) file->specific_data;
@@ -492,12 +511,29 @@ static int write_data_block(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const *bu
 	return 0;
 }
 
-static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+static int write_pwmd_block(A8CAS_FILE *file, unsigned int length_0, unsigned int length_1, uint8_t const *buffer, uint16_t length)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	CAS_HEADER_t header;
+	header.type = BLOCK_TYPE_PWMD;
+	header.length = length;
+	header.aux = length_0 + (length_1 << 8);
+	if (write_cas_header(file, &header) != 0)
+		return 1;
+
+	if (fwrite(buffer, sizeof(uint8_t), length, data->file) != length) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	return 0;
+}
+
+static int write_various_signals__block(A8CAS_FILE *file, uint32_t type, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
 {
 	file_specific *data = (file_specific*) file->specific_data;
 	CAS_HEADER_t header;
 	int i;
-	header.type = BLOCK_TYPE_FSK;
+	header.type = type;
 	header.length = length * 2;
 	header.aux = irg_ms;
 	if (write_cas_header(file, &header) != 0)
@@ -514,6 +550,38 @@ static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer,
 	return 0;
 }
 
+static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+{
+	return write_various_signals__block(file, BLOCK_TYPE_FSK, irg_ms, buffer, length);
+}
+
+static int write_pwmc_block(A8CAS_FILE *file, uint16_t irg_ms, pwmc_buffer *buffer, uint16_t length)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	CAS_HEADER_t header;
+	int i;
+	header.type = BLOCK_TYPE_PWMC;
+	header.length = length * 3;
+	header.aux = irg_ms;
+	if (write_cas_header(file, &header) != 0)
+		return 1;
+
+	/* Convert the buffer to proper endianness. */
+	for (i = 0; i < length; i += 2)
+		buffer[i+1] = LE_SHORT(buffer[i+1]);
+
+	if (fwrite(buffer, sizeof(uint8_t) + sizeof(uint16_t), length, data->file) != length) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	return 0;
+}
+
+static int write_pwml_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+{
+	return write_various_signals__block(file, BLOCK_TYPE_PWMC, irg_ms, buffer, length);
+}
+
 /* ------------------------------------------------------------------------ *
  * Write functions                                                          *
  * ------------------------------------------------------------------------ */
@@ -896,6 +964,10 @@ int FORMAT_CAS_open(A8CAS_FILE *file, char const *path, A8CAS_info *info)
 	data->cas_encode.write_baud_block_func = &write_baud_block;
 	data->cas_encode.write_data_block_func = &write_data_block;
 	data->cas_encode.write_fsk_block_func = &write_fsk_block;
+	data->cas_encode.write_pwms_block_func = &write_pwms_block;
+	data->cas_encode.write_pwmd_block_func = &write_pwmd_block;
+	data->cas_encode.write_pwmc_block_func = &write_pwmc_block;
+	data->cas_encode.write_pwml_block_func = &write_pwml_block;
 	data->cas_encode.add_block_offset_func = &add_offset_after_write_block;
 
 	/*data->read_audio.mod_type = MOD_TYPE_FSK;*/
diff --git a/src/format_hex.c b/src/format_hex.c
index c5403b0..8f71d55 100644
--- a/src/format_hex.c
+++ b/src/format_hex.c
@@ -38,6 +38,7 @@
 #include "format_stdio_based.h"
 #include "io.h"
 #include "read_audio.h"
+#include "pwm.h"
 
 #define READ_BUF_SIZE 16
 #define FSCANF_BUF_SIZE 21
@@ -546,6 +547,19 @@ static int write_baud_block(A8CAS_FILE *file, uint16_t baudrate)
 	return 0;
 }
 
+static int write_pwms_block(A8CAS_FILE *file, uint16_t rate, int lsb_first, int rising_edge_first)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	if (fprintf(data->file, "pwms %s %s %05u\n",
+		    lsb_first ? "lsb_first" : "msb_first",
+		    rising_edge_first ? "rising_edge_first" : "falling_edge_first",
+		    (unsigned int)rate) < 0) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	return 0;
+}
+
 static int write_data_block_bytes(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const *buffer, uint16_t length)
 {
 	file_specific *data = (file_specific*) file->specific_data;
@@ -600,6 +614,44 @@ static int write_standard_block(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const
 	return 0;
 }
 
