diff --git a/pinos/client/stream.c b/pinos/client/stream.c
index 1476aa67e..91045fc25 100644
--- a/pinos/client/stream.c
+++ b/pinos/client/stream.c
@@ -192,6 +192,7 @@ pinos_stream_new (PinosContext    *context,
   pinos_signal_init (&this->add_buffer);
   pinos_signal_init (&this->remove_buffer);
   pinos_signal_init (&this->new_buffer);
+  pinos_signal_init (&this->need_buffer);
 
   this->state = PINOS_STREAM_STATE_UNCONNECTED;
 
@@ -473,6 +474,9 @@ on_rtsocket_condition (SpaSource    *source,
         handle_rtnode_event (stream, ev);
       }
     }
+    if (cmd & PINOS_TRANSPORT_CMD_NEED_DATA) {
+      pinos_signal_emit (&stream->need_buffer, stream);
+    }
   }
 }
 
@@ -1080,16 +1084,15 @@ pinos_stream_send_buffer (PinosStream     *stream,
 {
   PinosStreamImpl *impl = SPA_CONTAINER_OF (stream, PinosStreamImpl, this);
   BufferId *bid;
+  uint8_t cmd = PINOS_TRANSPORT_CMD_HAVE_DATA;
 
   if ((bid = find_buffer (stream, id))) {
-    uint8_t cmd = PINOS_TRANSPORT_CMD_HAVE_DATA;
-
     bid->used = true;
     impl->trans->outputs[0].buffer_id = id;
     impl->trans->outputs[0].status = SPA_RESULT_OK;
-    write (impl->rtfd, &cmd, 1);
-    return true;
-  } else {
-    return true;
+    if (write (impl->rtfd, &cmd, 1) < 1)
+      perror ("write");
   }
+
+  return true;
 }
diff --git a/pinos/client/stream.h b/pinos/client/stream.h
index caac7c0fd..22a319251 100644
--- a/pinos/client/stream.h
+++ b/pinos/client/stream.h
@@ -91,6 +91,8 @@ struct _PinosStream {
   PINOS_SIGNAL (new_buffer,    (PinosListener *listener,
                                 PinosStream   *stream,
                                 uint32_t       id));
+  PINOS_SIGNAL (need_buffer,   (PinosListener *listener,
+                                PinosStream   *stream));
 };
 
 PinosStream *    pinos_stream_new               (PinosContext    *context,
diff --git a/pinos/gst/gstpinospool.c b/pinos/gst/gstpinospool.c
index 889efa2c9..7138a9a8c 100644
--- a/pinos/gst/gstpinospool.c
+++ b/pinos/gst/gstpinospool.c
@@ -75,6 +75,7 @@ acquire_buffer (GstBufferPool * pool, GstBuffer ** buffer,
 
   GST_OBJECT_LOCK (pool);
   while (p->available.length == 0) {
+    GST_WARNING ("queue empty");
     g_cond_wait (&p->cond, GST_OBJECT_GET_LOCK (pool));
   }
   *buffer = g_queue_pop_head (&p->available);
diff --git a/pinos/gst/gstpinossink.c b/pinos/gst/gstpinossink.c
index c858ef813..86cd2c81d 100644
--- a/pinos/gst/gstpinossink.c
+++ b/pinos/gst/gstpinossink.c
@@ -230,6 +230,8 @@ gst_pinos_sink_init (GstPinosSink * sink)
   sink->buf_ids = g_hash_table_new_full (g_direct_hash, g_direct_equal, NULL,
       (GDestroyNotify) gst_buffer_unref);
 
+  g_queue_init (&sink->queue);
+
   sink->loop = pinos_loop_new ();
   sink->main_loop = pinos_thread_main_loop_new (sink->loop, "pinos-sink-loop");
   GST_DEBUG ("loop %p %p", sink->loop, sink->main_loop);
@@ -347,6 +349,7 @@ typedef struct {
   SpaBuffer *buf;
   SpaMetaHeader *header;
   guint flags;
+  goffset offset;
 } ProcessMemData;
 
