> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Martin Dauskardt > Sent: 12 June 2006 07:50 > To: [email protected] > Subject: Re: [ivtv-devel] IVTV_IOC_STOP_DECODE vs. IVTV_IOCTL_FWAPI > > > On Wednesday 07 June 2006 09:03, Martin Dauskardt wrote: > > > > From: Hans Verkuil <[EMAIL PROTECTED]> > > > > > > > > > But why is there such a long delay with the recommended ioctl? > > > > > What makes the difference? How can I improve it? > > > > > > > > No idea. Try to set from debug messages in > > > > ivtv_stop_v4l2_decode_stream() to see what part takes > so much time. > > > > > > Hi Hans, > > > could you describe this a little more? Which debug level do you > > > recommend for this? > > > > No, I mean just add printk() messages at several places in > the function. > > You can see the timestamps of when the message was logged in > > (usually) /var/log/messages. So if you see a sizeable gap in > > timestamps between two printk's, then the code in between > must be the culprit. > > It's old-fashioned, but it works. > > I am still not sure in which area I should set the printk`s. > With debug level 21 set I now have the impression that it is > not the stop decode area, but the start decode area. That`s > strange, because starting the decoder works with the same > ioctl commands very fast, if the decoder is _stopped_ before > with a fwapi call. > > The log shows a lag of 5 seconds between IVTV_IOC_PLAY and > "Starting v4l2_decode". Hans, do you have any idea what is > happening here ?
I haven't looked at the logs yet but the decode process is roughly along the lines of The app calls write. This data is queued. When there is enough data the write thread starts and if necessary starts the decoder. So the problem here is more likely to be with the reading side not generating the data quickly and hence the delay before "starting 44l2_decode" being printed. I suspect what you are seeing there is a symptom of the problem rather than the source of the problem. John _______________________________________________ ivtv-devel mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-devel
