rtpbuffer: Add functions to add RFC 5285 header extensions to GstBufferLists

Add functions to add header extensions to buffer lists, these functions only modify
the header part of the buffer lists, so the data is not copied.

docs/libs/gst-plugins-base-libs-sections.txt

@@ -1359,12 +1359,13 @@ gst_rtp_buffer_list_set_timestamp
 
 gst_rtp_buffer_get_extension_onebyte_header
 gst_rtp_buffer_get_extension_twobytes_header
-
 gst_rtp_buffer_add_extension_onebyte_header
 gst_rtp_buffer_add_extension_twobytes_header
 
 gst_rtp_buffer_list_get_extension_onebyte_header
 gst_rtp_buffer_list_get_extension_twobytes_header
+gst_rtp_buffer_list_add_extension_onebyte_header
+gst_rtp_buffer_list_add_extension_twobytes_header
 </SECTION>
 
 # rtsp

gst-libs/gst/rtp/gstrtpbuffer.c

@@ -1543,6 +1543,43 @@ gst_rtp_buffer_get_extension_twobytes_header (GstBuffer * buffer,
   return FALSE;
 }
 
+static guint
+get_onebyte_header_end_offset (guint8 * pdata, guint wordlen)
+{
+  guint offset = 0;
+  guint bytelen = wordlen * 4;
+  guint paddingcount = 0;
+
+  while (offset + 1 < bytelen) {
+    guint8 read_id, read_len;
+
+    read_id = GST_READ_UINT8 (pdata + offset) >> 4;
+    read_len = (GST_READ_UINT8 (pdata + offset) & 0x0F) + 1;
+    offset += 1;
+
+    /* ID 0 means its padding, skip */
+    if (read_id == 0) {
+      paddingcount++;
+      continue;
+    }
+
+    paddingcount = 0;
+
+    /* ID 15 is special and means we should stop parsing */
+    /* It also means we can't add an extra packet */
+    if (read_id == 15)
+      return 0;
+
+    /* Ignore extension headers where the size does not fit */
+    if (offset + read_len > bytelen)
+      return 0;
+
+    offset += read_len;
+  }
+
+  return offset - paddingcount;
+}
+
 /**
  * gst_rtp_buffer_add_extension_onebyte_header:
  * @buffer: the buffer
@@ -1590,32 +1627,11 @@ gst_rtp_buffer_add_extension_onebyte_header (GstBuffer * buffer, guint8 id,
     if (bits != 0xBEDE)
       return FALSE;
 
-    while (offset + 1 < bytelen) {
-      guint8 read_id, read_len;
-
-      read_id = GST_READ_UINT8 (pdata + offset) >> 4;
-      read_len = (GST_READ_UINT8 (pdata + offset) & 0x0F) + 1;
-      offset += 1;
-
-      /* ID 0 means its padding, skip */
-      if (read_id == 0)
-        continue;
-
-      /* ID 15 is special and means we should stop parsing */
-      /* It also means we can't add an extra packet */
-      if (read_id == 15)
-        return FALSE;
-
-      /* Ignore extension headers where the size does not fit */
-      if (offset + read_len > bytelen)
-        return FALSE;
-
-      offset += read_len;
-
-    }
+    offset = get_onebyte_header_end_offset (pdata, wordlen);
+    if (offset == 0)
+      return FALSE;
 
     nextext = pdata + offset;
-
     offset = nextext - GST_BUFFER_DATA (buffer);
 
     /* Don't add extra header if there isn't enough space */
@@ -1652,6 +1668,41 @@ gst_rtp_buffer_add_extension_onebyte_header (GstBuffer * buffer, guint8 id,
   return TRUE;
 }
 
+
+static guint
+get_twobytes_header_end_offset (guint8 * pdata, guint wordlen)
+{
+  guint offset = 0;
+  guint bytelen = wordlen * 4;
+  guint paddingcount = 0;
+
+  while (offset + 2 < bytelen) {
+    guint8 read_id, read_len;
+
+    read_id = GST_READ_UINT8 (pdata + offset);
+    offset += 1;
+
+    /* ID 0 means its padding, skip */
+    if (read_id == 0) {
+      paddingcount++;
+      continue;
+    }
+
+    paddingcount = 0;
+
+    read_len = GST_READ_UINT8 (pdata + offset);
+    offset += 1;
+
+    /* Ignore extension headers where the size does not fit */
+    if (offset + read_len > bytelen)
+      return 0;
+
+    offset += read_len;
+  }
+
+  return offset - paddingcount;
+}
+
 /**
  * gst_rtp_buffer_add_extension_twobytes_header:
  * @buffer: the buffer
@@ -1700,25 +1751,7 @@ gst_rtp_buffer_add_extension_twobytes_header (GstBuffer * buffer,
     if (bits != ((0x100 << 4) | (appbits & 0x0f)))
       return FALSE;
 
