Date: Tue, 06 Jul 2004 13:07:07 +0900 From: Alexander Nedotsukov <bland@FreeBSD.org> To: Hidetoshi Shimokawa <simokawa@sat.t.u-tokyo.ac.jp> Cc: freebsd-firewire@FreeBSD.org Subject: Re: Block noise? when trying to send dv stream to video camera Message-ID: <40EA256B.6060101@FreeBSD.org> In-Reply-To: <87d63bswig.wl@tora.nunu.org> References: <40E4C710.1040702@FreeBSD.org> <87d63bswig.wl@tora.nunu.org>
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Hidetoshi Shimokawa wrote: >How log does the noise-less image last? a few seconds or shorter? > > > >>square blocks and some parts of those blocks stay gray while >>another contains correct image. Blocks are moving. The size of blocks >>may vary. Time before video get corrupted as well from 0 to 50 sec. Do >>you have any idea what it can be and what is much better how to fix the >>situation? >>I running one week old -CURRENT world+kernel. >> >>Thanks, >>Alexander. >> >> > >Every DV frame has a timestamp on the packet. The DV specification >said that the timestamp must be synced with the bus cycle timer. >Some DV equipments are very sensitive to it and if it's out of sync, >we often observe block noises. > >Current iso transmit code start transmit at specific bus cycle to >ensure that the timestamp must be synced at the start. >The following packets have timestamps which are calculated under >the assumption that a packet is sent for each bus cycle. >If the assumption is broken for some reason(bus is busy to transmit >a packer, the host is too slow to feed the packet and etc.), >the timestamp will be out of sync. > >Do you use PAL or NTSC? > > Well now things become a little bit clear :-) Thanks for explanation. I use NTSC and regilar 4:3 video format. The time I can see noise-less image vary. Some time it 40-50 sec before noise come and some time I see it right after start fwcontrol -S. After you explained me this timing issues I tried to start fwcontrol from system console (not from gnome-terminal window as I did before) and yahoo block noise gone. But there is still a problem. Now Video plays nicely about 5-10 mins and stops then. I can see (EAGAIN) errors reported by fwcontrol utility and this on the system console: ... fwohci0: IT DMA underrun (0x3ab08011) fwohci0: IT DMA underrun (0x3ab08011) fwohci0: IT DMA underrun (0x3ab08011) fwohci0: IT DMA underrun (0x3ab08011) ... Few notes about system performance. I have PIII 1GHz machine here with UDMA66 disk. cpu is 100% idle all the time video transmitted to the camera. All the best, Alexander.
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