The crash is somewhere in the libdca library that decodes DTS streams. I'm looking at whether I can early out there if a bad bitstream is found. An attempt at checking the max bound of the read wasn't enough to fix that sample crashing it. This is a bug in libdca and should be filed there.

So instead I added a typefind for DEGAS images so your file won't be misdetected as DTS anymore (but it'll still crash if given to dtsdec till libdca is fixed).

Created attachment 178767 [details] [review]
typefind: add typefind for DEGAS images

This fixes at least one DEGAS image from being misdetected as DTS audio
(see https://bugzilla.gnome.org/show_bug.cgi?id=625129).

Looks good but better use POSSIBLE instead of LIKELY here, at least for the compressed case

Created attachment 178823 [details] [review]
add typefind for DEGAS images

Use POSSIBLE + 5 instead of likely, and use a single media type for all of the types.

Comment on attachment 178823 [details] [review]
add typefind for DEGAS images

>+  len = gst_type_find_get_length (tf);
>+  if (len < 4)
>+    return;
>+  data = gst_type_find_peek (tf, 0, 4);

Since there's supposed to be a 34-byte header, we may just as well check for that (not that it matters).

>+  resolution = GST_READ_UINT16_BE (data);
>+  if (len == 32034) {
>+    /* could be DEGAS */
>+    if (resolution <= 2)

Isn't resolution a bitfield? (meaning shouldn't it be <= 3?)

>+      gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
>+          "image/x-degas", NULL);
>+  } else if (len == 32066) {
>+    /* could be DEGAS Elite */
>+    if (resolution <= 2)
>+      data = gst_type_find_peek (tf, len - 16, 8);
>+    for (n = 0; n < 4; n++) {
>+      if (GST_READ_UINT16_BE (data + n * 2) > 2)
>+        return;
>+      gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
>+          "image/x-degas", NULL);
>+    }

Not sure I understand the nesting here.

Shouldn't we bail out (return) if resolution is > 3? (see above re. bitfield)

Or, put differently: shouldn't the data= bit and the whole loop etc. all be in a

  if (resolution <=3) {
    ...
  }

block?

Next, shouldn't the gst_type_find_suggest_simple() be outside the for loop? Otherwise we suggest after the first value already, and not only if all 4 values are ok.


>+  } else if (len >= 66 && len < 32066) {
>+    /* could be compressed DEGAS Elite, but it's compressed and so we can't rely on size,
>+       it does have 4 16 bytes values near the end that are 0-2 though. */
>+    if ((resolution & 0x8000) && (resolution & 0x7fff) <= 2)
>+      data = gst_type_find_peek (tf, len - 16, 8);
>+    for (n = 0; n < 4; n++) {
>+      if (GST_READ_UINT16_BE (data + n * 2) > 2)
>+        return;
>+      gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
>+          "image/x-degas", NULL);
>+    }
>+  }

Same questions here re. nesting.

>+}
>+

> Since there's supposed to be a 34-byte header, we may just as well check for
> that (not that it matters).

Why not. Done.

> Isn't resolution a bitfield? (meaning shouldn't it be <= 3?)

I think it is not. Rereading the desription, it is indeed not very clear, but the following paragraph seems clear enough to quash the uncertainty (look at the example values given):

1 word          resolution (same as Degas, but high order bit is set;
                i.e., hex 8000 = low res, hex 8001 = medium res,
                hex 8002 = high res).  Other bits may be used in the
                future; use a simple bit test rather than checking
                for specific word values.

> Not sure I understand the nesting here.

"oops". Yes, bad nesting. The other too, it was copy/paste/adapt.

Created attachment 179276 [details] [review]
typefind: add typefind for DEGAS images

This fixes at least one DEGAS image from being misdetected as DTS audio
(see https://bugzilla.gnome.org/show_bug.cgi?id=625129).

Thanks!

 commit 2acdbdabaa3736ba66b1170e070b3a1bde37f35a
 Author: Vincent Penquerc'h <vincent.penquerch@collabora.co.uk>
 Date:   Tue Jan 25 13:39:25 2011 +0000

    typefind: add typefinder for DEGAS images
    
    This fixes at least one DEGAS image from being misdetected as DTS audio.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=625129

(The reason I thought it was a bitfield is some other website than the one you referenced, since that one was down yesterday. Your version/quote makes more sense though)