-    while (offset + 2 < bytelen) {
-      guint8 read_id, read_len;
-
-      read_id = GST_READ_UINT8 (pdata + offset);
-      offset += 1;
-
-      /* ID 0 means its padding, skip */
-      if (read_id == 0)
-        continue;
-
-      read_len = GST_READ_UINT8 (pdata + offset);
-      offset += 1;
-
-      /* Ignore extension headers where the size does not fit */
-      if (offset + read_len > bytelen)
-        return FALSE;
-
-      offset += read_len;
-    }
+    offset = get_twobytes_header_end_offset (pdata, wordlen);
 
     nextext = pdata + offset;
 
@@ -1827,3 +1860,165 @@ gst_rtp_buffer_list_get_extension_twobytes_header (GstBufferList * bufferlist,
   return gst_rtp_buffer_get_extension_twobytes_header (buffer, appbits, id,
       nth, data, size);
 }
+
+/**
+ * gst_rtp_buffer_list_add_extension_onebyte_header:
+ * @it: a #GstBufferListIterator pointing right after the #GstBuffer where
+ * the header extension should be added
+ * @id: The ID of the header extension (between 1 and 14).
+ * @data: location for data
+ * @size: the size of the data in bytes
+ *
+ * Adds a RFC 5285 header extension with a one byte header to the end of the
+ * RTP header. If there is already a RFC 5285 header extension with a one byte
+ * header, the new extension will be appended.
+ * It will not work if there is already a header extension that does not follow
+ * the mecanism described in RFC 5285 or if there is a header extension with
+ * a two bytes header as described in RFC 5285. In that case, use
+ * gst_rtp_buffer_list_add_extension_twobytes_header()
+ *
+ * This function will not modify the data section of the RTP buffer, only
+ * the header.
+ *
+ * Returns: %TRUE if header extension could be added
+ *
+ * Since: 0.10.31
+ */
+
+gboolean
+gst_rtp_buffer_list_add_extension_onebyte_header (GstBufferListIterator * it,
+    guint8 id, gpointer data, guint size)
+{
+  GstBuffer *buffer;
+  guint16 bits;
+  guint8 *pdata;
+  guint wordlen;
+  gboolean retval;
+  guint endoffset = 0;
+
+  g_return_val_if_fail (gst_buffer_list_iterator_n_buffers (it) == 1, FALSE);
+  g_return_val_if_fail (id > 0 && id < 15, FALSE);
+  g_return_val_if_fail (size >= 1 && size <= 16, FALSE);
+
+  buffer = gst_buffer_list_iterator_steal (it);
+
+  if (GST_RTP_HEADER_EXTENSION (GST_BUFFER_DATA (buffer))) {
+    gst_rtp_buffer_get_extension_data (buffer, &bits, (gpointer) & pdata,
+        &wordlen);
+
+    if (bits != 0xBEDE)
+      return FALSE;
+
+    endoffset = get_onebyte_header_end_offset (pdata, wordlen);
+    if (endoffset == 0)
+      return FALSE;
+    endoffset += pdata - GST_BUFFER_DATA (buffer);
+  } else {
+    endoffset = GST_BUFFER_SIZE (buffer) + 4;
+  }
+
+  if (endoffset + size + 1 > GST_BUFFER_SIZE (buffer)) {
+    guint newsize;
+    GstBuffer *newbuffer;
+
+    newsize = endoffset + size + 1;
+    if (newsize % 4)
+      newsize += 4 - (newsize % 4);
+    newbuffer = gst_buffer_new_and_alloc (newsize);
+    memcpy (GST_BUFFER_DATA (newbuffer), GST_BUFFER_DATA (buffer),
+        GST_BUFFER_SIZE (buffer));
+    gst_buffer_copy_metadata (newbuffer, buffer, GST_BUFFER_COPY_ALL);
+    gst_buffer_unref (buffer);
+    buffer = newbuffer;
+  } else {
+    buffer = gst_buffer_make_writable (buffer);
+  }
+
+  retval = gst_rtp_buffer_add_extension_onebyte_header (buffer, id, data, size);
+
+  gst_buffer_list_iterator_take (it, buffer);
+
+  return retval;
+}
+
+/**
+ * gst_rtp_buffer_list_add_extension_twobytes_header:
+ * @it: a #GstBufferListIterator pointing right after the #GstBuffer where
+ * the header extension should be added