 static void
@@ -403,13 +406,15 @@ on_add_buffer (PinosListener *listener,
       case SPA_DATA_TYPE_DMABUF:
       {
         gmem = gst_fd_allocator_alloc (pinossink->allocator, dup (d->fd),
-                  d->size, GST_FD_MEMORY_FLAG_NONE);
-        gst_memory_resize (gmem, d->chunk->offset, d->chunk->size);
+                  d->mapoffset + d->maxsize, GST_FD_MEMORY_FLAG_NONE);
+        gst_memory_resize (gmem, d->chunk->offset + d->mapoffset, d->chunk->size);
+        data.offset = d->mapoffset;
         break;
       }
       case SPA_DATA_TYPE_MEMPTR:
-        gmem = gst_memory_new_wrapped (0, d->data, d->size, d->chunk->offset,
+        gmem = gst_memory_new_wrapped (0, d->data, d->maxsize, d->chunk->offset,
                                        d->chunk->size, NULL, NULL);
+        data.offset = 0;
         break;
       default:
         break;
@@ -466,6 +471,51 @@ on_new_buffer (PinosListener *listener,
   }
 }
 
+static void
+do_send_buffer (GstPinosSink *pinossink)
+{
+  GstBuffer *buffer;
+  ProcessMemData *data;
+  gboolean res;
+  guint i;
+
+  buffer = g_queue_pop_head (&pinossink->queue);
+  if (buffer == NULL)
+    return;
+
+  data = gst_mini_object_get_qdata (GST_MINI_OBJECT_CAST (buffer),
+                                    process_mem_data_quark);
+
+  if (data->header) {
+    data->header->seq = GST_BUFFER_OFFSET (buffer);
+    data->header->pts = GST_BUFFER_PTS (buffer);
+    data->header->dts_offset = GST_BUFFER_DTS (buffer);
+  }
+  for (i = 0; i < data->buf->n_datas; i++) {
+    SpaData *d = &data->buf->datas[i];
+    GstMemory *mem = gst_buffer_peek_memory (buffer, i);
+    d->chunk->offset = mem->offset - data->offset;
+    d->chunk->size = mem->size;
+  }
+
+  if (!(res = pinos_stream_send_buffer (pinossink->stream, data->id)))
+    g_warning ("can't send buffer");
+
+  pinossink->need_ready--;
+}
+
+
+static void
+on_need_buffer (PinosListener *listener,
+                PinosStream   *stream)
+{
+  GstPinosSink *pinossink = SPA_CONTAINER_OF (listener, GstPinosSink, stream_need_buffer);
+
+  pinossink->need_ready++;
+  GST_DEBUG ("need buffer %u", pinossink->need_ready);
+  do_send_buffer (pinossink);
+}
+
 static void
 on_state_changed (PinosListener *listener,
                   PinosStream   *stream)
@@ -610,9 +660,6 @@ static GstFlowReturn
 gst_pinos_sink_render (GstBaseSink * bsink, GstBuffer * buffer)
 {
   GstPinosSink *pinossink;
-  gboolean res;
-  ProcessMemData *data;
-  guint i;
 
   pinossink = GST_PINOS_SINK (bsink);
 
@@ -633,25 +680,11 @@ gst_pinos_sink_render (GstBaseSink * bsink, GstBuffer * buffer)
     buffer = b;
   }
 
-  data = gst_mini_object_get_qdata (GST_MINI_OBJECT_CAST (buffer),
-                                    process_mem_data_quark);
-
-  if (data->header) {
-    data->header->seq = GST_BUFFER_OFFSET (buffer);
-    data->header->pts = GST_BUFFER_PTS (buffer);
-    data->header->dts_offset = GST_BUFFER_DTS (buffer);
-  }
-  for (i = 0; i < data->buf->n_datas; i++) {
-    SpaData *d = &data->buf->datas[i];
-    GstMemory *mem = gst_buffer_peek_memory (buffer, i);
-    d->chunk->offset = mem->offset;
-    d->chunk->size = mem->size;
-  }
   gst_buffer_ref (buffer);
+  g_queue_push_tail (&pinossink->queue, buffer);
 
