Hi Laurent,
On Thu, 2011-02-17 at 08:03 -0800, Laurent Pinchart wrote:
> Hi Stephan,
>
> On Friday 28 January 2011 20:35:05 Stephan Lachowsky wrote:
> > Parse the UVC 1.0 and UVC 1.1 VS_FORMAT_MPEG2TS descriptors.
> > This a stream based format, so we generate a dummy frame descriptor
> > with a dummy frame interval range.
>
> Thanks for the patch, and sorry for the late reply.
>
No worries, just glad to have the moss knocked off the stone.
> Don't you also need to implement support for the V4L2 MPEG CIDs ? I would
> expect the driver to support at least the controls used to select the MPEG
> format (MPEG2, TS), even if they're hardcoded to MPEG2-TS.
That would be possible, for the stream type there is your choice of
MPEG2-TS so that is trivial. There are a very limited set of
standardized controls that can be mapped: wKeyFrameRate, wPFrameRate,
wCompQuality from the VS probe/commit (GOP size, B frames, bitrate).
Since these controls are optional in the spec, and an overly simplistic
projection of the encoder's actual configuration space, device
manufactures (typically) choose instead to use custom XUs that expose
richer more representative ones.
Given this state of affairs, I think it would be prudent to blindly
forward the data stream (Which is all, in essence, this patch enables)
leaving the configuration to userspace.
I'm not suggesting we preclude adding XU -> MPEG2 CID mappings into
uvcvideo later, just that as is this is a valuable step forward.
Stephan
> > ---
> > drivers/media/video/uvc/uvc_driver.c | 41
> > ++++++++++++++++++++++++++++++++++ drivers/media/video/uvc/uvcvideo.h |
> > 3 ++
> > 2 files changed, 44 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/media/video/uvc/uvc_driver.c
> > b/drivers/media/video/uvc/uvc_driver.c index a1e9dfb..6bcb9e1 100644
> > --- a/drivers/media/video/uvc/uvc_driver.c
> > +++ b/drivers/media/video/uvc/uvc_driver.c
> > @@ -103,6 +103,11 @@ static struct uvc_format_desc uvc_fmts[] = {
> > .guid = UVC_GUID_FORMAT_BY8,
> > .fcc = V4L2_PIX_FMT_SBGGR8,
> > },
> > + {
> > + .name = "MPEG2 TS",
> > + .guid = UVC_GUID_FORMAT_MPEG,
> > + .fcc = V4L2_PIX_FMT_MPEG,
> > + },
> > };
> >
> > /*
> > ------------------------------------------------------------------------
> > @@ -398,6 +403,33 @@ static int uvc_parse_format(struct uvc_device *dev,
> > break;
> >
> > case UVC_VS_FORMAT_MPEG2TS:
> > + n = dev->uvc_version >= 0x0110 ? 23 : 7;
> > + if (buflen < n) {
> > + uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
> > + "interface %d FORMAT error\n",
> > + dev->udev->devnum,
> > + alts->desc.bInterfaceNumber);
> > + return -EINVAL;
> > + }
> > +
> > + strlcpy(format->name, "MPEG2 TS", sizeof format->name);
> > + format->fcc = V4L2_PIX_FMT_MPEG;
> > + format->flags = UVC_FMT_FLAG_COMPRESSED | UVC_FMT_FLAG_STREAM;
> > + format->bpp = 0;
> > + ftype = 0;
> > +
> > + /* Create a dummy frame descriptor. */
> > + frame = &format->frame[0];
> > + memset(&format->frame[0], 0, sizeof format->frame[0]);
> > + frame->bFrameIntervalType = 0;
> > + frame->dwDefaultFrameInterval = 1;
> > + frame->dwFrameInterval = *intervals;
> > + *(*intervals)++ = 1;
> > + *(*intervals)++ = 10000000;
> > + *(*intervals)++ = 1;
> > + format->nframes = 1;
> > + break;
> > +
> > case UVC_VS_FORMAT_STREAM_BASED:
> > /* Not supported yet. */
> > default:
> > @@ -673,6 +705,14 @@ static int uvc_parse_streaming(struct uvc_device *dev,
> > break;
> >
> > case UVC_VS_FORMAT_MPEG2TS:
> > + /* MPEG2TS format has no frame descriptor. We will create a
> > + * dummy frame descriptor with a dummy frame interval range.
> > + */
> > + nformats++;
> > + nframes++;
> > + nintervals += 3;
> > + break;
> > +
> > case UVC_VS_FORMAT_STREAM_BASED:
> > uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
> > "interface %d FORMAT %u is not supported.\n",
> > @@ -724,6 +764,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
> > switch (buffer[2]) {
> > case UVC_VS_FORMAT_UNCOMPRESSED:
> > case UVC_VS_FORMAT_MJPEG:
> > + case UVC_VS_FORMAT_MPEG2TS:
> > case UVC_VS_FORMAT_DV:
> > case UVC_VS_FORMAT_FRAME_BASED:
> > format->frame = frame;
> > diff --git a/drivers/media/video/uvc/uvcvideo.h
> > b/drivers/media/video/uvc/uvcvideo.h index 45f01e7..e522f99 100644
> > --- a/drivers/media/video/uvc/uvcvideo.h
> > +++ b/drivers/media/video/uvc/uvcvideo.h
> > @@ -152,6 +152,9 @@ struct uvc_xu_control {
> > #define UVC_GUID_FORMAT_BY8 \
> > { 'B', 'Y', '8', ' ', 0x00, 0x00, 0x10, 0x00, \
> > 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> > +#define UVC_GUID_FORMAT_MPEG \
> > + { 'M', 'P', 'E', 'G', 0x00, 0x00, 0x10, 0x00, \
> > + 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> >
> > /*
> > ------------------------------------------------------------------------ *
> > Driver specific constants.
>
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
