[Mp4-tech] [System]Audio video sync

[Vinayak Pore]

Hello,
Bharat P. SONI wrote:
>Hi,
>
>Just few inputs!!
>
>In the first proposal there is possibility of slight 
>inaccurecy, but it may be acceptable. 
>  
>
This is dependent on the precision  of the timer and thread priority.  
So it is dependent on OS support and fast response of OS.
>Second proposal seems to be more deterministic in nature as 
>the interrupt from audio renderer have very high prioroty so 
>you can update the system time here quite accurately. The 
>problem I see is if due to some reason we are not able to 
>send enough data to the audio renderer (may be due to data 
>loss in the network) will this interrupt be called on time? 
>If not then we will have incorrect system time.
>  
>
This can be corrected. You will face same problem in every 
implementation. The solution is to send silence or repeat the part of 
the previous audio frame.
>Another problem (also related to the problem above) is that 
>in this case the system time is dependent on the audio. For 
>presentatin that may not have audio, your system have no 
>other option for clock.
>  
>
Again this can be solved by sending silence of appropriate duration to 
audio codec. So Video Only file also can be played.
If you keep the load on timer thread very low then total processor load 
can be brought down. I can not give you exact figures as the are very 
much dependent on OS, PRocessor and Clock and Size of video and 
decoding  but processor will get some free time.
>Regards,
>Bharat
>
>  
>

-- 
Best regards,
Vinayak.
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