-  if (!(res = pinos_stream_send_buffer (pinossink->stream, data->id)))
-    g_warning ("can't send buffer");
-
+  if (pinossink->need_ready)
+    do_send_buffer (pinossink);
 
 done:
   pinos_thread_main_loop_unlock (pinossink->main_loop);
@@ -707,6 +740,7 @@ gst_pinos_sink_start (GstBaseSink * basesink)
   pinos_signal_add (&pinossink->stream->add_buffer, &pinossink->stream_add_buffer, on_add_buffer);
   pinos_signal_add (&pinossink->stream->remove_buffer, &pinossink->stream_remove_buffer, on_remove_buffer);
   pinos_signal_add (&pinossink->stream->new_buffer, &pinossink->stream_new_buffer, on_new_buffer);
+  pinos_signal_add (&pinossink->stream->need_buffer, &pinossink->stream_need_buffer, on_need_buffer);
   pinos_thread_main_loop_unlock (pinossink->main_loop);
 
   return TRUE;
diff --git a/pinos/gst/gstpinossink.h b/pinos/gst/gstpinossink.h
index 9e413ee00..abb442ffa 100644
--- a/pinos/gst/gstpinossink.h
+++ b/pinos/gst/gstpinossink.h
@@ -89,6 +89,7 @@ struct _GstPinosSink {
   PinosListener stream_add_buffer;
   PinosListener stream_remove_buffer;
   PinosListener stream_new_buffer;
+  PinosListener stream_need_buffer;
 
   GstAllocator *allocator;
   GstStructure *properties;
@@ -96,6 +97,8 @@ struct _GstPinosSink {
 
   GstPinosPool *pool;
   GHashTable *buf_ids;
+  GQueue queue;
+  guint need_ready;
 };
 
 struct _GstPinosSinkClass {
diff --git a/pinos/gst/gstpinossrc.c b/pinos/gst/gstpinossrc.c
index 635a8d665..ccb4e9bc9 100644
--- a/pinos/gst/gstpinossrc.c
+++ b/pinos/gst/gstpinossrc.c
@@ -173,13 +173,19 @@ clock_disabled:
   }
 }
 
+static void
+clear_queue (GstPinosSrc *pinossrc)
+{
+  g_queue_foreach (&pinossrc->queue, (GFunc) gst_mini_object_unref, NULL);
+  g_queue_clear (&pinossrc->queue);
+}
+
 static void
 gst_pinos_src_finalize (GObject * object)
 {
   GstPinosSrc *pinossrc = GST_PINOS_SRC (object);
 
-  g_queue_foreach (&pinossrc->queue, (GFunc) gst_mini_object_unref, NULL);
-  g_queue_clear (&pinossrc->queue);
+  clear_queue (pinossrc);
 
   pinos_thread_main_loop_destroy (pinossrc->main_loop);
   pinossrc->main_loop = NULL;
@@ -340,6 +346,7 @@ typedef struct {
   SpaBuffer *buf;
   SpaMetaHeader *header;
   guint flags;
+  goffset offset;
 } ProcessMemData;
 
 static void
@@ -417,13 +424,15 @@ on_add_buffer (PinosListener *listener,
       case SPA_DATA_TYPE_DMABUF:
       {
         gmem = gst_fd_allocator_alloc (pinossrc->fd_allocator, dup (d->fd),
-                  d->size, GST_FD_MEMORY_FLAG_NONE);
-        gst_memory_resize (gmem, d->chunk->offset, d->chunk->size);
+                  d->maxsize, GST_FD_MEMORY_FLAG_NONE);
+        gst_memory_resize (gmem, d->chunk->offset + d->mapoffset, d->chunk->size);
+        data.offset = d->mapoffset;
         break;
       }
       case SPA_DATA_TYPE_MEMPTR:
-        gmem = gst_memory_new_wrapped (0, d->data, d->size, d->chunk->offset,
+        gmem = gst_memory_new_wrapped (0, d->data, d->maxsize, d->chunk->offset + d->mapoffset,
                   d->chunk->size, NULL, NULL);
+        data.offset = 0;
       default:
         break;
     }
@@ -488,7 +497,7 @@ on_new_buffer (PinosListener *listener,
   for (i = 0; i < data->buf->n_datas; i++) {
     SpaData *d = &data->buf->datas[i];
     GstMemory *mem = gst_buffer_peek_memory (buf, i);
-    mem->offset = d->chunk->offset;
+    mem->offset = d->chunk->offset + data->offset;
     mem->size = d->chunk->size;
   }
   g_queue_push_tail (&pinossrc->queue, buf);
@@ -937,13 +946,6 @@ gst_pinos_src_start (GstBaseSrc * basesrc)
   return TRUE;
 }
 
