Fix: GStreamer plugins wrong memory buffer size (#1167)

In the st20tx and st30tx GStreamer plugins, the memory
buffer size was incorrectly taken from the
GstBuffer size which includes the combined size
of all GstMemory elements in the buffer, as we
Allow multiple GstMemory elements in the buffer
This would result in a wrong buffer parsing.

Fix via taking the size from the memory map.

Author: DawidWesierski4

ecosystem/gstreamer_plugin/gst_mtl_st20p_tx.c

@@ -457,8 +457,7 @@ static gboolean gst_mtl_st20p_tx_sink_event(GstPad* pad, GstObject* parent,
 static GstFlowReturn gst_mtl_st20p_tx_chain(GstPad* pad, GstObject* parent,
                                             GstBuffer* buf) {
   Gst_Mtl_St20p_Tx* sink = GST_MTL_ST20P_TX(parent);
-  gint buffer_size = gst_buffer_get_size(buf);
-  gint buffer_n = gst_buffer_n_memory(buf);
+  gint buffer_size, buffer_n = gst_buffer_n_memory(buf);
   struct st_frame* frame = NULL;
   gint frame_size = sink->frame_size;
   GstMemory* gst_buffer_memory;
@@ -481,18 +480,20 @@ static GstFlowReturn gst_mtl_st20p_tx_chain(GstPad* pad, GstObject* parent,
     return GST_FLOW_ERROR;
   }
 
-  if (buffer_size != frame_size) {
-    GST_ERROR("Buffer size %d does not match frame size %d", buffer_size, frame_size);
-    return GST_FLOW_ERROR;
-  }
-
   for (int i = 0; i < buffer_n; i++) {
     gst_buffer_memory = gst_buffer_peek_memory(buf, i);
 
     if (!gst_memory_map(gst_buffer_memory, &map_info, GST_MAP_READ)) {
       GST_ERROR("Failed to map memory");
       return GST_FLOW_ERROR;
     }
+    buffer_size = map_info.size;
+
+    if (buffer_size < frame_size) {
+      GST_ERROR("Buffer size %d is smaller than frame size %d", buffer_size, frame_size);
+      gst_memory_unmap(gst_buffer_memory, &map_info);
+      return GST_FLOW_ERROR;
+    }
 
     frame = st20p_tx_get_frame(sink->tx_handle);
     if (!frame) {

ecosystem/gstreamer_plugin/gst_mtl_st30p_tx.c

@@ -527,14 +527,14 @@ static GstFlowReturn gst_mtl_st30p_tx_chain(GstPad* pad, GstObject* parent,
   }
 
   for (int i = 0; i < buffer_n; i++) {
-    bytes_to_write = gst_buffer_get_size(buf);
     gst_buffer_memory = gst_buffer_peek_memory(buf, i);
 
     if (!gst_memory_map(gst_buffer_memory, &map_info, GST_MAP_READ)) {
       GST_ERROR("Failed to map memory");
       return GST_FLOW_ERROR;
     }
 
+    bytes_to_write = map_info.size;
     /* This could be done with GstAdapter */
     while (bytes_to_write > 0) {
       frame = mtl_st30p_fetch_frame(sink);
@@ -566,6 +566,7 @@ static GstFlowReturn gst_mtl_st30p_tx_chain(GstPad* pad, GstObject* parent,
     }
     gst_memory_unmap(gst_buffer_memory, &map_info);
   }
+
   gst_buffer_unref(buf);
   return GST_FLOW_OK;
 }