diff --git a/src/input/binary.c b/src/input/binary.c
index 9ad988e3..15dc0da1 100644
--- a/src/input/binary.c
+++ b/src/input/binary.c
@@ -64,7 +64,7 @@ static int init(struct sr_input *in, GHashTable *options)
 	return SR_OK;
 }
 
-static int receive(const struct sr_input *in, GString *buf)
+static int receive(struct sr_input *in, GString *buf)
 {
 	struct sr_datafeed_packet packet;
 	struct sr_datafeed_meta meta;
@@ -80,16 +80,25 @@ static int receive(const struct sr_input *in, GString *buf)
 
 	num_channels = g_slist_length(in->sdi->channels);
 
+	if (!in->sdi_ready) {
+		/* sdi is ready, notify frontend. */
+		in->sdi_ready = TRUE;
+		return SR_OK;
+	}
+
 	if (!inc->started) {
 		std_session_send_df_header(in->sdi, LOG_PREFIX);
-		inc->started = TRUE;
 
-		packet.type = SR_DF_META;
-		packet.payload = &meta;
-		src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
-		meta.config = g_slist_append(NULL, src);
-		sr_session_send(in->sdi, &packet);
-		sr_config_free(src);
+		if (inc->samplerate) {
+			packet.type = SR_DF_META;
+			packet.payload = &meta;
+			src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
+			meta.config = g_slist_append(NULL, src);
+			sr_session_send(in->sdi, &packet);
+			sr_config_free(src);
+		}
+
+		inc->started = TRUE;
 	}
 
 	packet.type = SR_DF_LOGIC;
@@ -113,10 +122,12 @@ static int receive(const struct sr_input *in, GString *buf)
 
 static int cleanup(struct sr_input *in)
 {
-	struct sr_datafeed_packet packet;
 	struct context *inc;
+	struct sr_datafeed_packet packet;
 
 	inc = in->priv;
+	if (!inc)
+		return SR_OK;
 
 	if (inc->started) {
 		packet.type = SR_DF_END;
diff --git a/src/input/chronovu_la8.c b/src/input/chronovu_la8.c
index 42700dd1..9c82506a 100644
--- a/src/input/chronovu_la8.c
+++ b/src/input/chronovu_la8.c
@@ -76,7 +76,7 @@ static int init(struct sr_input *in, GHashTable *options)
 	return SR_OK;
 }
 
-static int receive(const struct sr_input *in, GString *buf)
+static int receive(struct sr_input *in, GString *buf)
 {
 	struct sr_datafeed_packet packet;
 	struct sr_datafeed_meta meta;
@@ -92,16 +92,25 @@ static int receive(const struct sr_input *in, GString *buf)
 
 	num_channels = g_slist_length(in->sdi->channels);
 
+	if (!in->sdi_ready) {
+		/* sdi is ready, notify frontend. */
+		in->sdi_ready = TRUE;
+		return SR_OK;
+	}
+
 	if (!inc->started) {
 		std_session_send_df_header(in->sdi, LOG_PREFIX);
-		inc->started = TRUE;
 
-		packet.type = SR_DF_META;
-		packet.payload = &meta;
-		src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
-		meta.config = g_slist_append(NULL, src);
-		sr_session_send(in->sdi, &packet);
-		sr_config_free(src);
+		if (inc->samplerate) {
+			packet.type = SR_DF_META;
+			packet.payload = &meta;
+			src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
+			meta.config = g_slist_append(NULL, src);
+			sr_session_send(in->sdi, &packet);
+			sr_config_free(src);
+		}
+
+		inc->started = TRUE;
 	}
 
 	packet.type = SR_DF_LOGIC;
@@ -125,10 +134,12 @@ static int receive(const struct sr_input *in, GString *buf)
 
 static int cleanup(struct sr_input *in)
 {
-	struct sr_datafeed_packet packet;
 	struct context *inc;
+	struct sr_datafeed_packet packet;
 
 	inc = in->priv;
+	if (!inc)
+		return SR_OK;
 
 	if (inc->started) {
 		packet.type = SR_DF_END;
diff --git a/src/input/csv.c b/src/input/csv.c
index c2625aa2..c6aabd96 100644
--- a/src/input/csv.c
+++ b/src/input/csv.c
@@ -589,11 +589,11 @@ static int initial_receive(const struct sr_input *in)
 
 	if (!(termination = get_line_termination(in->buf)))
 		/* Don't have a full line yet. */
-		return SR_OK_CONTINUE;
+		return SR_ERR_NA;
 
 	if (!(p = g_strrstr_len(in->buf->str, in->buf->len, termination)))
 		/* Don't have a full line yet. */
-		return SR_OK_CONTINUE;
+		return SR_ERR_NA;
 	len = p - in->buf->str - 1;
 	new_buf = g_string_new_len(in->buf->str, len);
 	g_string_append_c(new_buf, '\0');
@@ -610,7 +610,7 @@ static int initial_receive(const struct sr_input *in)
 	return ret;
 }
 