-static void
-clear_queue (GstPinosSrc *pinossrc)
-{
-  g_queue_foreach (&pinossrc->queue, (GFunc) gst_mini_object_unref, NULL);
-  g_queue_clear (&pinossrc->queue);
-}
-
 static gboolean
 gst_pinos_src_stop (GstBaseSrc * basesrc)
 {
diff --git a/pinos/server/client-node.c b/pinos/server/client-node.c
index 3dd0ccae5..2a1147b35 100644
--- a/pinos/server/client-node.c
+++ b/pinos/server/client-node.c
@@ -195,6 +195,11 @@ spa_proxy_node_send_command (SpaNode        *node,
                                    PINOS_MESSAGE_NODE_COMMAND,
                                    &cnc,
                                    true);
+      if (command->type == SPA_NODE_COMMAND_START) {
+        uint8_t cmd = PINOS_TRANSPORT_CMD_NEED_DATA;
+        write (this->data_source.fd, &cmd, 1);
+      }
+
       res = SPA_RESULT_RETURN_ASYNC (cnc.seq);
       break;
     }
@@ -686,8 +691,8 @@ spa_proxy_node_port_use_buffers (SpaNode         *node,
           am.type = d->type;
           am.memfd = d->fd;
           am.flags = d->flags;
-          am.offset = d->offset;
-          am.size = d->size;
+          am.offset = d->mapoffset;
+          am.size = d->maxsize;
           pinos_resource_send_message (this->resource,
                                        PINOS_MESSAGE_ADD_MEM,
                                        &am,
@@ -698,7 +703,7 @@ spa_proxy_node_port_use_buffers (SpaNode         *node,
           break;
         case SPA_DATA_TYPE_MEMPTR:
           b->buffer.datas[j].data = SPA_INT_TO_PTR (b->size);
-          b->size += d->size;
+          b->size += d->maxsize;
           break;
         default:
           b->buffer.datas[j].type = SPA_DATA_TYPE_INVALID;
@@ -863,8 +868,6 @@ static SpaResult
 spa_proxy_node_process_input (SpaNode *node)
 {
   SpaProxy *this;
-  unsigned int i;
-  bool have_error = false;
   uint8_t cmd;
 
   if (node == NULL)
@@ -872,22 +875,29 @@ spa_proxy_node_process_input (SpaNode *node)
 
   this = SPA_CONTAINER_OF (node, SpaProxy, node);
 
-  for (i = 0; i < this->n_inputs; i++) {
-    SpaProxyPort *port = &this->in_ports[i];
-    SpaPortInput *input;
+#if 0
+  {
+    unsigned int i;
+    bool have_error = false;
 
-    if ((input = port->io) == NULL)
-      continue;
+    for (i = 0; i < this->n_inputs; i++) {
+      SpaProxyPort *port = &this->in_ports[i];
+      SpaPortInput *input;
 
-    if (!CHECK_PORT_BUFFER (this, input->buffer_id, port)) {
-      input->status = SPA_RESULT_INVALID_BUFFER_ID;
-      have_error = true;
-      continue;
+      if ((input = port->io) == NULL)
+        continue;
+
+      if (!CHECK_PORT_BUFFER (this, input->buffer_id, port)) {
+        input->status = SPA_RESULT_INVALID_BUFFER_ID;
+        have_error = true;
+        continue;
+      }
+      copy_meta_out (this, port, input->buffer_id);
     }
-    copy_meta_out (this, port, input->buffer_id);
+    if (have_error)
+      return SPA_RESULT_ERROR;
   }
-  if (have_error)
-    return SPA_RESULT_ERROR;
+#endif
 
   cmd = PINOS_TRANSPORT_CMD_HAVE_DATA;
   write (this->data_source.fd, &cmd, 1);
@@ -899,28 +909,37 @@ static SpaResult
 spa_proxy_node_process_output (SpaNode *node)
 {
   SpaProxy *this;
-  unsigned int i;
-  bool have_error = false;
+  uint8_t cmd;
 
   if (node == NULL)
     return SPA_RESULT_INVALID_ARGUMENTS;
 
   this = SPA_CONTAINER_OF (node, SpaProxy, node);
 
