qtdemux: Ensure that raw audio and video have properly aligned buffers

That is, aligned to the basic type for audio and to 32 bytes for video.
Fixes crashes if the raw buffers are passed to SIMD processing functions.

https://bugzilla.gnome.org/show_bug.cgi?id=774428

gst/isomp4/qtdemux.c

@@ -298,6 +298,8 @@ struct _QtDemuxStream
   GstAllocator *allocator;
   GstAllocationParams params;
 
+  gsize alignment;
+
   /* when a discontinuity is pending */
   gboolean discont;
 
@@ -1848,6 +1850,7 @@ _create_stream (void)
   stream->n_samples_moof = 0;
   stream->duration_moof = 0;
   stream->duration_last_moof = 0;
+  stream->alignment = 1;
   g_queue_init (&stream->protection_scheme_event_queue);
   return stream;
 }
@@ -5127,6 +5130,44 @@ clipped:
   }
 }
 
+static GstBuffer *
+gst_qtdemux_align_buffer (GstQTDemux * demux,
+    GstBuffer * buffer, gsize alignment)
+{
+  GstMapInfo map;
+
+  gst_buffer_map (buffer, &map, GST_MAP_READ);
+
+  if (map.size < sizeof (guintptr)) {
+    gst_buffer_unmap (buffer, &map);
+    return buffer;
+  }
+
+  if (((guintptr) map.data) & (alignment - 1)) {
+    GstBuffer *new_buffer;
+    GstAllocationParams params = { 0, alignment - 1, 0, 0, };
+
+    new_buffer = gst_buffer_new_allocate (NULL,
+        gst_buffer_get_size (buffer), &params);
+
+    /* Copy data "by hand", so ensure alignment is kept: */
+    gst_buffer_fill (new_buffer, 0, map.data, map.size);
+
+    gst_buffer_copy_into (new_buffer, buffer, GST_BUFFER_COPY_METADATA, 0, -1);
+    GST_DEBUG_OBJECT (demux,
+        "We want output aligned on %" G_GSIZE_FORMAT ", reallocated",
+        alignment);
+
+    gst_buffer_unmap (buffer, &map);
+    gst_buffer_unref (buffer);
+
+    return new_buffer;
+  }
+
+  gst_buffer_unmap (buffer, &map);
+  return buffer;
+}
+
 /* the input buffer metadata must be writable,
  * but time/duration etc not yet set and need not be preserved */
 static GstBuffer *
@@ -5248,6 +5289,8 @@ gst_qtdemux_decorate_and_push_buffer (GstQTDemux * qtdemux,
       GST_BUFFER_FLAG_UNSET (buf, GST_BUFFER_FLAG_DISCONT);
     }
 
+    if (stream->alignment > 1)
+      buffer = gst_qtdemux_align_buffer (qtdemux, buffer, stream->alignment);
     gst_pad_push (stream->pad, buffer);
 
     stream->buffers = g_slist_delete_link (stream->buffers, stream->buffers);
@@ -5351,6 +5394,9 @@ gst_qtdemux_decorate_and_push_buffer (GstQTDemux * qtdemux,
     }
   }
 
+  if (stream->alignment > 1)
+    buf = gst_qtdemux_align_buffer (qtdemux, buf, stream->alignment);
+
   ret = gst_pad_push (stream->pad, buf);
 
   if (GST_CLOCK_TIME_IS_VALID (pts) && GST_CLOCK_TIME_IS_VALID (duration)) {
@@ -13137,6 +13183,7 @@ qtdemux_video_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
       caps = gst_caps_new_empty_simple ("video/x-raw");
       gst_caps_set_simple (caps, "format", G_TYPE_STRING, "RGB8P", NULL);
       _codec ("Windows Raw RGB");
+      stream->alignment = 32;
       break;
     case FOURCC_raw_:
     {
@@ -13500,11 +13547,24 @@ qtdemux_video_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
 
     /* enable clipping for raw video streams */
     stream->need_clip = TRUE;
+    stream->alignment = 32;
   }
 
   return caps;
 }
 
+static guint
+round_up_pow2 (guint n)
+{
+  n = n - 1;
+  n = n | (n >> 1);
+  n = n | (n >> 2);
+  n = n | (n >> 4);
+  n = n | (n >> 8);
+  n = n | (n >> 16);
+  return n + 1;
+}
+
 static GstCaps *
 qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
     guint32 fourcc, const guint8 * data, int len, gchar ** codec_name)
@@ -13547,6 +13607,8 @@ qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
       caps = gst_caps_new_simple ("audio/x-raw",
           "format", G_TYPE_STRING, gst_audio_format_to_string (format),
           "layout", G_TYPE_STRING, "interleaved", NULL);
+      stream->alignment = GST_ROUND_UP_8 (depth);
+      stream->alignment = round_up_pow2 (stream->alignment);
       break;
     }
     case GST_MAKE_FOURCC ('f', 'l', '6', '4'):
@@ -13554,12 +13616,14 @@ qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
       caps = gst_caps_new_simple ("audio/x-raw",
           "format", G_TYPE_STRING, "F64BE",
           "layout", G_TYPE_STRING, "interleaved", NULL);
+      stream->alignment = 8;
       break;
     case GST_MAKE_FOURCC ('f', 'l', '3', '2'):
       _codec ("Raw 32-bit floating-point audio");
       caps = gst_caps_new_simple ("audio/x-raw",
           "format", G_TYPE_STRING, "F32BE",
           "layout", G_TYPE_STRING, "interleaved", NULL);
+      stream->alignment = 4;
       break;
     case FOURCC_in24:
       _codec ("Raw 24-bit PCM audio");
@@ -13568,12 +13632,14 @@ qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
       caps = gst_caps_new_simple ("audio/x-raw",
           "format", G_TYPE_STRING, "S24BE",
           "layout", G_TYPE_STRING, "interleaved", NULL);
+      stream->alignment = 4;
       break;
     case GST_MAKE_FOURCC ('i', 'n', '3', '2'):
       _codec ("Raw 32-bit PCM audio");
       caps = gst_caps_new_simple ("audio/x-raw",
           "format", G_TYPE_STRING, "S32BE",
           "layout", G_TYPE_STRING, "interleaved", NULL);
+      stream->alignment = 4;
       break;
     case FOURCC_ulaw:
       _codec ("Mu-law audio");
@@ -13753,6 +13819,8 @@ qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
             "format", G_TYPE_STRING, gst_audio_format_to_string (format),
             "layout", G_TYPE_STRING, (flags & FLAG_IS_NON_INTERLEAVED) ?
             "non-interleaved" : "interleaved", NULL);
+        stream->alignment = GST_ROUND_UP_8 (depth);
+        stream->alignment = round_up_pow2 (stream->alignment);
       } else {
         if (width == 0)
           width = 32;
@@ -13771,6 +13839,7 @@ qtdemux_audio_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
             "format", G_TYPE_STRING, gst_audio_format_to_string (format),
             "layout", G_TYPE_STRING, (flags & FLAG_IS_NON_INTERLEAVED) ?
             "non-interleaved" : "interleaved", NULL);
+        stream->alignment = width / 8;
       }
       break;
     }