+static int write_pwmd_block_bytes(A8CAS_FILE *file, unsigned int length_0, unsigned int length_1, uint8_t const *buffer, uint16_t length)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	unsigned int i;
+
+	if (fprintf(data->file, "pwmd %u %u", (unsigned int)length_0, (unsigned int)length_1) < 0) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	for(i = 0; i < length; i ++) {
+		if (fprintf(data->file, " %02x", (unsigned int)buffer[i]) == -1) {
+			file->errnum = A8CAS_ERR_FWRITE;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int write_pwmd_block(A8CAS_FILE *file, unsigned int length_0, unsigned int length_1, uint8_t const *buffer, uint16_t length)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	unsigned int checksum = 0;
+
+	if (write_pwmd_block_bytes(file, length_0, length_1, buffer, length) != 0)
+		return 1;
+
+/* compute checksum */
+	checksum = 0;
+
+	if (fprintf(data->file, " ; length=%u, checksum=%u\n", (unsigned int)length, checksum) == -1) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+
+	return 0;
+}
+
 static int write_turbo2600_block(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const *buffer, uint16_t length)
 {
 	file_specific *data = (file_specific*) file->specific_data;
@@ -704,18 +756,18 @@ static int write_data_block(A8CAS_FILE *file, uint16_t irg_ms, uint8_t const *bu
 	return write_standard_block(file, irg_ms, buffer, length);
 }
 
-static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+static int write_various_signals_block(A8CAS_FILE *file, char *type, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
 {
 	file_specific *data = (file_specific*) file->specific_data;
 	unsigned long duration = 0;
 	unsigned int i;
 
-	if (fprintf(data->file, "fsk  %05"PRIu16, irg_ms) < 0) {
+	if (fprintf(data->file, "%s %05u", type, (unsigned int)irg_ms) < 0) {
 		file->errnum = A8CAS_ERR_FWRITE;
 		return 1;
 	}
 	for(i = 0; i < length; i ++) {
-		if (fprintf(data->file, " %"PRIu8, buffer[i]) < 0) {
+		if (fprintf(data->file, " %u", (unsigned int)buffer[i]) == -1) {
 			file->errnum = A8CAS_ERR_FWRITE;
 			return 1;
 		}
@@ -730,6 +782,44 @@ static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer,
 	return 0;
 }
 
+static int write_fsk_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+{
+	return write_various_signals_block(file, "fsk ", irg_ms, buffer, length);
+}
+
+static int write_pwmc_block(A8CAS_FILE *file, uint16_t irg_ms, pwmc_buffer *buffer, uint16_t length)
+{
+	file_specific *data = (file_specific*) file->specific_data;
+	unsigned int i;
+
+	if (fprintf(data->file, "pwmc %05u", (unsigned int)irg_ms) < 0) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+	for(i = 0; i < length; i ++) {
+		if (fprintf(data->file, " %u", (char)buffer[i].length) == -1) {
+			file->errnum = A8CAS_ERR_FWRITE;
+			return 1;
+		}
+		if (fprintf(data->file, " %u", (unsigned int)buffer[i].count) == -1) {
+			file->errnum = A8CAS_ERR_FWRITE;
+			return 1;
+		}
+	}
+
+	if (fprintf(data->file, " ; count=%u\n", (unsigned int)length) == -1) {
+		file->errnum = A8CAS_ERR_FWRITE;
+		return 1;
+	}
+
+	return 0;
+}
+
+static int write_pwml_block(A8CAS_FILE *file, uint16_t irg_ms, uint16_t *buffer, uint16_t length)
+{
+	return write_various_signals_block(file, "pwml", irg_ms, buffer, length);
+}
+
 /* ------------------------------------------------------------------------ *
  * Write functions                                                          *
  * ------------------------------------------------------------------------ */
@@ -1116,6 +1206,10 @@ int FORMAT_HEX_open(A8CAS_FILE *file, char const *path, A8CAS_info *info)
 	data->cas_encode.write_baud_block_func = &write_baud_block;
 	data->cas_encode.write_data_block_func = &write_data_block;
 	data->cas_encode.write_fsk_block_func = &write_fsk_block;
+	data->cas_encode.write_pwms_block_func = &write_pwms_block;
+	data->cas_encode.write_pwmd_block_func = &write_pwmd_block;
+	data->cas_encode.write_pwmc_block_func = &write_pwmc_block;
+	data->cas_encode.write_pwml_block_func = &write_pwml_block;
 	data->cas_encode.add_block_offset_func = &add_offset_after_write_block;
 
 	data->read_audio.mod_type = MOD_TYPE_FSK;
diff --git a/src/format_sndfile.c b/src/format_sndfile.c
index 3ed852b..b33fade 100644
--- a/src/format_sndfile.c
+++ b/src/format_sndfile.c
@@ -70,6 +70,7 @@ struct file_specific {
 		PWM_DEMOD_t pwm;
 	} demod;
 	int (*advance_demod_func)(file_specific*, short int);
+	int pwm_mod;
 