-  for (i = 0; i < this->n_outputs; i++) {
-    SpaProxyPort *port = &this->out_ports[i];
-    SpaPortOutput *output;
+#if 0
+  {
+    unsigned int i;
+    bool have_error = false;
 
-    if ((output = port->io) == NULL)
-      continue;
+    for (i = 0; i < this->n_outputs; i++) {
+      SpaProxyPort *port = &this->out_ports[i];
+      SpaPortOutput *output;
 
-    copy_meta_in (this, port, output->buffer_id);
+      if ((output = port->io) == NULL)
+        continue;
 
-    if (output->status != SPA_RESULT_OK)
-      have_error = true;
+      copy_meta_in (this, port, output->buffer_id);
+
+      if (output->status != SPA_RESULT_OK)
+        have_error = true;
+    }
+    if (have_error)
+      return SPA_RESULT_ERROR;
   }
-  if (have_error)
-    return SPA_RESULT_ERROR;
+#endif
+
+  cmd = PINOS_TRANSPORT_CMD_NEED_DATA;
+  write (this->data_source.fd, &cmd, 1);
 
   return SPA_RESULT_OK;
 }
@@ -1052,6 +1071,17 @@ proxy_on_data_fd_events (SpaSource *source)
     }
     if (cmd & PINOS_TRANSPORT_CMD_HAVE_DATA) {
       SpaNodeEventHaveOutput ho;
+      unsigned int i;
+
+      for (i = 0; i < this->n_outputs; i++) {
+        SpaProxyPort *port = &this->out_ports[i];
+        SpaPortOutput *output;
+
+        if ((output = port->io) == NULL)
+          continue;
+
+        copy_meta_in (this, port, output->buffer_id);
+      }
       ho.event.type = SPA_NODE_EVENT_TYPE_HAVE_OUTPUT;
       ho.event.size = sizeof (ho);
       ho.port_id = 0;
diff --git a/pinos/server/link.c b/pinos/server/link.c
index 9ae4f2480..da90e795e 100644
--- a/pinos/server/link.c
+++ b/pinos/server/link.c
@@ -324,10 +324,10 @@ alloc_buffers (PinosLink      *this,
         d->type = SPA_DATA_TYPE_MEMFD;
         d->flags = 0;
         d->fd = mem->fd;
-        d->offset = 0;
-        d->size = mem->size;
-        d->data = mem->ptr;
-        d->chunk->offset = SPA_PTRDIFF (ddp, d->data);
+        d->mapoffset = SPA_PTRDIFF (ddp, mem->ptr);
+        d->maxsize = data_sizes[j];
+        d->data = SPA_MEMBER (mem->ptr, d->mapoffset, void);
+        d->chunk->offset = 0;
         d->chunk->size = data_sizes[j];
         d->chunk->stride = data_strides[j];
         ddp += data_sizes[j];
diff --git a/pinos/server/node.c b/pinos/server/node.c
index d79ce3ace..b4005c74a 100644
--- a/pinos/server/node.c
+++ b/pinos/server/node.c
@@ -328,11 +328,6 @@ on_node_event (SpaNode *node, SpaNodeEvent *event, void *user_data)
       PinosPort *port = this->output_port_map[ho->port_id];
       PinosLink *link;
 
-      if ((res = spa_node_process_output (node)) < 0) {
-        pinos_log_warn ("node %p: got pull error %d, %d", this, res, po->status);
-        break;
-      }
-
       spa_list_for_each (link, &port->rt.links, rt.output_link) {
         size_t offset;
 
