Riff, EBML, fourcc etc. work. Not fully finished, but better than what we used to have and definately worth a first b...

Original commit message from CVS:
Riff, EBML, fourcc etc. work. Not fully finished, but better than
what we used to have and definately worth a first broad testing.

I've revived rifflib. Rifflib used to be a bytestream-for-riff, which
just dup'ed bytestream. I've rewritten rifflib to be a modern riff-
chunk parser that uses bytestream fully, plus adds some extra functions
so that riff file parsing becomes extremely easy. It also contains some
small usability functions for strh/strf and metadata parsing. Note that
it doesn't use the new tagging yet, that's a TODO.

Avidemux has been rewritten to use this. I think we all agreed that
avidemux was pretty much a big mess, which is because it used all
sort of bytestream magic all around the place. It was just ugly.
This is a lot nicer, very complete and safe. I think this is far more
robust than what the old avidemux could ever have been. Of course, it
might contain bugs, please let me know.

EBML writing has also been implemented. This is useful for matroska.
I'm intending to modify avidemux (with a riffwriter) similarly. Maybe
I'll change wavparse/-enc too to use rifflib.

Lastly, several plugins have been modified to use rifflib's fourcc
parsing instead of their own. this puts fourcc parsing in one central
place, which should make it a lot simpler to add new fourccs. We might
want to move this to its own lib instead of rifflib.

Enjoy!

1 files changed, 101 insertions, 26 deletions

diff --git a/gst/matroska/ebml-read.c b/gst/matroska/ebml-read.c
index a6b9225d..67b9b5f3 100644
--- a/gst/matroska/ebml-read.c
+++ b/gst/matroska/ebml-read.c
@@ -157,7 +157,20 @@ gst_ebml_read_element_id (GstEbmlRead *ebml,
   guint32 total;
 
   if (gst_bytestream_peek_bytes (ebml->bs, &data, 1) != 1) {
-    /*gst_element_error (GST_ELEMENT (ebml), "Read error");*/
+    GstEvent *event = NULL;
+    guint32 remaining;
+
+    /* Here, we might encounter EOS */
+    gst_bytestream_get_status (ebml->bs, &remaining, &event);
+    if (event && GST_EVENT_TYPE (event) == GST_EVENT_EOS) {
+      gst_pad_event_default (ebml->sinkpad, event);
+    } else {
+      guint64 pos = gst_bytestream_tell (ebml->bs);
+      gst_event_unref (event);
+      gst_element_error (GST_ELEMENT (ebml),
+			 "Read error at position %llu (0x%llx)",
+			 pos, pos);
+    }
     return -1;
   }
   total = data[0];
@@ -166,13 +179,18 @@ gst_ebml_read_element_id (GstEbmlRead *ebml,
     len_mask >>= 1;
   }
   if (read > 4) {
+    guint64 pos = gst_bytestream_tell (ebml->bs);
     gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid EBML ID size tag (0x%x)", data[0]);
+		       "Invalid EBML ID size tag (0x%x) at position %llu (0x%llx)",
+		       data[0], pos, pos);
     return -1;
   }
 
   if (gst_bytestream_peek_bytes (ebml->bs, &data, read) != read) {
-    /*gst_element_error (GST_ELEMENT (ebml), "Read error");*/
+    guint64 pos = gst_bytestream_tell (ebml->bs);
+    gst_element_error (GST_ELEMENT (ebml),
+		       "Read error at position %llu (0x%llx)",
+		       pos, pos);
     return -1;
   }
   while (n < read)
@@ -201,7 +219,10 @@ gst_ebml_read_element_length (GstEbmlRead *ebml,
   guint64 total;
                                                                                 
   if (gst_bytestream_peek_bytes (ebml->bs, &data, 1) != 1) {
-    /*gst_element_error (GST_ELEMENT (ebml), "Read error");*/
+    guint64 pos = gst_bytestream_tell (ebml->bs);
+    gst_element_error (GST_ELEMENT (ebml),
+		       "Read error at position %llu (0x%llx)",
+		       pos, pos);
     return -1;
   }
   total = data[0];
@@ -210,15 +231,20 @@ gst_ebml_read_element_length (GstEbmlRead *ebml,
     len_mask >>= 1;
   }
   if (read > 8) {
+    guint64 pos = gst_bytestream_tell (ebml->bs);
     gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid EBML length size tag (0x%x)", data[0]);
+		       "Invalid EBML length size tag (0x%x) at position %llu (0x%llx)",
+		       data[0], pos, pos);
     return -1;
   }
 
   if ((total &= (len_mask - 1)) == len_mask - 1)
     num_ffs++;
   if (gst_bytestream_peek_bytes (ebml->bs, &data, read) != read) {
-    /*gst_element_error (GST_ELEMENT (ebml), "Read error");*/
+    guint64 pos = gst_bytestream_tell (ebml->bs);
+    gst_element_error (GST_ELEMENT (ebml),
+		       "Read error at position %llu (0x%llx)",
+		       pos, pos);
     return -1;
   }
   while (n < read) {
@@ -228,12 +254,6 @@ gst_ebml_read_element_length (GstEbmlRead *ebml,
     n++;
   }
 
