[gst-devel] AV synchronization problem with elementary AV (AAC/H264) streaming

[amitpandya]

Hi all,

I am doing the elementary streaming of AAC/H264 data using RTP over UDP with
gstreamer.

In my case, I have two separate pipelines for Audio & video as below.

video Case:(pipeline1)
appsrc->input_capsfilter->packatizer->output_capsfilter->gstrtpbin.
           
        where, appsrc is pushing H264 encoded data to pipeline    

Audio Case:(pipeline2)
appsrc->input_capsfilter->packatizer->output_capsfilter->gstrtpbin.
           
        where, appsrc is pushing AAC encoded data to pipeline

Now , the problem is at clientside(QT player) both Audio & Video playback is
happening fine but audio is delayed by several seconds (8-10 sec precisely)
than the video.

After primary debugging found that audio pipeline is taking more time in
processing and sending Audio Packets a bit late than the Video packets.Here
both the Audio - video processing is happening in different pipelines and
both pipelines have their own processing time, which is unfortunately
different.

In sort, Video pipeline start sending video packets much earlier & after
some time Audio pipeline starts sending Audio packets to the N/W.that is why
at client side video playbach happens first and after some delay audio
starts playing.

I have done following testing to resolve the problem.
1)Instead of two pipelines I used only single pipeline for both AV but it is
not making any difference.    
2)With single pipeline instead of using two different gstrtpbin (one for
Audio & one for Video) used only one gstrtpbin but that is not making any
difference.
3) Used queue elements in the pipeline to delay video pipeline still no
difference.

My question is how AV synchronization can be handled within the pipeline for
these case? or
I have to put some buffering mechanism outside gstreamer pipeline which can
handle such AV syncronization?If so how to do it?
  
Any help is greatly appreciated.

Thanks,
Amity Pandya
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