V4L for DVB ASI
Hello,
We are DVB ASI PCI/PCIe card manufacturers in Canada. Some of you may have heard about our distributors: DVEO/Computer Modules. We encourage open source and use open source to develop our Linux products. I have been doing some research on getting our already open sourced DVB ASI drivers to work with either v4l or the regular DVB API.
I had asked a question to the community a while ago and have had few responses. The question was mainly to find out if there is any interest in the community towards this goal. We will be happy to work with you. The initial response was to work on v4l as opposed to the DVB API. Since the cards support PID filtering and other transport stream analysis, I am encouraged to use DVB API instead of V4L because of TS feature support at the software level. But then I could be wrong since I have not done a lot of research on these two APIs. Sigmund Augdal had listed out the pros and cons to my previous question:
Use the DVB Api:
pros:
* you can take advantage of the software pid and section filters in the dvb framework
* if your device supports hardware pid/section filters, apis will be available to take advantage of them
* userspace applications that handle mpeg2 ts often use this api, and would be easy to adapt.
cons:
* you might need to extend the apis to handle asi cards
Use the v4l2 api:
pros:
* semantics are well defined.
* provides an extensible api using so called "controls" cons:
* adapting user space applications will be more difficult
* no reuse of software filters
If Anybody wants to look at the drivers, they are available at http://www.linsys.ca in customer support section.
Thanks for any advice and help.
Kind Regards,
Dinesh
Signature · 17 lines
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Hi Dinesh,
Quoted 39 lines · On Thursday 24 July 2008 18:36:27 Dinesh Bhat wrote:
Hello,
We are DVB ASI PCI/PCIe card manufacturers in Canada. Some of you may have heard about our distributors: DVEO/Computer Modules. We encourage open source and use open source to develop our Linux products. I have been doing some research on getting our already open sourced DVB ASI drivers to work with either v4l or the regular DVB API.
I had asked a question to the community a while ago and have had few responses. The question was mainly to find out if there is any interest in the community towards this goal. We will be happy to work with you. The initial response was to work on v4l as opposed to the DVB API. Since the cards support PID filtering and other transport stream analysis, I am encouraged to use DVB API instead of V4L because of TS feature support at the software level. But then I could be wrong since I have not done a lot of research on these two APIs. Sigmund Augdal had listed out the pros and cons to my previous question:
Use the DVB Api:
pros:
* you can take advantage of the software pid and section filters in
the dvb framework
* if your device supports hardware pid/section filters, apis will be
available to take advantage of them
* userspace applications that handle mpeg2 ts often use this api,
and would be easy to adapt.
cons:
* you might need to extend the apis to handle asi cardsUse the v4l2 api:
pros:
* semantics are well defined.
* provides an extensible api using so called "controls"
cons:
* adapting user space applications will be more difficult
* no reuse of software filters
Quoted 2 lines
If Anybody wants to look at the drivers, they are available at
http://www.linsys.ca in customer support section.
Since I am heavily involved in the MPEG support for V4L2 I suspect that I am probably the right person to look into this. I must have missed this the first time you mailed it, probably because the subject didn't mention V4L. I am not involved in the DVB API, with the exception of the MPEG decoding part of it (dvb/video.h, dvb/audio.h) since my ivtv driver uses that for the MPEG decoding.
Looking over the functionality of ASI I see (correct me if I am wrong) that it is basically a transport standard for MPEG-TS streams as used in DVB applications. There is no routing, tuning or (de)modulating involved. The device is fed one or more MPEG-TS streams, they are muxed and timestamped and sent out over the ASI connection. And it can also receive an MPEG-TS stream and is able to demux that depending on the PIDs.
In my personal opinion I would say that this falls under the V4L API (with perhaps some use of the video.h/audio.h interfaces from DVB). Regardings the cons that are mentioned: since there is no standard for the ASI API all user space apps need to be converted anyway if a standard would appear. And as I understand it, any filtering is done in hardware.
Looking at the ioctls of your driver I would say that most if not all of these can be implemented as controls. Based on the admittedly limited information I have I see no obstacle of getting this into the v4l framework.
Regards,
Hans
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