ac3_probe: fix probing of non standard AC3

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/ac3dec.c

@@ -37,18 +37,36 @@ static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id)
     end = buf + p->buf_size;
 
     for(; buf < end; buf++) {
-        if(buf > p->buf && (buf[0] != 0x0B || buf[1] != 0x77) )
+        if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)
+                        && !(buf[0] == 0x77 && buf[1] == 0x0B) )
             continue;
         buf2 = buf;
 
         for(frames = 0; buf2 < end; frames++) {
+            uint8_t buf3[4096];
+            int i;
             if(!memcmp(buf2, "\x1\x10\0\0\0\0\0\0", 8))
                 buf2+=16;
-            init_get_bits(&gbc, buf2, 54);
+            if (buf[0] == 0x77 && buf[1] == 0x0B) {
+                for(i=0; i<8; i+=2) {
+                    buf3[i  ] = buf[i+1];
+                    buf3[i+1] = buf[i  ];
+                }
+                init_get_bits(&gbc, buf3, 54);
+            }else
+                init_get_bits(&gbc, buf2, 54);
             if(avpriv_ac3_parse_header(&gbc, &hdr) < 0)
                 break;
-            if(buf2 + hdr.frame_size > end ||
-               av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, hdr.frame_size - 2))
+            if(buf2 + hdr.frame_size > end)
+                break;
+            if (buf[0] == 0x77 && buf[1] == 0x0B) {
+                av_assert0(hdr.frame_size <= sizeof(buf3));
+                for(; i<hdr.frame_size; i+=2) {
+                    buf3[i  ] = buf[i+1];
+                    buf3[i+1] = buf[i  ];
+                }
+            }
+            if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, gbc.buffer + 2, hdr.frame_size - 2))
                 break;
             if (hdr.bitstream_id > 10)
                 codec_id = AV_CODEC_ID_EAC3;