audio video synchronization issue

[sujith kv]

I have a bit strange gstreamer pipeline and facing a audio video
synchronization issue with this while doing play/pause operation. My case
is little bit different. I have two process running in same computer.
Process1 sends the audio data to process2 using named pipe and video data
to a custom video sink in the same pipeline. Process2 reads the named pipe
using another gstreamer pipeline and playback the audio. Please see those
pipelines below.

process1 pipeline :
---------------------------
I have set playbin video-sink to custom-videosink and audio-sink to another
bin that sends the audio to named pipe.
 -------------
| playbin  | -> customvideosink
|             | -> gdppay -> filesink location=named pipe
--------------

process2 pipeline :
---------------------------
filesrc location=named_pipe -> gdpdepay -> alsasink

Scenario
-------------
1. I am setting process2 pipeline as PLAYING state by default
2. When I do PAUSE in the process1 pipeline, the process1 pipeline state
chaned to PAUSED. In this case the process2 pipeline will be in PLAYING
state only(not hearing any audio, but clock will be running). So I used
another named pipe mechanism to send a PLAY/PAUSE  control command to
process2. these commands will be read by another thread in process2 and set
pipeline state accordingly when user do PAUSE/PLAY in process1.
Is this is a relevant mechanism? Any other solution to control the process2
pipeline state other than this?

2. In the above mechanism, while I do PAUSE in process1, the video is
getting PAUSED immediately. but audio is PAUSED after few
milliseconds. This leads to lose in audio/video synchronization. What could
be the reason for this ?

Thanks in advance
Sujith
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