Re: [libdv-dev] Re: Should dv1394 work on PPC?

[Bill F. <bil...@mi...>]

On Wed, 19 Jun 2002, Daniel Kobras wrote:

> On Wed, Jun 19, 2002 at 10:43:19AM -0400, Bill Fink wrote:
> > On Wed, 19 Jun 2002, Stefan Lucke wrote:
> > > NO, thouse IDs come from X11. 
> > > #define FOURCC_YUY2 0x32595559
> 
> (Which is actually the hexdump of 'YUY2' [or '2YUY' depending on your
> preferred endianness].) 

Thanks for that little tidbit.

> > OK.  I'm not sure I totally understand all this.  xvinfo on XF 4.2 on
> > ATI (both DRI and non-DRI) and NVIDIA all report "id: 0x32595559 (2YUY)"
> > as the first available image format.  Without the patch, only the ATI
> > DRI case has wrong colors.  The XF CVS patch may address the ATI DMA/DRI
> > issue, but what about the NVIDIA case.  Does this mean the NVIDIA X driver
> > is currently broken (reporting incorrect image format)?
> 
> The more I look into this, it seems that Xv implementations are flawed.
> XvImageFormatValues contains an entry byte_order that should tell us
> about the endianness the card wants to see.  However, on the TiBook (ATI
> Rage Mobility M3) at least, this field is set to LSBFirst, where
> evidence clearly shows that it had better be MSBFirst.  Which tells us
> two things:  1) We cannot determine the correct byte order at compile
> time.  2) The sane way to automatically probe the correct byte order at
> runtime is flawed at least with some cards.  Conclusion: We're screwed.
> Easy way out:  Let the user override default byte order with a runtime
> switch.  Comments?

Yes, I believe a runtime option is the best workaround since I don't know
of any reliable method of distinguishing between the different cases.

> Below a little debugging patch to play with.  It assumes the default in
> current CVS, i.e. LSBFirst for little-endian systems, and MSBFirst on
> big-endian machines, tests against the byte order reported by XV, and
> bails out if they don't match.

I get the following on my home dual 500 MHz G4 with an ATI Rage128
graphics card (either with or without DRI enabled):

% playdv --no-mmap /dev/ieee1394/dv/host0/NTSC/in
format 4:3
Audio is 32.0 kHz, 12 bits quantization, 2 channels, emphasis off
Xv: ATI Rage128 Video Overlay: ports 59 - 59
Xv: ATI Rage128 Video Overlay: Unsupported endianness for format 0x32595559: LSBFirst
Xv: ATI Rage128 Video Overlay: format 0x32595559 is NOT in format list ( 0x32595559[YUY2] 0x59565955[UYVY] 0x32315659[YV12] 0x30323449[I420] )
Xv: (ERROR) could not grab any port!
playdv was compiled without SDL support
Attempt to use gtk for display failed
 Unable to establish a display method

The above was with DRI enabled.  The only difference in the output with
no DRI is the Xv ports are "55 - 55" instead of "59 - 59".  I can't easily
test my work system at the moment with the NVIDIA GeForce2 MX graphics
card, but I suspect it would yield the same results since the xvinfo is
the same for id 0x32595559 (2YUY).

						-Thanks

						-Bill