-static int receive(const struct sr_input *in, GString *buf)
+static int receive(struct sr_input *in, GString *buf)
 {
 	struct sr_datafeed_packet packet;
 	struct sr_datafeed_meta meta;
@@ -625,14 +625,18 @@ static int receive(const struct sr_input *in, GString *buf)
 
 	inc = in->priv;
 	if (!inc->termination) {
-		ret = initial_receive(in);
-		if (ret == SR_OK_CONTINUE)
+		if ((ret = initial_receive(in)) == SR_ERR_NA)
 			/* Not enough data yet. */
-			return SR_OK_CONTINUE;
+			return SR_OK;
 		else if (ret != SR_OK)
 			return SR_ERR;
 
-		inc->started = TRUE;
+		/* sdi is ready, notify frontend. */
+		in->sdi_ready = TRUE;
+		return SR_OK;
+	}
+
+	if (!inc->started) {
 		std_session_send_df_header(in->sdi, LOG_PREFIX);
 
 		if (inc->samplerate) {
@@ -644,6 +648,8 @@ static int receive(const struct sr_input *in, GString *buf)
 			sr_session_send(in->sdi, &packet);
 			sr_config_free(src);
 		}
+
+		inc->started = TRUE;
 	}
 
 	if (!(p = g_strrstr_len(in->buf->str, in->buf->len, inc->termination)))
diff --git a/src/input/input.c b/src/input/input.c
index 6bea92b5..02f7db1b 100644
--- a/src/input/input.c
+++ b/src/input/input.c
@@ -495,11 +495,18 @@ SR_API int sr_input_scan_file(const char *filename, const struct sr_input **in)
  * Return the input instance's (virtual) device instance. This can be
  * used to find out the number of channels and other information.
  *
+ * If the device instance has not yet been fully populated by the input
+ * module, NULL is returned. This indicates the module needs more data
+ * to identify the number of channels and so on.
+ *
  * @since 0.4.0
  */
 SR_API struct sr_dev_inst *sr_input_dev_inst_get(const struct sr_input *in)
 {
-	return in->sdi;
+	if (in->sdi_ready)
+		return in->sdi;
+	else
+		return NULL;
 }
 
 /**
@@ -508,12 +515,18 @@ SR_API struct sr_dev_inst *sr_input_dev_inst_get(const struct sr_input *in)
  * When an input module instance is created with sr_input_new(), this
  * function is used to feed data to the instance.
  *
+ * As enough data gets fed into this function to completely populate
+ * the device instance associated with this input instance, this is
+ * guaranteed to return the moment it's ready. This gives the caller
+ * the chance to examine the device instance, attach session callbacks
+ * and on so.
+ *
  * @since 0.4.0
  */
 SR_API int sr_input_send(const struct sr_input *in, GString *buf)
 {
 	sr_spew("Sending %d bytes to %s module.", buf->len, in->module->id);
-	return in->module->receive(in, buf);
+	return in->module->receive((struct sr_input *)in, buf);
 }
 
 /**
@@ -533,6 +546,10 @@ SR_API int sr_input_free(const struct sr_input *in)
 		ret = in->module->cleanup((struct sr_input *)in);
 	if (in->sdi)
 		sr_dev_inst_free(in->sdi);
+	if (in->buf->len > 64) {
+		/* That seems more than just some sub-unitsize leftover... */
+		sr_warn("Found %d unprocessed bytes at free time.", in->buf->len);
+	}
 	if (in->buf)
 		g_string_free(in->buf, TRUE);
 	g_free((gpointer)in);
diff --git a/src/input/vcd.c b/src/input/vcd.c
index d50374ab..9d164f98 100644
--- a/src/input/vcd.c
+++ b/src/input/vcd.c
@@ -409,8 +409,6 @@ static int init(struct sr_input *in, GHashTable *options)
 	char name[16];
 	struct context *inc;
 
