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From: Andy Walls <awalls@md.metrocast.net>
To: Hans Verkuil <hverkuil@xs4all.nl>,
	Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Tomasz Stanislawski <t.stanislaws@samsung.com>,
	linux-media@vger.kernel.org, m.szyprowski@samsung.com,
	kyungmin.park@samsung.com, laurent.pinchart@ideasonboard.com
Subject: Re: [RFC] DV timings spec fixes at V4L2 API - was: [PATCH 1/8] v4l: add macro for 1080p59_54 preset
Date: Tue, 05 Jul 2011 15:02:36 -0400	[thread overview]
Message-ID: <b1f62aa0-bcc1-497f-843f-7c4473f75f73@email.android.com> (raw)
In-Reply-To: <201107051520.17361.hverkuil@xs4all.nl>

Hans Verkuil <hverkuil@xs4all.nl> wrote:
>I can work on the proposal this week for that. The only reason the fps
>hasn't been added
>yet is that I never had the time to do the research on how to represent
>the fps reliably
>for all CEA/VESA formats. Hmm, pixelclock / total_framesize should
>always work, of course.
>
>We can add a flags field as well (for interlaced vs progressive and
>perhaps others such as
>normal vs reduced blanking).
>
>That leaves the problem with GTF/CVT. I'll get back to that tomorrow. I
>have ideas, but
>I need to discuss it first.
>
>Regards,
>
>	Hans
>--
>To unsubscribe from this list: send the line "unsubscribe linux-media"
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>the body of a message to majordomo@vger.kernel.org
>More majordomo info at  http://vger.kernel.org/majordomo-info.html

For fps you could use horizontal_line_freq/lines_per_frame.

However, all of the non-integer fps numbers I have seen in this email chain all seem to be multiples of 29.97002997 Hz. So maybe you could just use the closest integer rate with a flag labeled "ntsc_bw_timing_hack" to indicate the fractional rates. :) 

That 29.97 Hz number comes from the NTSC decision in 1953(!) to change the horizontal line freq to 4.5 MHz/286.  Note that

(4.5 MHz/286)/525 = 30 * (1000/1001) = 29.97002997 Hz

It is interesting to see one of the most ingenious analog hacks in TV history (to achieve color and B&W backward compatabilty while staying in the 10% tolerance of the old B&W receivers) being codified in digital standards over 50 years later. It boggles the mind...

Regards,
Andy

  reply	other threads:[~2011-07-05 19:02 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-29 12:51 [PATCH v6 0/8] TV drivers for Samsung S5P platform (media part) Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 1/8] v4l: add macro for 1080p59_54 preset Tomasz Stanislawski
2011-07-04 16:09   ` [RFC] DV timings spec fixes at V4L2 API - was: " Mauro Carvalho Chehab
2011-07-04 22:47     ` Laurent Pinchart
2011-07-04 23:28       ` Mauro Carvalho Chehab
2011-07-05  6:46       ` Hans Verkuil
2011-07-05  7:26     ` Hans Verkuil
2011-07-05 12:08       ` Mauro Carvalho Chehab
2011-07-05 13:20         ` Hans Verkuil
2011-07-05 19:02           ` Andy Walls [this message]
2011-07-05 23:25             ` Mauro Carvalho Chehab
2011-07-06  1:05               ` Andy Walls
2011-07-06 11:04           ` Mauro Carvalho Chehab
2011-07-06 11:31             ` Hans Verkuil
2011-07-06 11:48               ` Mauro Carvalho Chehab
2011-07-06 12:03                 ` Laurent Pinchart
2011-07-06 12:09                   ` Mauro Carvalho Chehab
2011-07-06 12:13                     ` Laurent Pinchart
2011-07-06 12:20                       ` Mauro Carvalho Chehab
2011-07-06 12:14                 ` Hans Verkuil
2011-07-06 12:31                   ` Mauro Carvalho Chehab
2011-07-06 12:56                     ` Hans Verkuil
2011-07-06 14:10                       ` Mauro Carvalho Chehab
2011-07-06 19:39                   ` Mauro Carvalho Chehab
2011-07-07 11:33                     ` Hans Verkuil
2011-07-07 13:52                       ` Mauro Carvalho Chehab
2011-07-07 14:58                         ` Hans Verkuil
2011-07-07 16:18                           ` Mauro Carvalho Chehab
2011-07-07 17:52                         ` Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 2/8] v4l: add g_tvnorms_output callback to V4L2 subdev Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 3/8] v4l: add g_dv_preset " Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 4/8] v4l: add g_std_output " Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 5/8] v4l: fix v4l_fill_dv_preset_info function Tomasz Stanislawski
2011-07-14 16:02   ` Mauro Carvalho Chehab
2011-06-29 12:51 ` [PATCH 6/8] v4l: s5p-tv: add drivers for HDMI on Samsung S5P platform Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 7/8] v4l: s5p-tv: add SDO driver for " Tomasz Stanislawski
2011-06-29 12:51 ` [PATCH 8/8] v4l: s5p-tv: add TV Mixer " Tomasz Stanislawski

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