> On Wednesday, May 18, 2011 06:10:43 Bhupesh SHARMA wrote: > > Hi, > > > > (adding alsa mailing list in cc) > > > > > On Thursday, May 12, 2011 18:59:33 Charlie X. Liu wrote: > > > > Which HDMI receiver chip? > > > > > > Indeed, that's my question as well :-) > > > > We use Sil 9135 receiver chip which is provided by Silicon Image. > > Please see details here: > http://www.siliconimage.com/products/product.aspx?pid=109 > > > > > Anyway, this question comes up regularly. V4L2 provides timestamps > for > > > each > > > frame, so that's no problem. But my understanding is that ALSA does > not > > > give > > > you timestamps, so if there are processing delays between audio and > > > video, then > > > you have no way of knowing. The obvious solution is to talk to the > ALSA > > > people > > > to see if some sort of timestamping is possible, but nobody has > done > > > that. > > > > I am aware of the time stamping feature provided by V4L2, but I am > also > > not sure whether the same feature is supported by ALSA. I have > included > > alsa-mailing list also in copy of this mail. Let's see if we can get > > some sort of confirmation on this from them. > > > > > This is either because everyone that needs it hacks around it > instead > > > of trying > > > to really solve it, or because it is never a problem in practice. > > > > What should be the proper solution according to you to solve this > issue. > > Do we require a Audio-Video Bridge kind of utility/mechanism? > > I don't believe so. All you need is reliable time stamping for your > audio > and video streams. That's enough for userspace to detect AV sync > issues. > Hi Hans, I have another doubt regarding the framework choice for the entire system that I have, especially the video part of the system. The overall system is similar to the one depicted below: HDMI data --> HDMI receiver chip --> Video Port IP on SoC --> System DDR HDMI data is received from external world (from say a set-up box or dvd player), which is fed to the HDMI receiver chip on-board and then parallel data lines feed this data to a Video Port IP on the SoC which has a DMA master interface and hence can push the data thus received directly on system DDR. Now, I can figure out that there will be two drivers required here: # HDMI receiver chip driver (which is essentially a v4l2 subdev being controller via I2C) # Video Port driver (which is a v4l2 bridge driver) Is my understanding correct? Are there any HDMI receiver subdev driver and video bridge driver already available which I can use for reference? Also will the audio ALSA driver fit as a subdev driver in the entire system? P.S. I use the terminology 'bridge' and 'subdev' as mentioned in 'v4l2-subdev.h' header file. Regards, Bhupesh > Regards, > > Hans > > > > > Regards, > > Bhupesh > > > > > > > > > > > > > -----Original Message----- > > > > From: linux-media-owner@xxxxxxxxxxxxxxx > > > > [mailto:linux-media-owner@xxxxxxxxxxxxxxx] On Behalf Of Bhupesh > > > SHARMA > > > > Sent: Wednesday, May 11, 2011 10:49 PM > > > > To: linux-media@xxxxxxxxxxxxxxx > > > > Cc: Laurent Pinchart; Guennadi Liakhovetski; Hans Verkuil > > > > Subject: Audio Video synchronization for data received from a > HDMI > > > receiver > > > > chip > > > > > > > > Hi Linux media folks, > > > > > > > > We are considering putting an advanced HDMI receiver chip on our > SoC, > > > > to allow reception of HDMI audio and video. The chip receives > HDMI > > > data > > > > from a host like a set-up box or DVD player. It provides a video > data > > > > interface > > > > and SPDIF/I2S audio data interface. > > > > > > > > We plan to support the HDMI video using the V4L2 framework and > the > > > HDMI > > > > audio using ALSA framework. > > > > > > > > Now, what seems to be intriguing us is how the audio-video > > > synchronization > > > > will be maintained? Will a separate bridging entity required to > > > ensure the > > > > same > > > > or whether this can be left upon a user space application like > > > mplayer or > > > > gstreamer. > > > > > > > > Also is there a existing interface between the V4L2 and ALSA > > > frameworks and > > > > the same > > > > can be used in our design? > > > > > > > > Regards, > > > > Bhupesh > > > > ST Microelectronics > > > > -- > > > > 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 > > > > > > > > > > > -- > > > 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 > > > > > > > > > > > > -- > > > regards > > > Shiraz Hashim > > > > -- 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
