David Engel <[EMAIL PROTECTED]> writes:
>> *sigh*. So on average you lose the count of one frame ever 18 minutes...
>
> I know, but it's still a bug!
True, but it's much lesser of an evil than the current code. The
current code is nearly unusable watching LiveTV. But eh, I don't have
commit access.
>> Perhaps something like the attached patch? I think this will do the
>
> Yes, like that, but I think you need to allow for a 2-byte pad.
> bufptr is incremented before we access bufptr[1], so it's actually the
> second byte after the end of buffer check.
picky picky picky. Here's another version with some updated comments.
-derek
Index: libs/libmythtv/ivtvdecoder.cpp
===================================================================
RCS file: /var/lib/mythcvs/mythtv/libs/libmythtv/ivtvdecoder.cpp,v
retrieving revision 1.36
diff -u -r1.36 ivtvdecoder.cpp
--- libs/libmythtv/ivtvdecoder.cpp 29 Jan 2005 00:06:57 -0000 1.36
+++ libs/libmythtv/ivtvdecoder.cpp 16 Feb 2005 21:38:37 -0000
@@ -255,7 +255,9 @@
unsigned char *bufptr = buf + start;
unsigned int v = 0;
- while (bufptr < buf + len)
+ // Don't consume the last two bytes in the buffer; we need thos extra bytes
+ // to test the picture start type.
+ while (bufptr < buf + len - 2)
{
v = *bufptr++;
@@ -337,8 +339,10 @@
}
case PICTURE_START:
{
- //int type = (bufptr[1] >> 3) & 7;
- //if (type >= 1 && type <= 3)
+ // Make sure this is a real picture. Otherwise we could
+ // lose time sync and cause all sorts of WAF issues.
+ int type = (bufptr[1] >> 3) & 7;
+ if (type >= 1 && type <= 3)
{
framesScanned++;
if (exitafterdecoded)
@@ -450,15 +454,17 @@
}
else
{
- vidscan = vidread;
- if (vidread - vidwrite > 3)
+ // MpegPreProcessPkt checks up to (but not including) the last two bytes
+ // so let's not lose those last bytes when we shift the buffer.
+ vidscan = vidread - 2;
+ if (vidscan - vidwrite > 3)
{
- vid2write = vidread - 3 - vidwrite;
+ vid2write = vidscan - 3 - vidwrite;
videndofframe = 0;
}
else
{
- vid2write = vidread - vidwrite;
+ vid2write = vidscan - vidwrite;
videndofframe = 1;
}
}
--
Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
Member, MIT Student Information Processing Board (SIPB)
URL: http://web.mit.edu/warlord/ PP-ASEL-IA N1NWH
[EMAIL PROTECTED] PGP key available
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