+ * @appbits: Application specific bits
+ * @id: The ID of the header extension
+ * @data: location for data
+ * @size: the size of the data in bytes
+ *
+ * Adds a RFC 5285 header extension with a two bytes header to the end of the
+ * RTP header. If there is already a RFC 5285 header extension with a two bytes
+ * header, the new extension will be appended.
+ * It will not work if there is already a header extension that does not follow
+ * the mecanism described in RFC 5285 or if there is a header extension with
+ * a one byte header as described in RFC 5285. In that case, use
+ * gst_rtp_buffer_add_extension_onebyte_header()
+ *
+ * This function will not modify the data section of the RTP buffer, only
+ * the header.
+ *
+ * Returns: %TRUE if header extension could be added
+ *
+ * Since: 0.10.31
+ */
+
+gboolean
+gst_rtp_buffer_list_add_extension_twobytes_header (GstBufferListIterator * it,
+    guint8 appbits, guint8 id, gpointer data, guint size)
+{
+  GstBuffer *buffer;
+  guint16 bits;
+  guint8 *pdata;
+  guint wordlen;
+  gboolean retval;
+  guint endoffset;
+
+  g_return_val_if_fail ((appbits & 0xF0) == 0, FALSE);
+  g_return_val_if_fail (size < 256, FALSE);
+  g_return_val_if_fail (gst_buffer_list_iterator_n_buffers (it) == 1, FALSE);
+
+  buffer = gst_buffer_list_iterator_steal (it);
+
+  if (GST_RTP_HEADER_EXTENSION (GST_BUFFER_DATA (buffer))) {
+    gst_rtp_buffer_get_extension_data (buffer, &bits, (gpointer) & pdata,
+        &wordlen);
+
+    if (bits != ((0x100 << 4) | (appbits & 0x0f)))
+      return FALSE;
+
+    endoffset = get_twobytes_header_end_offset (pdata, wordlen);
+    if (endoffset == 0)
+      return FALSE;
+    endoffset += pdata - GST_BUFFER_DATA (buffer);
+  } else {
+    endoffset = GST_BUFFER_SIZE (buffer) + 4;
+  }
+
+  if (endoffset + size + 2 > GST_BUFFER_SIZE (buffer)) {
+    guint newsize;
+    GstBuffer *newbuffer;
+
+    newsize = endoffset + size + 2;
+    if (newsize % 4)
+      newsize += 4 - newsize % 4;
+    newbuffer = gst_buffer_new_and_alloc (newsize);
+    memcpy (GST_BUFFER_DATA (newbuffer), GST_BUFFER_DATA (buffer),
+        GST_BUFFER_SIZE (buffer));
+    gst_buffer_copy_metadata (newbuffer, buffer, GST_BUFFER_COPY_ALL);
+    gst_buffer_unref (buffer);
+    buffer = newbuffer;
+  } else {
+    buffer = gst_buffer_make_writable (buffer);
+  }
+
+  retval = gst_rtp_buffer_add_extension_twobytes_header (buffer, appbits, id,
+      data, size);
+
+  gst_buffer_list_iterator_take (it, buffer);
+
+  return retval;
+}

gst-libs/gst/rtp/gstrtpbuffer.h

@@ -146,6 +146,17 @@ gboolean       gst_rtp_buffer_list_get_extension_twobytes_header (GstBufferList
                                                                   gpointer * data,
                                                                   guint * size);
 
+gboolean       gst_rtp_buffer_list_add_extension_onebyte_header (GstBufferListIterator * it,
+                                                                  guint8 id,
+                                                                  gpointer data,
+                                                                  guint size);
+gboolean       gst_rtp_buffer_list_add_extension_twobytes_header (GstBufferListIterator * it,
+                                                                  guint8 appbits,
+                                                                  guint8 id,
+                                                                  gpointer data,
+                                                                  guint size);
+
+
 G_END_DECLS
 
 #endif /* __GST_RTPBUFFER_H__ */