Bas Vermeulen wrote:
We've run into a problem with the gstreamer sbcdec plugin, where a
pipeline would accumulate memory at the rate of data sent into it. This
is caused by invalid data in a packet (incomplete or wrong data in the
stream), causing sbc_decode to return -2 (sbc_unpack_frame can't find
the SBC_SYNCWORD in data[0]).
The sbcdec plugin handles this by putting away the buffer, and trying
again when a new buffer comes in. Since the buffer isn't changed (only
new data tacked on), sbc_decode will continue to send the -2 response
from sbc_unpack_frame function, and the sbcdec plugin will continue to
accumulate data into the buffer it is working on.
The fix is to simply drop a buffer when sbc_decode returns -2.
I just realised this doesn't do enough, as sbc_decode can return
negative values in the range of -1 to -4 (-1 being need more data, the
rest being can't handle this frame for various reasons).
I've included a new version of the patch, which handles a -1 return
value by keeping the buffer for the next decode, and the other values by
dropping the buffer. This should also fix similar errors in case we get
a bad CRC or a faulty packet.
Regards,
Bas Vermeulen
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--- /usr/src/nokia/mms_p2430-mute/mms_p2430/src/plugins/audio/decoder/gstrtpsbc/src/gstsbcdec.c 2009-12-01 11:32:45.000000000 +0100
+++ gstsbcdec.c 2009-12-04 12:23:04.000000000 +0100
@@ -95,7 +95,18 @@
GST_BUFFER_DATA(output), codesize,
NULL);
if (consumed <= 0)
- break;
+ {
+ /*
+ * sbc_decode returns -1 when not enough data is available to process.
+ * If that is the case, we need to tack on another buffer.
+ * In case of other errors (crc failure, SBC_SYNCWORD not found, etc),
+ * keeping the offending data does no good, as we will keep getting the
+ * same error over and over. So just free the buffer by jumping to done.
+ */
+ if (-1 == consumed)
+ break;
+ goto done;
+ }
/* we will reuse the same caps object */
if (dec->outcaps == NULL) {
