mpegtsmux: fix buffer size mismatch in M2TS mode

In M2TS mode, we need an extra 4 bytes in the buffer, so need
to ensure the buffer can contain these. The allocation site
does not know the mode, so this is done in all cases.

1 files changed, 25 insertions, 1 deletions

diff --git a/gst/mpegtsmux/tsmux/tsmux.c b/gst/mpegtsmux/tsmux/tsmux.c
index 638de15aa..ee2870498 100644
--- a/gst/mpegtsmux/tsmux/tsmux.c
+++ b/gst/mpegtsmux/tsmux/tsmux.c
@@ -853,6 +853,7 @@ tsmux_section_write_packet (GstMpegtsSectionType * type,
   gsize data_size = 0;
   gsize payload_written;
   guint len = 0, offset = 0, payload_len = 0;
+  guint extra_alloc_bytes = 0;
 
   g_return_val_if_fail (section != NULL, FALSE);
   g_return_val_if_fail (mux != NULL, FALSE);
@@ -907,12 +908,35 @@ tsmux_section_write_packet (GstMpegtsSectionType * type,
     TS_DEBUG ("Creating packet buffer at offset "
         "%" G_GSIZE_FORMAT " with length %u", payload_written, payload_len);
 
+    /* If in M2TS mode, we will need to resize to 4 bytes after the end
+       of the buffer. For performance reasons, we will now try to include
+       4 extra bytes from the source buffer, then resize down, to avoid
+       having an extra 4 byte GstMemory appended. If the source buffer
+       does not have enough data for this, a new GstMemory will be used */
+    if (gst_buffer_get_size (section_buffer) - (payload_written +
+            payload_len) >= 4) {
+      /* enough space */
+      extra_alloc_bytes = 4;
+    }
     packet_buffer = gst_buffer_copy_region (section_buffer, GST_BUFFER_COPY_ALL,
-        payload_written, payload_len);
+        payload_written, payload_len + extra_alloc_bytes);
 
     /* Prepend the header to the section data */
     gst_buffer_prepend_memory (packet_buffer, mem);
 
+    /* add an extra 4 bytes if it could not be reserved already */
+    if (extra_alloc_bytes == 4) {
+      /* we allocated those already, resize */
+      gst_buffer_set_size (packet_buffer,
+          gst_buffer_get_size (packet_buffer) - extra_alloc_bytes);
+    } else {
+      void *ptr = g_malloc (4);
+      GstMemory *extra =
+          gst_memory_new_wrapped (GST_MEMORY_FLAG_READONLY, ptr, 4, 0, 0, ptr,
+          g_free);
+      gst_buffer_append_memory (packet_buffer, extra);
+    }
+
     TS_DEBUG ("Writing %d bytes to section. %d bytes remaining",
         len, section->pi.stream_avail - len);