A/V synchronization

[Arvind]

Hi,

I have a question regarding A/V synchronization and would really
appreciate it if you could share your thoughts on it. I am looking at
DVB-H, where the the use of RTCP is not possible since there is no
feedback channel.

The SDP corresponding to an A/V program shows the video part uses H.264
encoding with 90KHz clock used for generating RTP timestamps. The
audio is encoded using AAC-HBR with 44.1KHz used for generating RTP
timestamps.

Are clocks derived from a common clock used at the sender to obtain the
audio and video timestamps?

At the receiver, is the following procedure employed
1. Separate clocks (one for audio and one for video) are reconstructed
from the audio and video timestamps.
2. Playout of audio and video done based on its clock, but lip synch is
achieved since a common clock was used to derive the audio/video clock
at the receiver

Or is there some way to link together the audio and video more closely
at the receiver?

Thanks for your time. I look forward to hearing from all u experts out
there.

Thanks,

Arvind