@@ -356,6 +351,10 @@ on_node_event (SpaNode *node, SpaNodeEvent *event, void *user_data)
         if ((res = spa_node_port_reuse_buffer (node, ho->port_id, po->buffer_id)) < 0)
           pinos_log_warn ("node %p: error reuse buffer: %d", node, res);
       }
+      if ((res = spa_node_process_output (node)) < 0) {
+        pinos_log_warn ("node %p: got pull error %d, %d", this, res, po->status);
+        break;
+      }
       break;
     }
     case SPA_NODE_EVENT_TYPE_REUSE_BUFFER:
diff --git a/spa/include/spa/buffer.h b/spa/include/spa/buffer.h
index 94eb81bf9..34d5b7a8b 100644
--- a/spa/include/spa/buffer.h
+++ b/spa/include/spa/buffer.h
@@ -174,8 +174,8 @@ typedef struct {
   SpaDataType    type;
   int            flags;
   int            fd;
-  off_t          offset;
-  size_t         size;
+  off_t          mapoffset;
+  size_t         maxsize;
   void          *data;
   SpaChunk      *chunk;
 } SpaData;
diff --git a/spa/include/spa/node.h b/spa/include/spa/node.h
index aaeaad440..e820ce7b8 100644
--- a/spa/include/spa/node.h
+++ b/spa/include/spa/node.h
@@ -568,8 +568,8 @@ struct _SpaNode {
    * Returns: #SPA_RESULT_OK on success
    *          #SPA_RESULT_HAVE_ENOUGH_INPUT when output can be produced.
    */
-  SpaResult   (*process_input)           (SpaNode             *node);
-  SpaResult   (*process_output)          (SpaNode             *node);
+  SpaResult   (*process_input)           (SpaNode *node);
+  SpaResult   (*process_output)          (SpaNode *node);
 
 };
 
diff --git a/spa/lib/debug.c b/spa/lib/debug.c
index 8b3582439..408619e68 100644
--- a/spa/lib/debug.c
+++ b/spa/lib/debug.c
@@ -196,11 +196,11 @@ spa_debug_buffer (const SpaBuffer *buffer)
     fprintf (stderr, "   flags:   %d\n", d->flags);
     fprintf (stderr, "   data:    %p\n", d->data);
     fprintf (stderr, "   fd:      %d\n", d->fd);
-    fprintf (stderr, "   offset:  %zd\n", d->offset);
-    fprintf (stderr, "   maxsize: %zd\n", d->size);
+    fprintf (stderr, "   offset:  %zd\n", d->mapoffset);
+    fprintf (stderr, "   maxsize: %zu\n", d->maxsize);
     fprintf (stderr, "   chunk:   %p\n", d->chunk);
     fprintf (stderr, "    offset: %zd\n", d->chunk->offset);
-    fprintf (stderr, "    size:   %zd\n", d->chunk->size);
+    fprintf (stderr, "    size:   %zu\n", d->chunk->size);
     fprintf (stderr, "    stride: %zd\n", d->chunk->stride);
   }
   return SPA_RESULT_OK;
diff --git a/spa/plugins/alsa/alsa-utils.c b/spa/plugins/alsa/alsa-utils.c
index 4fa72e06f..2adbdcf54 100644
--- a/spa/plugins/alsa/alsa-utils.c
+++ b/spa/plugins/alsa/alsa-utils.c
@@ -268,22 +268,35 @@ pull_frames_queue (SpaALSAState *state,
                    snd_pcm_uframes_t offset,
                    snd_pcm_uframes_t frames)
 {
+  if (spa_list_is_empty (&state->ready)) {
+    SpaNodeEventNeedInput ni;
+
+    ni.event.type = SPA_NODE_EVENT_TYPE_NEED_INPUT;
+    ni.event.size = sizeof (ni);
+    ni.port_id = 0;
+    state->event_cb (&state->node, &ni.event, state->user_data);
+  }
   if (!spa_list_is_empty (&state->ready)) {
     uint8_t *src, *dst;
-    size_t n_bytes;
+    size_t n_bytes, size;
+    off_t offs;
     SpaALSABuffer *b;
 
     b = spa_list_first (&state->ready, SpaALSABuffer, list);
 
-    src = SPA_MEMBER (b->outbuf->datas[0].data, b->outbuf->datas[0].offset + state->ready_offset, uint8_t);
+    offs = SPA_MIN (b->outbuf->datas[0].chunk->offset, b->outbuf->datas[0].maxsize);
+    src = SPA_MEMBER (b->outbuf->datas[0].data, offs, uint8_t);
+    size = SPA_MIN (b->outbuf->datas[0].chunk->size, b->outbuf->datas[0].maxsize - offs);
+
+    src = SPA_MEMBER (src, state->ready_offset, uint8_t);
     dst = SPA_MEMBER (my_areas[0].addr, offset * state->frame_size, uint8_t);
-    n_bytes = SPA_MIN (b->outbuf->datas[0].size - state->ready_offset, frames * state->frame_size);
+    n_bytes = SPA_MIN (size - state->ready_offset, frames * state->frame_size);
     frames = SPA_MIN (frames, n_bytes / state->frame_size);
 