 /* Fields used while block counting and rewinding */
 	/* Number of samples already read / number of the next sample
@@ -233,7 +234,11 @@ static int specific_write(A8CAS_FILE *file, A8CAS_signal const *sig)
 	{
 		unsigned int free_space = DEFAULT_BUF_SIZE - data->buffer_write_fill;
 		if (samples_to_write >= free_space) { /* wrap */
-			FSK_MOD_generate(&data->mod.fsk, data->buffer + data->buffer_write_fill,
+			if (data->pwm_mod)
+				PWM_MOD_generate(&data->mod.pwm, data->buffer + data->buffer_write_fill,
+			                 free_space, sig->signal);
+			else
+				FSK_MOD_generate(&data->mod.fsk, data->buffer + data->buffer_write_fill,
 			                 free_space, sig->signal);
 			data->buffer_write_fill = DEFAULT_BUF_SIZE;
 			if ((file->errnum = flush_data(data)) != A8CAS_ERR_NONE)
@@ -241,7 +246,11 @@ static int specific_write(A8CAS_FILE *file, A8CAS_signal const *sig)
 			data->buffer_write_fill = 0;
 			samples_to_write -= free_space;
 		} else {
-			FSK_MOD_generate(&data->mod.fsk, data->buffer + data->buffer_write_fill,
+			if (data->pwm_mod)
+				PWM_MOD_generate(&data->mod.pwm, data->buffer + data->buffer_write_fill,
+			                 samples_to_write, sig->signal);
+			else
+				FSK_MOD_generate(&data->mod.fsk, data->buffer + data->buffer_write_fill,
 			                 samples_to_write, sig->signal);
 			data->buffer_write_fill += samples_to_write;
 			data->file_offset += (sf_count_t)sample_time;
@@ -365,7 +374,9 @@ void FORMAT_SNDFILE_set_audio(A8CAS_FILE *file)
 {
 	file_specific *data = (file_specific*) file->specific_data;
 
+	PWM_MOD_init(&data->audio_mod.pwm, file->audio.samplerate, file->audio.bits, 1, 0);
 	FSK_MOD_init(&data->audio_mod.fsk, file->audio.samplerate, file->audio.bits, 1, 0, A8CAS_MARK_FREQ, A8CAS_SPACE_FREQ);
+
 	RESAMPLE_init(&data->resample, data->snd_info.samplerate, file->audio.samplerate);
 }
 
@@ -428,13 +439,40 @@ int FORMAT_SNDFILE_read_audio(A8CAS_FILE *file, void *samples, unsigned int num_
 	return num_samples;
 }
 
+/* Deprecated */
 int FORMAT_SNDFILE_write_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples)
 {
+	unsigned int dummy_number;
+
+	return FORMAT_SNDFILE_write_with_audio(file, sig, samples, &dummy_number);
+}
+
+int FORMAT_SNDFILE_write_with_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples, unsigned int *audio_samples)
+{
 	file_specific *data = (file_specific*) file->specific_data;
+	short int sample;
 
 	if ((*file->write_func)(file, sig) != 0)
 		return 1;
-	FSK_MOD_generate(&data->audio_mod.fsk, samples, sig->length, sig->signal);
+
+	*audio_samples = 0;
+	for (int i=0; i < sig->length; i++) {
+		sample = (sig->signal == 1 ? USHRT_MAX : 0);
+		if (RESAMPLE_next(&data->resample, &sample)) {
+			(*audio_samples) ++;
+			while (!data->resample.need)
+				if (RESAMPLE_next(&data->resample, &sample))
+					(*audio_samples) ++;
+		}
+	}
+
+	if (*audio_samples > 0) {
+		if (data->pwm_mod) {
+			PWM_MOD_generate(&data->audio_mod.pwm, samples, *audio_samples, sig->signal);
+		}
+		else
+			FSK_MOD_generate(&data->audio_mod.fsk, samples, *audio_samples, sig->signal);
+	}
 	return 0;
 }
 
