From owner-freebsd-firewire  Sun Feb 16 17:53: 4 2003
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Date: Mon, 17 Feb 2003 01:53:19 GMT
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From: Richard Tobin <richard@cogsci.ed.ac.uk>
Subject: Re: PAL DV, doesn't quite work
To: freebsd-firewire@freebsd.org
In-Reply-To: Richard Tobin's message of Sun, 16 Feb 2003 18:56:09 GMT
Organization: just say no
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I wrote:

> I then used "fwcontrol -R" to capture some video.  I used "playdv" to
> look at it, and both audio and video were scrambled.  I added a printf
> to fwdv.c, and found that the test
> 
>   pal = ((dv->payload[0] & DV_DSF_12) != 0);
> 
> was returning 0 because dv->payload[0] is 63 (DV_DSF_12 is 128).

I looked into this.  It seems that my PAL camcorder is falsely
claiming to be NTSC (525/60, 10 DIF sequences) in the header section,
and correctly claiming to be PAL (625/50, 12 DIF sequences) in the
VAUX section.

I looked at the dvlib code, and this seems to be a known problem; there
is a comment in dv_parse_header in parse.c:

  /* 
   * parse vaux data now to check if there is a inconsistanciy between
   * header->dsf and vaux data for auto mode
   */

and it treats the stream as 625/50 if either the DSF bit is set or
the VAUX data has the 50/60 flag set.

-- Richard

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