[xiph-cvs] cvs commit: snatch FAQ snatch.pl

Monty xiphmont at xiph.org
Sun Nov 11 14:43:29 PST 2001



xiphmont    01/11/11 14:43:29

  Modified:    .        snatch.pl
  Added:       .        FAQ
  Log:
  stupid robot bug ('stop' sent wrong code)

Revision  Changes    Path
1.29      +3 -2      snatch/snatch.pl

Index: snatch.pl
===================================================================
RCS file: /usr/local/cvsroot/snatch/snatch.pl,v
retrieving revision 1.28
retrieving revision 1.29
diff -u -r1.28 -r1.29
--- snatch.pl	2001/11/11 22:27:03	1.28
+++ snatch.pl	2001/11/11 22:43:28	1.29
@@ -556,7 +556,7 @@
 sub Robot_Stop{
     $last_timer_event=time();
     my $stopcode=join "",("Ks",pack ("S",4));
-    syswrite COMM_SOCK,$playcode;
+    syswrite COMM_SOCK,$stopcode;
 }
 
 sub Robot_Exit{
@@ -675,11 +675,12 @@
         my$now=time();
 
         if($TIMER_ENDTIMES[$#TIMER]<$now){
+	    Robot_Stop();
             Robot_Inactive();
         }else{
             
             if($now>=$next_timer_event){
-		SetupTimerDispatch() ;
+		SetupTimerDispatch();
             }else{
                 my$waiting_seconds=$next_timer_event-$now;
                 

1.1                  snatch/FAQ

Index: FAQ
===================================================================
Q: Does Snatch make perfect copies or grab the actual Real stream?

a: No.

Q: Does Snatch just take lots of fast screen captures?

A: No.  Snatch watches events going to and from the X server and
captures the appropriate video frames off the wire.  It will not grab
at the wrong rate, hose the machine/X server or 'capture' frames that
aren't actually displayed.

Q: Can I capture with the RealPlayer window hidden or iconified?

A: Yes.

Q: When I selecting silent video playback, the RealPlayer window
mostly stops responding and fills with garbage.  Can I fix this?

A: No, it's intentional. 'Silent video' stops all X updates from going
to the RealPlayer window; it's meant to squeeze any extra performance
possible from a machine with slow graphics hardware or slow processor
or both.  Remember that Snatch doesn't capture the Real stream, it
captures the video RealPlayer sends to the display.  Any dropped
frames due to poor machine performace will show up in the output as
jerkiness.

Although the video requires cycles to display, RealPlayer is also
spewing lots of updates to the interface during playback (like the
time display, scrolling info, etc).  For best performace, *everything*
gets turned off.  In this mode, all interaction with RealPlayer should
be made through the Snatch Robot.  Turning off silent video will bring
the RealPlayer window back to life.

Q: I begin playing/recording with audio playback set to silent, but
changing the setting later has no effect until I start a new stream!  Why?

A: Snatch doesn't currently try to set up the soundacard for playback
after a stream starts because it originally faked successful returns
to various sound API ioctl()s that might have failed (requiring
RealPlayer to try an alternate setup) if actually submitted to the
kernel.  Trying to emulate given settings with on the fly resampling
is rather complex given the failry innocuous nature of this 'bug', and
not bothering to fake through it correctly would just crash
RealPlayer or garble the output.

Q: I'm watching/recording video and switching between audio playback
and silent playback. When I turn off silent record, the audio I hear
is out of sync!  What gives?

A: Right now, Snatch tracks audio sync only for the output file.  It
doesn't try to re-sync the sound card if you reenable audio playback
during operation.  The captured file *will be fine*.  I didn't go
through the extra trouble mainly because on-the-fly resync would
require extra memory, buffering, and I didn't know if anyone cared
that much.

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