Index: uspace/lib/drv/generic/remote_audio_pcm_buffer.c
===================================================================
--- uspace/lib/drv/generic/remote_audio_pcm_buffer.c	(revision 6be06d048fcd0437feda2498ba4630c9e704ced2)
+++ uspace/lib/drv/generic/remote_audio_pcm_buffer.c	(revision 0336354af6a0ef42bed4e92ac4e266e50b954fee)
@@ -140,9 +140,12 @@
 
 int audio_pcm_buffer_start_record(async_exch_t *exch, unsigned id,
-    unsigned sample_rate, unsigned sample_size, unsigned channels, bool sign)
-{
-	if (!exch || sample_size > UINT16_MAX || channels > (UINT16_MAX >> 1))
-		return EINVAL;
-	sysarg_t packed = sample_size << 16 | channels << 1 | sign ? 1 : 0;
+    unsigned parts, unsigned sample_rate, uint16_t sample_size,
+    uint8_t channels, bool sign)
+{
+	if (!exch)
+		return EINVAL;
+	sysarg_t packed =
+	    (sample_size << 16) | (channels << 8) |
+	    ((parts & 0x7f) << 1) | (sign ? 1 : 0);
 	return async_req_4_0(exch, DEV_IFACE_ID(AUDIO_PCM_BUFFER_IFACE),
 	    IPC_M_AUDIO_PCM_START_RECORD, id, sample_rate, packed);
@@ -336,9 +339,10 @@
 	const unsigned rate = DEV_IPC_GET_ARG2(*call);
 	const unsigned size = DEV_IPC_GET_ARG3(*call) >> 16;
-	const unsigned channels = (DEV_IPC_GET_ARG3(*call) & UINT16_MAX) >> 1;
+	const unsigned channels = (DEV_IPC_GET_ARG3(*call) >> 8) & UINT8_MAX;
+	const unsigned parts = (DEV_IPC_GET_ARG3(*call) >> 1) & 0x7f;
 	const bool sign = (bool)(DEV_IPC_GET_ARG3(*call) & 1);
 
 	const int ret = pcm_iface->start_record
-	    ? pcm_iface->start_record(fun, id, rate, size, channels, sign)
+	    ? pcm_iface->start_record(fun, id, parts, rate, size, channels, sign)
 	    : ENOTSUP;
 	async_answer_0(callid, ret);
Index: uspace/lib/drv/include/audio_pcm_buffer_iface.h
===================================================================
--- uspace/lib/drv/include/audio_pcm_buffer_iface.h	(revision 6be06d048fcd0437feda2498ba4630c9e704ced2)
+++ uspace/lib/drv/include/audio_pcm_buffer_iface.h	(revision 0336354af6a0ef42bed4e92ac4e266e50b954fee)
@@ -51,6 +51,6 @@
 int audio_pcm_buffer_stop_playback(async_exch_t *, unsigned);
 
-int audio_pcm_buffer_start_record(async_exch_t *, unsigned,
-    unsigned, unsigned, unsigned, bool);
+int audio_pcm_buffer_start_record(async_exch_t *, unsigned, unsigned,
+    unsigned, uint16_t, uint8_t, bool);
 int audio_pcm_buffer_stop_record(async_exch_t *, unsigned);
 
@@ -64,5 +64,5 @@
 	    unsigned, unsigned, unsigned, bool);
 	int (*stop_playback)(ddf_fun_t *, unsigned);
-	int (*start_record)(ddf_fun_t *, unsigned,
+	int (*start_record)(ddf_fun_t *, unsigned, unsigned,
 	    unsigned, unsigned, unsigned, bool);
 	int (*stop_record)(ddf_fun_t *, unsigned);