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.
Regards,
Hans
Regards, Bhupesh
-----Original Message----- From: linux-media-owner@vger.kernel.org [mailto:linux-media-owner@vger.kernel.org] On Behalf Of Bhupesh
SHARMA
Sent: Wednesday, May 11, 2011 10:49 PM To: linux-media@vger.kernel.org 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-
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-- regards Shiraz Hashim