Re: [AVT] Audio/Video and packet loss

On Apr 21, 2006, at 2:33 PM, Dave Singer wrote:

> At 14:42  -0300 21/04/06, Alejandro Cabrera Obed wrote:
>
>> Hi people, I have a brief question....
>>
>> In general, which type of media flow (audio or video) is more  
>> affected with packet loss in an IP network ???
>>
>> Is this just dependant on the CODEC algorithm used by the audio or  
>> video or maybe there is a media that is more sensitive for any  
>> given reason ???
>>
>
> In general, video tends to be more affected than audio.  The reason  
> is that audio tends to encode each time-interval independently, or  
> almost so (AAC, for example, needs two consecutive frames for the  
> second to be *perfectly* decoded), whereas in video, extensive  
> frame-differencing is usually done

    but if the video was also compressed frame by frame only (i.e.M- 
JPEG), or better yet not compressed at all, doesn't a dropped audio  
packet  impair a users perception of media quality, more than a  
dropped video packet?
   mostly because we are less tolerant of audio glitches, and more  
forgiving with video

> ('motion estimation' and so on). That means that an error affects  
> not only the frame for which data was lost, but also any frame  
> which predicts from the incorrect portion of that frame.  This  
> causes 'ghosting' and other artifacts that can persist for some  
> time (until those regions are painted again with correct data).   
> The affect can be mitigated but not eliminated by estimating what  
> was lost, and so on.
>
> Hope this helps
> -- 
> David Singer
> Apple Computer/QuickTime
>
> _______________________________________________
> Audio/Video Transport Working Group
> avt@ietf.org
> https://www1.ietf.org/mailman/listinfo/avt
>

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