> On Saturday, June 18, 2011 21:11:37 Christian Gmeiner wrote: >> Hi all, >> >> I am still in the process of porting a driver to v4l2 framework. This >> device is capable of decoding MPEG-1 and MPEG-2 streams. > > Are we talking about decoding multiplexed streams or elementary streams? > E.g., audio+video or just the elementary video stream? > We are talking about elementary video stream only. > For decoding elementary streams pixelformats are being defined in an > RFC by Kamil Debski: > > http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/34229 > That would fix the problem I have - fine. > For multiplexed streams ivtv just uses V4L2_PIX_FMT_MPEG which can be used > for any MPEG program or transport stream. There is currently no method of > communicating to userspace which audio/video formats inside that PS/TS stream > are supported. > > The problem is that that information is hidden inside the stream. If your > hardware does multiplexed stream decoding, then what happens when you give > it an mpeg stream with unsupported codecs? Does the hardware give an error? > > Regards, > > Hans > >> See http://dxr3.sourceforge.net/about.html for more details. >> So I have programmed this: >> >> static int vidioc_enum_fmt_vid_out(struct file *file, void *fh, >> struct v4l2_fmtdesc *fmt) >> { >> if (fmt->index > 0) >> return -EINVAL; >> >> fmt->flags = V4L2_FMT_FLAG_COMPRESSED; >> fmt->pixelformat = V4L2_PIX_FMT_MPEG; >> strlcpy(fmt->description, "MPEG 1/2", sizeof(fmt->description)); >> >> return 0; >> } >> >> There is nothing in struct v4l2_format which indicates MPEG1, MPEG2 or >> MPEG4. As a result >> of this, it is not possible to return -EINVAL if somebody wants to >> decode/playback MPEG4 content. >> >> Any ideas how to achieve it? >> >> Thanks >> -- >> Christian Gmeiner, MSc >> -- >> 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 >> >> > -- Christian Gmeiner, MSc -- 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