-	inc = g_malloc0(sizeof(struct context));
-
 	num_channels = g_variant_get_int32(g_hash_table_lookup(options, "numchannels"));
 	if (num_channels < 1) {
 		sr_err("Invalid value for numchannels: must be at least 1.");
@@ -420,6 +418,7 @@ static int init(struct sr_input *in, GHashTable *options)
 		sr_err("No more than 64 channels supported.");
 		return SR_ERR_ARG;
 	}
+	inc = in->priv = g_malloc0(sizeof(struct context));
 	inc->maxchannels = num_channels;
 
 	inc->downsample = g_variant_get_int32(g_hash_table_lookup(options, "downsample"));
@@ -458,7 +457,7 @@ static gboolean have_header(GString *buf)
 	return FALSE;
 }
 
-static int receive(const struct sr_input *in, GString *buf)
+static int receive(struct sr_input *in, GString *buf)
 {
 	struct sr_datafeed_packet packet;
 	struct sr_datafeed_meta meta;
@@ -477,8 +476,13 @@ static int receive(const struct sr_input *in, GString *buf)
 			/* There was a header in there, but it was malformed. */
 			return SR_ERR;
 
+		in->sdi_ready = TRUE;
+		/* sdi is ready, notify frontend. */
+		return SR_OK;
+	}
+
+	if (!inc->started) {
 		std_session_send_df_header(in->sdi, LOG_PREFIX);
-		inc->started = TRUE;
 
 		packet.type = SR_DF_META;
 		packet.payload = &meta;
@@ -487,6 +491,8 @@ static int receive(const struct sr_input *in, GString *buf)
 		meta.config = g_slist_append(NULL, src);
 		sr_session_send(in->sdi, &packet);
 		sr_config_free(src);
+
+		inc->started = TRUE;
 	}
 
 	while ((p = g_strrstr_len(in->buf->str, in->buf->len, "\n"))) {
diff --git a/src/input/wav.c b/src/input/wav.c
index 52820956..b6a7e518 100644
--- a/src/input/wav.c
+++ b/src/input/wav.c
@@ -43,6 +43,7 @@
 #define WAVE_FORMAT_EXTENSIBLE   0xfffe
 
 struct context {
+	gboolean started;
 	int fmt_code;
 	uint64_t samplerate;
 	int samplesize;
@@ -57,7 +58,7 @@ static int parse_wav_header(GString *buf, struct context *inc)
 	unsigned int fmt_code, samplesize, num_channels, unitsize;
 
 	if (buf->len < MIN_DATA_CHUNK_OFFSET)
-		return SR_OK_CONTINUE;
+		return SR_ERR_NA;
 
 	fmt_code = RL16(buf->str + 20);
 	samplerate = RL32(buf->str + 24);
@@ -82,7 +83,7 @@ static int parse_wav_header(GString *buf, struct context *inc)
 	} else if (fmt_code == WAVE_FORMAT_EXTENSIBLE) {
 		if (buf->len < 70)
 			/* Not enough for extensible header and next chunk. */
-			return SR_OK_CONTINUE;
+			return SR_ERR_NA;
 
 		if (RL16(buf->str + 16) != 40) {
 			sr_err("WAV extensible format chunk must be 40 bytes.");
@@ -150,6 +151,7 @@ static int init(struct sr_input *in, GHashTable *options)
 	(void)options;
 
 	in->sdi = sr_dev_inst_new(SR_ST_ACTIVE, NULL, NULL, NULL);
+	in->priv = g_malloc0(sizeof(struct context));
 
 	return SR_OK;
 }
@@ -177,42 +179,6 @@ static int find_data_chunk(GString *buf, int initial_offset)
 	return offset;
 }
 
-static int initial_receive(struct sr_input *in)
-{
-	struct sr_datafeed_packet packet;
-	struct sr_datafeed_meta meta;
-	struct sr_channel *ch;
-	struct sr_config *src;
-	struct context *inc;
-	int ret, i;
-	char channelname[8];
-
-	if (!in->buf)
-		/* Shouldn't happen. */
-		return SR_ERR;
-
-	inc = in->priv = g_malloc(sizeof(struct context));
-	if ((ret = parse_wav_header(in->buf, inc)) != SR_OK)
-		return ret;
-
-	for (i = 0; i < inc->num_channels; i++) {
-		snprintf(channelname, 8, "CH%d", i + 1);
-		ch = sr_channel_new(i, SR_CHANNEL_ANALOG, TRUE, channelname);
-		in->sdi->channels = g_slist_append(in->sdi->channels, ch);
-	}
-
-	std_session_send_df_header(in->sdi, LOG_PREFIX);
-
-	packet.type = SR_DF_META;
-	packet.payload = &meta;
-	src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
-	meta.config = g_slist_append(NULL, src);
-	sr_session_send(in->sdi, &packet);
-	sr_config_free(src);
-
-	return SR_OK;
-}
-
 static void send_chunk(const struct sr_input *in, int offset, int num_samples)
 {
 	struct sr_datafeed_packet packet;
@@ -269,25 +235,58 @@ static void send_chunk(const struct sr_input *in, int offset, int num_samples)
 	sr_session_send(in->sdi, &packet);
 }
 
