> 1. Again I'll mention Ronald Bultje's comment that if a card provides
> frames as V4L2_FIELD_INTERLACED, it should also be able to say
> top-field-first or bottom-field first.
IMHO the field order should simply specified in the specs (see also
Michaels comment).
> > struct v4l2_pix_format
> > {
> > #if 0
> > /* FIXME: specify ITU-R 601, ... here ??? */
> > __u32 colorspace;
> 2. Doing a general colourspace definition is dangerous, IMHO, so I
> like the idea of having a bunch of #defines, like with the video
> standard. It will make things easier. Having a way to detect the
> broken bt878 extents would kick! Comments on this as a start?
I'd make that a enum, not #defines, but its bascially the same.
> > struct timeval timestamp;
> > struct v4l2_timecode timecode;
> > __u32 sequence;
> > __u32 reserved[3];
> > };
>
> 3. You give one timestamp per buffer. It would be really awesome to
> get, for an interlaced buffer, the timestamp of each field, rather than
> being forced to use ALTERNATE.
Why?
> > struct v4l2_captureparm
> > {
> > __u32 capability; /* Supported modes */
> > __u32 capturemode; /* Current mode */
> > unsigned long timeperframe; /* Time per frame in .1us units */
> > __u32 extendedmode; /* Driver-specific extensions */
> > __u32 readbuffers; /* # of buffers for read */
> > __u32 reserved[4];
> > };
> > /* Flags for 'capability' and 'capturemode' fields */
> > #define V4L2_MODE_HIGHQUALITY 0x0001 /* High quality imaging mode */
> > #define V4L2_CAP_TIMEPERFRAME 0x1000 /* timeperframe field is supported */
>
> 4. I don't understand 'timeperframe'. We already have v4l2_standard,
> shouldn't it just be retrieved from that?
Hmm, bttv implements it this way ...
v4l2_video_std_construct(&s, bttv_tvnorms[btv->tvnorm].v4l2_id);
parm->parm.capture.timeperframe = v4l2_video_std_tpf(&s);
... which clearly indicates it is indeed redundant. At least for TV
cards, what about usb webcams?
> Also, it would be better to
> do the numerator/denominator thing here too, no?
Probably (unless we drop it anyway ...)
Gerd
--
You can't please everybody. And usually if you _try_ to please
everybody, the end result is one big mess.
-- Linus Torvalds, 2002-04-20
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