-  if (!total) {
-    gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid length 0");
-    return -1;
-  }
-
   if (read == num_ffs)
     *length = G_MAXUINT64;
   else
@@ -254,7 +274,10 @@ gst_ebml_read_element_data (GstEbmlRead *ebml,
   GstBuffer *buf = NULL;
 
   if (gst_bytestream_peek (ebml->bs, &buf, length) != length) {
-    /*gst_element_error (GST_ELEMENT (ebml), "Read error");*/
+    guint64 pos = gst_bytestream_tell (ebml->bs);
+    gst_element_error (GST_ELEMENT (ebml),
+		       "Read error at position %llu (0x%llx)",
+		       pos, pos);
     if (buf)
       gst_buffer_unref (buf);
     return NULL;
@@ -276,16 +299,12 @@ gst_ebml_peek_id (GstEbmlRead *ebml,
 		  guint       *level_up)
 {
   guint32 id;
-  guint my_level_up;
 
-  g_return_val_if_fail (level_up != NULL, 0);
+  g_assert (level_up);
 
-  if (gst_ebml_read_element_id (ebml, &id, &my_level_up) < 0)
+  if (gst_ebml_read_element_id (ebml, &id, level_up) < 0)
     return 0;
 
-  if (level_up)
-    *level_up = my_level_up;
-
   return id;
 }
 
@@ -293,11 +312,47 @@ gst_ebml_peek_id (GstEbmlRead *ebml,
  * Seek to a given offset.
  */
 
-void
+GstEvent *
 gst_ebml_read_seek (GstEbmlRead *ebml,
 		    guint64      offset)
 {
-  gst_bytestream_seek (ebml->bs, offset, GST_SEEK_METHOD_SET);
+  guint32 remaining;
+  GstEvent *event;
+  guchar *data;
+
+  /* first, flush remaining buffers */
+  gst_bytestream_get_status (ebml->bs, &remaining, &event);
+  if (event) {
+    g_warning ("Unexpected event before seek");
+    gst_event_unref (event);
+  }
+  if (remaining)
+    gst_bytestream_flush_fast (ebml->bs, remaining);
+
+  /* now seek */
+  if (!gst_bytestream_seek (ebml->bs, offset, GST_SEEK_METHOD_SET)) {
+    gst_element_error (GST_ELEMENT (ebml),
+		       "Seek to position %llu (0x%llx) failed",
+		       offset, offset);
+    return NULL;
+  }
+
+  /* and now, peek a new byte. This will fail because there's a
+   * pending event. Then, take the event and return it. */
+  if (gst_bytestream_peek_bytes (ebml->bs, &data, 1))
+    g_warning ("Unexpected data after seek");
+
+  /* get the discont event and return */
+  gst_bytestream_get_status (ebml->bs, &remaining, &event);
+  if (!event || GST_EVENT_TYPE (event) != GST_EVENT_DISCONTINUOUS) {
+    gst_element_error (GST_ELEMENT (ebml),
+		       "No discontinuity event after seek");
+    if (event)
+      gst_event_unref (event);
+    return NULL;
+  }
+
+  return event;
 }
 
 /*
@@ -308,8 +363,9 @@ gboolean
 gst_ebml_read_skip (GstEbmlRead *ebml)
 {
   gint bytes;
-  guint32 id;
+  guint32 id, remaining;
   guint64 length;
+  GstEvent *event;
 
   if ((bytes = gst_ebml_read_element_id (ebml, &id, NULL)) < 0)
     return FALSE;
@@ -319,7 +375,23 @@ gst_ebml_read_skip (GstEbmlRead *ebml)
     return FALSE;
   gst_bytestream_flush_fast (ebml->bs, bytes);
 
-  return gst_bytestream_flush (ebml->bs, length);
+  /* do we have enough bytes left to skip? */
+  gst_bytestream_get_status (ebml->bs, &remaining, &event);
+  if (event) {
+    g_warning ("Unexpected event before skip");
+    gst_event_unref (event);
+  }
+
+  if (remaining >= length)
+    return gst_bytestream_flush (ebml->bs, length);
+
+  if (!(event = gst_ebml_read_seek (ebml,
+			gst_bytestream_tell (ebml->bs) + length)))
+    return FALSE;
+
+  gst_event_unref (event);
+
+  return TRUE;
 }
 
 /*
@@ -365,7 +437,8 @@ gst_ebml_read_uint (GstEbmlRead *ebml,
   size = GST_BUFFER_SIZE (buf);
   if (size < 1 || size > 8) {
     gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid integer element size %d", size);
+		       "Invalid integer element size %d at position %llu (0x%llu)",
+		       size, GST_BUFFER_OFFSET (buf), GST_BUFFER_OFFSET (buf));
     gst_buffer_unref (buf);
     return FALSE;
   }
@@ -400,7 +473,8 @@ gst_ebml_read_sint (GstEbmlRead *ebml,
   size = GST_BUFFER_SIZE (buf);
   if (size < 1 || size > 8) {
     gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid integer element size %d", size);
+		       "Invalid integer element size %d at position %llu (0x%llx)",
+		       size, GST_BUFFER_OFFSET (buf), GST_BUFFER_OFFSET (buf));
     gst_buffer_unref (buf);
     return FALSE;
   }
@@ -439,7 +513,8 @@ gst_ebml_read_float (GstEbmlRead *ebml,
 
   if (size != 4 && size != 8 && size != 10) {
     gst_element_error (GST_ELEMENT (ebml),
-		       "Invalid float element size %d", size);
+		       "Invalid float element size %d at position %llu (0x%llx)",
+		       size, GST_BUFFER_OFFSET (buf), GST_BUFFER_OFFSET (buf));
     gst_buffer_unref (buf);
     return FALSE;
   }