Question

I have an application that plays back video frame by frame. This is all working. However it needs to have playback Audio too, when Audio and Video running simultaneously it seems, Video lagging behind audio,
Logic i am using to display the video frame as follows

 ProcessVideoThread(){

  // Read the data from socket, 

  // decode it : this is going to be in side libvpx library, after decoding i am getting raw     
  // bitmap data 

  // After getting raw bitmap data, use some mechanism to update the image, 
  // here i tried runOnUIThread, handler but 


 }

Now what is happening, it seems UI thread is getting very late chance to update the image, i.e. libvpx is taking approx 30 ms to decode the image and through runOnUIThread, its taking 40 more ms to update the image, but inside UI thread i am updating it.
Can anyone advise me, how can i reduce the delay to update the image on the UI thread.

Answer 1

Looks interesting. If i was in your situation, i would examine the following methods.

1) Try using Synchronization between Audio An Video Threads.

2) Try reducing the Video Frames where audio is lagging and reduce the audio frequency where Video is lagging.

You can do the same in the following way.

int i;
if(i%2==0)
ShowFrame();
else
i++

What this will do is that it will straight away reduce the Video Speed from 24 12. So the Audio will now match with video. But yaa quality will be at stake as i already mentioned to you. This method is called frequency scaling. Widely used method to sync audio and Video.

Refer to the following for clear understanding and ways in which you can sync audio and video. This is in relation to the FFMPEG. I dont know how much of it you will be able to use, but definitely it will help you to get some idea.

http://dranger.com/ffmpeg/tutorial05.html

All the Best..