-static int receive(const struct sr_input *in, GString *buf)
+static int receive(struct sr_input *in, GString *buf)
 {
+	struct sr_datafeed_packet packet;
+	struct sr_datafeed_meta meta;
+	struct sr_channel *ch;
+	struct sr_config *src;
 	struct context *inc;
-	int offset, chunk_samples, total_samples, processed, max_chunk_samples, num_samples, i;
+	int offset, chunk_samples, total_samples, processed, max_chunk_samples;
+	int num_samples, ret, i;
+	char channelname[8];
 
 	g_string_append_len(in->buf, buf->str, buf->len);
 
-	if (!in->priv) {
-		if (initial_receive((struct sr_input *)in) != SR_OK)
-			return SR_ERR;
-		if (in->buf->len < MIN_DATA_CHUNK_OFFSET) {
-			/*
-			 * Don't even get started until there's enough room
-			 * for the data segment to start.
-			 */
-			return SR_OK;
-		}
+	if (in->buf->len < MIN_DATA_CHUNK_OFFSET) {
+		/*
+		 * Don't even try until there's enough room
+		 * for the data segment to start.
+		 */
+		return SR_OK;
 	}
+
 	inc = in->priv;
+	if (!in->sdi_ready) {
+		if ((ret = parse_wav_header(in->buf, inc)) == SR_ERR_NA)
+			/* Not enough data yet. */
+			return SR_OK;
+		else if (ret != SR_OK)
+			return ret;
+
+		/* sdi is ready, notify frontend. */
+		in->sdi_ready = TRUE;
+		return SR_OK;
+	}
+
+	if (!inc->started) {
+		for (i = 0; i < inc->num_channels; i++) {
+			snprintf(channelname, 8, "CH%d", i + 1);
+			ch = sr_channel_new(i, SR_CHANNEL_ANALOG, TRUE, channelname);
+			in->sdi->channels = g_slist_append(in->sdi->channels, ch);
+		}
+
+		std_session_send_df_header(in->sdi, LOG_PREFIX);
+
+		packet.type = SR_DF_META;
+		packet.payload = &meta;
+		src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(inc->samplerate));
+		meta.config = g_slist_append(NULL, src);
+		sr_session_send(in->sdi, &packet);
+		sr_config_free(src);
+
+		inc->started = TRUE;
+	}
 
 	if (!inc->found_data) {
 		/* Skip past size of 'fmt ' chunk. */
@@ -334,15 +333,16 @@ static int receive(const struct sr_input *in, GString *buf)
 static int cleanup(struct sr_input *in)
 {
 	struct sr_datafeed_packet packet;
+	struct context *inc;
 
-	if (in->priv) {
+	inc = in->priv;
+	if (inc->started) {
 		/* End of stream. */
 		packet.type = SR_DF_END;
 		sr_session_send(in->sdi, &packet);
-
-		g_free(in->priv);
-		in->priv = NULL;
 	}
+	g_free(in->priv);
+	in->priv = NULL;
 
 	return SR_OK;
 }
diff --git a/src/libsigrok-internal.h b/src/libsigrok-internal.h
index 67c0aab6..d1819985 100644
--- a/src/libsigrok-internal.h
+++ b/src/libsigrok-internal.h
@@ -211,6 +211,7 @@ struct sr_input {
 	const struct sr_input_module *module;
 	GString *buf;
 	struct sr_dev_inst *sdi;
+	gboolean sdi_ready;
 	void *priv;
 };
 
@@ -306,7 +307,7 @@ struct sr_input_module {
 	 * @retval SR_OK Success
 	 * @retval other Negative error code.
 	 */
-	int (*receive) (const struct sr_input *in, GString *buf);
+	int (*receive) (struct sr_input *in, GString *buf);
 
 	/**
 	 * This function is called after the caller is finished using