@@ -583,9 +621,11 @@ static void reset_before_read_bytes(A8CAS_FILE *file)
 static int common_read_bytes_after_write(A8CAS_FILE *file)
 {
 	if (reset_after_write(file) != 0)
+
 		return 1;
 	reset_before_read_bytes(file);
 	reset_buffer(file);
+
 	return 0;
 }
 
@@ -733,6 +773,9 @@ int FORMAT_SNDFILE_set_param(A8CAS_FILE *file, A8CAS_param type, void const *val
 	file_specific *data = (file_specific*) file->specific_data;
 
 	switch (type) {
+	case A8CAS_PARAM_PWM_ENCODE:
+		data->pwm_mod = *((int *) value);
+		break;
 	case A8CAS_PARAM_PWM_DECODE:
 		if (*((int *) value)) {
 			PWM_DEMOD_init(&data->demod.pwm);
@@ -778,6 +821,7 @@ int FORMAT_SNDFILE_set_param(A8CAS_FILE *file, A8CAS_param type, void const *val
 		data->demod.fsk.silence_threshold = *((float *)value);
 		break;
 	case A8CAS_PARAM_CROSSTALK_VOLUME:
+		PWM_MOD_set_volume(&data->audio_mod.pwm, *((float *)value));
 		FSK_MOD_set_volume(&data->audio_mod.fsk, *((float *)value));
 		data->crosstalk_volume = *((float *)value) * USHRT_MAX;
 		break;
@@ -793,6 +837,9 @@ int FORMAT_SNDFILE_get_param(A8CAS_FILE *file, A8CAS_param type, void *value)
 	file_specific *data = (file_specific*) file->specific_data;
 
 	switch (type) {
+	case A8CAS_PARAM_PWM_ENCODE:
+		*((int *) value) = data->pwm_mod;
+		break;
 	case A8CAS_PARAM_PWM_DECODE:
 		*((int *) value) = (data->advance_demod_func == &advance_pwm_demod);
 		break;
@@ -923,10 +970,15 @@ int FORMAT_SNDFILE_open(A8CAS_FILE *file, char const *path, A8CAS_info *info)
 	data->demod.pwm.tolerance = PWM_DEMOD_DEFAULT_TOLERANCE;
 	data->demod.fsk.silence_threshold = FSK_DEMOD_DEFAULT_SILENCE_THRESHOLD;
 
+	data->pwm_mod = 0;
+
 	data->crosstalk_volume = USHRT_MAX / 20;
 	FSK_MOD_init(&data->mod.fsk, data->snd_info.samplerate, 16,
 	             data->snd_info.channels, data->signal_channel_num,
 	             A8CAS_MARK_FREQ, A8CAS_SPACE_FREQ);
 
+	PWM_MOD_init(&data->mod.pwm, data->snd_info.samplerate, 16,
+	             data->snd_info.channels, data->signal_channel_num);
+
 	return 0;
 }
diff --git a/src/format_sndfile.h b/src/format_sndfile.h
index 5ebf959..df957f0 100644
--- a/src/format_sndfile.h
+++ b/src/format_sndfile.h
@@ -37,6 +37,7 @@ enum { FORMAT_SNDFILE_SEEK_UNIT = A8CAS_SEEK_UNIT_SAMPLES };
 void FORMAT_SNDFILE_set_audio(A8CAS_FILE *file);
 int FORMAT_SNDFILE_read_audio(A8CAS_FILE *file, void *samples, unsigned int num_samples);
 int FORMAT_SNDFILE_write_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples);
+int FORMAT_SNDFILE_write_with_audio(A8CAS_FILE *file, A8CAS_signal const *sig, void *samples, unsigned int *num_samples);
 
 unsigned int FORMAT_SNDFILE_read_bytes(A8CAS_FILE *file, unsigned char *bytes, unsigned int size, unsigned int *baudrate);
 unsigned int FORMAT_SNDFILE_read_signals(A8CAS_FILE *file, A8CAS_signal *sigs, unsigned int size);
diff --git a/src/pwm.h b/src/pwm.h
new file mode 100644
index 0000000..1178d81
--- /dev/null
+++ b/src/pwm.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2010 Tomasz Krasuski (see AUTHORS)
+ *
+ * This file is part of the A8CAS project which allows to manipulate tape
+ * images for Atari 8-bit computers.
+ *
+ * A8CAS is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * A8CAS is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with A8CAS; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
+ */
+
+#ifndef PWM_H
+#define PWM_H
+
+typedef struct pwmc_buffer {
+	uint8_t length;
+	uint16_t count;
+} pwmc_buffer;
+
+#endif /* PWM_H */
diff --git a/src/pwm_mod.c b/src/pwm_mod.c
index 7cab802..d9942b3 100644
--- a/src/pwm_mod.c
+++ b/src/pwm_mod.c
@@ -25,13 +25,21 @@
 