     memcpy (dst, src, n_bytes);
 
     state->ready_offset += n_bytes;
-    if (state->ready_offset >= b->outbuf->datas[0].size) {
+    if (state->ready_offset >= size) {
       SpaNodeEventReuseBuffer rb;
 
       spa_list_remove (&b->list);
@@ -298,7 +311,7 @@ pull_frames_queue (SpaALSAState *state,
       state->ready_offset = 0;
     }
   } else {
-    spa_log_warn (state->log, "underrun");
+    spa_log_warn (state->log, "underrun, want %zd frames", frames);
     snd_pcm_areas_silence (my_areas, offset, state->channels, frames, state->format);
   }
   return frames;
@@ -318,7 +331,7 @@ pull_frames_ringbuffer (SpaALSAState *state,
 
   b = state->ringbuffer;
 
-  src = SPA_MEMBER (b->outbuf->datas[0].data, b->outbuf->datas[0].offset, void);
+  src = b->outbuf->datas[0].data;
   dst = SPA_MEMBER (my_areas[0].addr, offset * state->frame_size, uint8_t);
 
   avail = spa_ringbuffer_get_read_areas (&b->rb->ringbuffer, areas);
@@ -442,8 +455,8 @@ mmap_read (SpaALSAState *state)
     b = spa_list_first (&state->free, SpaALSABuffer, list);
     spa_list_remove (&b->list);
 
-    dest = SPA_MEMBER (b->outbuf->datas[0].data, b->outbuf->datas[0].offset, void);
-    destsize = b->outbuf->datas[0].size;
+    dest = b->outbuf->datas[0].data;
+    destsize = b->outbuf->datas[0].maxsize;
 
     if (b->h) {
       b->h->seq = state->sample_count;
@@ -484,7 +497,9 @@ mmap_read (SpaALSAState *state)
     SpaData *d;
 
     d = b->outbuf->datas;
-    d[0].size = avail * state->frame_size;
+    d[0].chunk->offset = 0;
+    d[0].chunk->size = avail * state->frame_size;
+    d[0].chunk->stride = 0;
 
     spa_list_insert (state->ready.prev, &b->list);
 
diff --git a/spa/plugins/audiomixer/audiomixer.c b/spa/plugins/audiomixer/audiomixer.c
index 654745a83..8645d6ff6 100644
--- a/spa/plugins/audiomixer/audiomixer.c
+++ b/spa/plugins/audiomixer/audiomixer.c
@@ -598,12 +598,12 @@ add_port_data (SpaAudioMixer *this, SpaBuffer *out, SpaAudioMixerPort *port)
 
