[MPlayer-users] Strange Observation for PSNR calculation, frame drop , help needed

[RuthLess Konqueror]

Hi ,
       I have performed a couple of experiments  using the mplayer . Created foreman_qcif_64.mov , from  .yuv (I420) using ffmpeg and then hintin git with the Quick time professional.  Total number of frames were 5335.
 
 
 I have then used the Darwin Streaming Server (DSS) to stream the same.
 
 First , I streamed it in the wireless medium accessing the DSS through a wireless connection  ... 
 
 In order to calculate the psnr I used dumpvideo option to dump the video
 
 mplayer 'rtsp://xxx.xx.xx.x/foreman_qcif_64.mov'  -ao  null -nosound -dumpstream  
 which generates the stream.dump.
 
 Initially used the vidpsnr to compare the psnr  using the following command ..
 
 vidpsnr -o foreman_qcif_64.mov   -c stream.dump -l log.csv  
 
 got the following result 
 
 5326 frames          AVG PSNR =   "14.43181227186313690016", 
 
 pretty low psnr.  
 
 Repeated the same , using a wired connection and got the following 
 
 5331 frames AVG PSNR =  "14.78493324045271882519"
 
 No significant difference between wired and wiresless performance and pretty low psnr.  
 
 My understanding is that , since some frames are getting dropped , when I am calculating the PSNR , I am actually comparing between frames which do not have one-to-one correspondence between the original movie and the  stream dumped movie and hence such low values in PSNR .  
 
 Is it the right conclusion ? 
 
 if so , then how do I maintain the  correspondence between the frames of original movie and the stremaed movie. How do I get the right PSNR ? 
 
 Also how do I detect which frames were dropped ? 
 
 Any help or suggestion would be greatly appreciated.
 
 Thanks in Advance,
 
 --Ruthless 
  
			
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