Streaming live video.

[Daniel K. <dan...@st...>]

Hi!

As stated in my previous message, I can display live video streams
on-screen using linux1394 and libdv. I'm not too happy about the
implementation though. What's bothering me most is the internal buffering
of iso data in the subsystem. I'd like to drop intermittent frames if my
processing is too slow. However with a naive approach I get the whole
backlog of frames in the buffer (and a klogd screaming badly about
dropping packets). My current workaround is to start/stop iso rcv for
every frame (which makes me yearn for the patch below to be applied
soon...). An alternative approach would be to spawn a seperate thread that
calls raw1394_loop_iterate in a tight loop, and telling the iso handler
just to drop packets when processing is too slow. Both suck. mmapping
/dev/ohci1394 is the proper way to go for OHCI, I think but that's not
really a generic solution. Has anyone thought about this already? Maybe a
'drop' option to start_iso_rcv() (which questionable semantics)?

Daniel.

Index: ohci1394.c
===================================================================
RCS file: /cvsroot/linux1394/ieee1394/ohci1394.c,v
retrieving revision 1.31
diff -u -r1.31 ohci1394.c
--- ohci1394.c  2000/05/19 16:13:54     1.31
+++ ohci1394.c  2000/06/02 22:42:16
@@ -1420,7 +1420,7 @@
 #endif
 
                 if (!test_and_set_bit(arg, &ohci->IR_channel_usage)) {
-                        PRINT(KERN_INFO, ohci->id,
+                        DBGMSG(KERN_INFO, ohci->id,
                               "listening enabled on channel %d", arg);
 
                         if (arg > 31) {
@@ -1446,7 +1446,7 @@
                 spin_lock_irqsave(&ohci->IR_channel_lock, flags);
 
                 if (test_and_clear_bit(arg, &ohci->IR_channel_usage)) {
-                        PRINT(KERN_INFO, ohci->id,
+                        DBGMSG(KERN_INFO, ohci->id,
                               "listening disabled on iso channel %d",
arg);
 
                         if (arg > 31) {


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