   while (true) {
     if (op == NULL) {
-      op = (uint8_t*)odatas[oi].data + odatas[oi].offset;
-      os = odatas[oi].size;
+      op = (uint8_t*)odatas[oi].data + odatas[oi].chunk->offset;
+      os = odatas[oi].chunk->size;
     }
     if (ip == NULL) {
-      ip = (uint8_t*)idatas[port->buffer_index].data + idatas[port->buffer_index].offset;
-      is = idatas[port->buffer_index].size;
+      ip = (uint8_t*)idatas[port->buffer_index].data + idatas[port->buffer_index].chunk->offset;
+      is = idatas[port->buffer_index].chunk->size;
       ip += port->buffer_offset;
       is -= port->buffer_offset;
     }
diff --git a/spa/plugins/audiotestsrc/audiotestsrc.c b/spa/plugins/audiotestsrc/audiotestsrc.c
index 11a024b6c..4ddbbe942 100644
--- a/spa/plugins/audiotestsrc/audiotestsrc.c
+++ b/spa/plugins/audiotestsrc/audiotestsrc.c
@@ -690,8 +690,8 @@ spa_audiotestsrc_node_port_use_buffers (SpaNode         *node,
           spa_log_error (this->log, "audiotestsrc %p: invalid memory on buffer %p", this, buffers[i]);
           continue;
         }
-        b->ptr = SPA_MEMBER (d[0].data, d[0].offset, void);
-        b->size = d[0].size;
+        b->ptr = d[0].data;
+        b->size = d[0].maxsize;
         break;
       default:
         break;
diff --git a/spa/plugins/v4l2/v4l2-utils.c b/spa/plugins/v4l2/v4l2-utils.c
index 874fe709d..be3a4c979 100644
--- a/spa/plugins/v4l2/v4l2-utils.c
+++ b/spa/plugins/v4l2/v4l2-utils.c
@@ -117,7 +117,7 @@ spa_v4l2_clear_buffers (SpaV4l2Source *this)
     }
     if (b->allocated) {
       if (b->outbuf->datas[0].data)
-        munmap (b->outbuf->datas[0].data, b->outbuf->datas[0].size);
+        munmap (b->outbuf->datas[0].data, b->outbuf->datas[0].maxsize);
       if (b->outbuf->datas[0].fd != -1)
         close (b->outbuf->datas[0].fd);
       b->outbuf->datas[0].type = SPA_DATA_TYPE_INVALID;
@@ -973,7 +973,7 @@ spa_v4l2_use_buffers (SpaV4l2Source *this, SpaBuffer **buffers, uint32_t n_buffe
           continue;
         }
         b->v4l2_buffer.m.userptr = (unsigned long) d[0].data;
-        b->v4l2_buffer.length = d[0].size;
+        b->v4l2_buffer.length = d[0].maxsize;
         break;
       case SPA_DATA_TYPE_DMABUF:
         b->v4l2_buffer.m.fd = d[0].fd;
@@ -1047,8 +1047,8 @@ mmap_init (SpaV4l2Source   *this,
     }
 
     d = buffers[i]->datas;
-    d[0].offset = 0;
-    d[0].size = b->v4l2_buffer.length;
+    d[0].mapoffset = 0;
+    d[0].maxsize = b->v4l2_buffer.length;
     d[0].chunk->offset = 0;
     d[0].chunk->size = b->v4l2_buffer.length;
     d[0].chunk->stride = state->fmt.fmt.pix.bytesperline;
diff --git a/spa/plugins/videotestsrc/videotestsrc.c b/spa/plugins/videotestsrc/videotestsrc.c
index 292882ab6..66baec1a5 100644
--- a/spa/plugins/videotestsrc/videotestsrc.c
+++ b/spa/plugins/videotestsrc/videotestsrc.c
@@ -657,7 +657,7 @@ spa_videotestsrc_node_port_use_buffers (SpaNode         *node,
           spa_log_error (this->log, "videotestsrc %p: invalid memory on buffer %p", this, buffers[i]);
           continue;
         }
-        b->ptr = SPA_MEMBER (d[0].data, d[0].offset, void);
+        b->ptr = SPA_MEMBER (d[0].data, d[0].chunk->offset, void);
         b->stride = d[0].chunk->stride;
         break;
       default:
diff --git a/spa/plugins/volume/volume.c b/spa/plugins/volume/volume.c
index 4a64e8d4a..4eb7a9587 100644
--- a/spa/plugins/volume/volume.c
+++ b/spa/plugins/volume/volume.c
@@ -582,10 +582,10 @@ spa_volume_node_process_output (SpaNode *node)
     sd = &sbuf->datas[si];
     dd = &dbuf->datas[di];
 
-    src = (uint16_t*) ((uint8_t*)sd->data + sd->offset + soff);
-    dst = (uint16_t*) ((uint8_t*)dd->data + dd->offset + doff);
+    src = (uint16_t*) ((uint8_t*)sd->data + sd->chunk->offset + soff);
+    dst = (uint16_t*) ((uint8_t*)dd->data + dd->chunk->offset + doff);
 
-    n_bytes = SPA_MIN (sd->size - soff, dd->size - doff);
+    n_bytes = SPA_MIN (sd->chunk->size - soff, dd->chunk->size - doff);
     n_samples = n_bytes / sizeof (uint16_t);
 
     for (i = 0; i < n_samples; i++)
@@ -594,11 +594,11 @@ spa_volume_node_process_output (SpaNode *node)
     soff += n_bytes;
     doff += n_bytes;
 
-    if (soff >= sd->size) {
+    if (soff >= sd->chunk->size) {
       si++;
       soff = 0;
     }
-    if (doff >= dd->size) {
+    if (doff >= dd->chunk->size) {
       di++;
       doff = 0;
     }