> Any comments?
No, other than what has been discussed on irc:
- Add a new V4L2_CAP_VIDEO_M2M capability instead of ORing CAPTURE and
OUTPUT.
- Don't add aliases, just document better if needed.
- The spec has to change so that M2M devices do not need buffers to be
queued before calling STREAMON. It's an exception to the rule.
I hope I got this right, it's from memory :-)
Regards,
Hans
>
> On Tue, Sep 14, 2010 at 11:29 PM, Kamil Debski <k.debski@xxxxxxxxxxx>
> wrote:
>> Hello,
>>
>> Mem2mem devices currently use V4L2_CAP_VIDEO_CAPTURE and
>> V4L2_CAP_VIDEO_OUTPUT capabilities. One might expect that a capture
>> device is a camera and an output device can display images. If I
>> remember correct our discussion during the Helsinki v4l2 summit, Hans de
>> Goede has pointed that such devices are listed in applications and can
>> confuse users. The user expects a camera and he has to choose from a
>> long list of devices.
>>
>> The solution to this would be the introduction of two new capability
>> V4L2_CAP_VIDEO_M2M. Such devices would not be listed when user is
>> expected to choose which webcam or TV tuner device to use.
>>
>> Another thing about m2m devices is the naming of buffers:
>> V4L2_BUF_TYPE_VIDEO_CAPTURE means the destination buffer and
>> V4L2_BUF_TYPE_VIDEO_OUTPUT means source. This indeed is confusing, so I
>> think the introduction of two new buffer types is justified. I would
>> recommend V4L2_BUF_TYPE_M2M_SOURCE and V4L2_BUF_TYPE_M2M_DESTINATION to
>> clearly state what is the buffer's purpose.
>>
>> I would be grateful for your comments to this RFC.
>>
>> Best wishes,
>> --
>> Kamil Debski
>> Linux Platform Group
>> Samsung Poland R&D Center
>>
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--
Hans Verkuil - video4linux developer - sponsored by TANDBERG, part of Cisco
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