 static void generate_8bit(PWM_MOD_t *mod, void *buffer, unsigned int num_samples, int signal)
 {
+	static float const add = (float) UCHAR_MAX / 2.0f;
 	float volume = mod->volume;
 	unsigned int i, j;
 	unsigned char *buf = (unsigned char *)buffer;
+	static int same_level_len = 0;
+	static int last_signal=-1;
 
+	if (signal!=last_signal) same_level_len = 0;
 	for (i = 0, j = mod->write_channel; i < num_samples; i ++, j += mod->num_channels) {
-		buf[j] = (unsigned char)((signal ? 1.0f : 0.0f) * volume);
+		buf[j] = (unsigned char)( same_level_len < 2 * mod->samples_per_ms ? ((signal ? 1.0f : 0.0f) * volume + add) :
+				  same_level_len < 10 * mod->samples_per_ms ? ((signal ? 0.0f : 1.0f) * volume/1.5f + add) :
+				  same_level_len < 10.5f * mod->samples_per_ms ? ((signal ? 1.0f : 0.0f) * volume/2.0f + add) :
+				  same_level_len < 11 * mod->samples_per_ms ? ((signal ? 0.0f : 1.0f) * volume/4.0f) : add);
 	}
+	last_signal = signal;
 }
 
 static void generate_16bit(PWM_MOD_t *mod, void *buffer, unsigned int num_samples, int signal)
@@ -40,10 +48,19 @@ static void generate_16bit(PWM_MOD_t *mod, void *buffer, unsigned int num_sample
 	float volume = mod->volume;
 	unsigned int i, j;
 	short *buf = (short *)buffer;
+	static int same_level_len = 0;
+	static int last_signal=-1;
 
+	if (signal!=last_signal) same_level_len = 0;
 	for (i = 0, j = mod->write_channel; i < num_samples; i ++, j += mod->num_channels) {
-		buf[j] = (short)((signal ? 1.0f : -1.0f) * volume + add);
+		/* make data tails pretty ;) and functional */
+		same_level_len++;
+		buf[j] = (short)( same_level_len < 2 * mod->samples_per_ms ? ((signal ? 1.0f : -1.0f) * volume + add) :
+				  same_level_len < 10 * mod->samples_per_ms ? ((signal ? -1.0f : 1.0f) * volume/1.5f + add) :
+				  same_level_len < 10.5f * mod->samples_per_ms ? ((signal ? 1.0f : -1.0f) * volume/2.0f + add) :
+				  same_level_len < 11 * mod->samples_per_ms ? ((signal ? -1.0f : 1.0f) * volume/4.0f + add) : add);
 	}
+	last_signal = signal;
 }
 
 void PWM_MOD_init(PWM_MOD_t *mod, unsigned int samplerate, unsigned int bits, unsigned int num_channels, unsigned int write_channel)
@@ -54,6 +71,7 @@ void PWM_MOD_init(PWM_MOD_t *mod, unsigned int samplerate, unsigned int bits, un
 		mod->gen_func = &generate_8bit;
 	mod->num_channels = num_channels;
 	mod->write_channel = write_channel;
+	mod->samples_per_ms = (unsigned int) samplerate/1000;
 	PWM_MOD_set_volume(mod, 1.0f);
 }
 
diff --git a/src/pwm_mod.h b/src/pwm_mod.h
index cafa2a5..c9de579 100644
--- a/src/pwm_mod.h
+++ b/src/pwm_mod.h
@@ -29,6 +29,7 @@ struct PWM_MOD_t {
 	unsigned int num_channels;
 	unsigned int write_channel;
 	float volume;
+	unsigned int samples_per_ms;
 };
 
 void PWM_MOD_init(PWM_MOD_t *mod, unsigned int samplerate, unsigned int bits, unsigned int num_channels, unsigned int write_channel);