SDI API - Revision history

J-b at 14:34, 1 October 2013

2013-10-01T14:34:49Z

← Older revision		Revision as of 14:34, 1 October 2013
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	Receive minimum of one line of data starting at EAV to subsequent EAV. Either in v210 for 10-bit or UYVY for 8-bit. Userspace has the responsibility of parsing the datastream (easily doable with a libsdi component).		Receive minimum of one line of data starting at EAV to subsequent EAV. Either in v210 for 10-bit or UYVY for 8-bit. Userspace has the responsibility of parsing the datastream (easily doable with a libsdi component).

			[[Category:Dev Discussions]]

Kieran at 08:29, 1 October 2013

2013-10-01T08:29:13Z

← Older revision		Revision as of 08:29, 1 October 2013
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	== Thoughts about SDI API ==		== Thoughts about SDI API ==

	There are a number of manufacturers using V4L2, sometimes alongside ALSA, to provide Linux drivers for their SDI cards. This causes a lot of issues for professional users. There are a number of proprietary APIs that provide a better interface for professional users. On the capture side ~~they~~ can be described as follows:		There are a number of manufacturers using V4L2, sometimes alongside ALSA, to provide Linux drivers for their SDI cards. This causes a lot of issues for professional users. There are a number of proprietary APIs that provide a better interface for professional users. On the capture side the issues can be described as follows:

	* Separate file descriptors for Audio/Video meaning sync must be performed with timestamps (if they exist; sometimes they don't). This is the most serious issue in a professional environment.		* Separate file descriptors for Audio/Video meaning sync must be performed with timestamps (if they exist; sometimes they don't). This is the most serious issue in a professional environment.

Kieran: /* SDI extension to V4L2 thoughts */

2013-10-01T07:10:13Z

SDI extension to V4L2 thoughts

← Older revision		Revision as of 07:10, 1 October 2013
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	== SDI extension to V4L2 thoughts ==		== SDI extension to V4L2 thoughts ==
	Single SDI file descriptor. Open, setup options (bit-depth etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).		Single SDI file descriptor. Open, setup options (bit-depth etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).

			Receive minimum of one line of data starting at EAV to subsequent EAV. Either in v210 for 10-bit or UYVY for 8-bit. Userspace has the responsibility of parsing the datastream (easily doable with a libsdi component).

Kieran: /* SDI extension to V4L2 */

2013-09-26T19:28:15Z

SDI extension to V4L2

← Older revision		Revision as of 19:28, 26 September 2013
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	Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.		Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.

	== SDI extension to V4L2 ==		== SDI extension to V4L2 thoughts ==
	Single SDI file descriptor. Open, setup options (bit-depth etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).		Single SDI file descriptor. Open, setup options (bit-depth etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).

Kieran at 19:27, 26 September 2013

2013-09-26T19:27:44Z

← Older revision		Revision as of 19:27, 26 September 2013
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	* Impossible to select number of lines to capture per poll response (e.g x lines, one field, one frame)		* Impossible to select number of lines to capture per poll response (e.g x lines, one field, one frame)
	* Impossible to keep NTSC audio samples per video frame cadence, nor line number where audio starts		* Impossible to keep NTSC audio samples per video frame cadence, nor line number where audio starts
	* 10-bit capture (though this is easy to solve in V4L2)		* 8 or 10-bit capture (though this is easy to solve in V4L2)
	* Signals when frames are dropped (so alternative signals can be sent)		* Signals when frames are dropped (so alternative signals can be sent)
	* An API for accessing VBI and HBI in 10-bit alongside the frame for things like Closed captions		* An API for accessing VBI and HBI in 10-bit alongside the frame for things like Closed captions
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	Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.		Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.

	== ~~API thoughts~~ ==		== SDI extension to V4L2 ==
	Single file descriptor. Open, setup options (~~pixel format~~ etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).		Single SDI file descriptor. Open, setup options (bit-depth etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).

Kieran at 19:16, 26 September 2013

2013-09-26T19:16:39Z

← Older revision		Revision as of 19:16, 26 September 2013
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	== API thoughts ==		== API thoughts ==
	Single file descriptor. Open, setup options (pixel format etc), poll on descriptor with ~~queued and dqueued mmapped~~ buffers.		Single file descriptor. Open, setup options (pixel format etc), poll on descriptor with buffers to read (or mmap if the data is large enough?).

Kieran at 19:13, 26 September 2013

2013-09-26T19:13:38Z

← Older revision		Revision as of 19:13, 26 September 2013
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	* 10-bit capture (though this is easy to solve in V4L2)		* 10-bit capture (though this is easy to solve in V4L2)
	* Signals when frames are dropped (so alternative signals can be sent)		* Signals when frames are dropped (so alternative signals can be sent)
	* An API for accessing VBI and HBI in 10-bit alongside the frame		* An API for accessing VBI and HBI in 10-bit alongside the frame for things like Closed captions
	* An API to access ancillary data in a proper way (e.g. ClosedCaption)

	Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.		Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.

Lu zero at 19:10, 26 September 2013

2013-09-26T19:10:50Z

← Older revision		Revision as of 19:10, 26 September 2013
Line 10:		Line 10:
	* Signals when frames are dropped (so alternative signals can be sent)		* Signals when frames are dropped (so alternative signals can be sent)
	* An API for accessing VBI and HBI in 10-bit alongside the frame		* An API for accessing VBI and HBI in 10-bit alongside the frame
			* An API to access ancillary data in a proper way (e.g. ClosedCaption)

	Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.		Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.

Kieran: /* Thoughts about SDI API */

2013-09-26T19:04:08Z

Thoughts about SDI API

← Older revision		Revision as of 19:04, 26 September 2013
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	* Separate file descriptors for Audio/Video meaning sync must be performed with timestamps (if they exist; sometimes they don't). This is the most serious issue in a professional environment.		* Separate file descriptors for Audio/Video meaning sync must be performed with timestamps (if they exist; sometimes they don't). This is the most serious issue in a professional environment.
	* Timestamps are sometimes generated with the system clock and do not reflect the way audio is transported in SDI, nor precise nature of NTSC timestamps.		* Timestamps are sometimes generated with the system clock and do not reflect the way audio is transported in SDI, nor precise nature of NTSC timestamps.
	* Impossible to select number of lines to capture per poll (e.g x lines, one field, one frame)		* Impossible to select number of lines to capture per poll response (e.g x lines, one field, one frame)
	* Impossible to keep NTSC audio samples per video frame cadence, nor line number where audio starts		* Impossible to keep NTSC audio samples per video frame cadence, nor line number where audio starts
	* 10-bit capture (though this is easy to solve in V4L2)		* 10-bit capture (though this is easy to solve in V4L2)

Kieran at 19:01, 26 September 2013

2013-09-26T19:01:14Z

← Older revision		Revision as of 19:01, 26 September 2013
Line 12:		Line 12:

	Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.		Most of these issues are caused by the separation of Audio/Video/Blanking so the two solutions in that area could be accurate timestamps (using a 27mhz clock) or data returned multiplexed. Another way of solving the issue would be to have an SDI "pixel format" and userspace could parse the datastream itself as VLC does with the Computermodules SD-SDI driver.

			== API thoughts ==
			Single file descriptor. Open, setup options (pixel format etc), poll on descriptor with queued and dqueued mmapped buffers.