[Live-devel] 答复: question about the live555 RTP sending speed

[Aiden_Coomo]

HI, Malte!

    Thanks,

    The following blue notes are my questions.

 

 

-----邮件原件-----
发件人: Malte Tancred [mailto:malte at frontbase.com] 
发送时间: 2008年9月24日 13:56
收件人: live-devel at ns.live555.com
主题: Re: [Live-devel] question about the live555 RTP sending speed

 

On 23 sep 2008, at 15.11, Ross Finlayson wrote:

 

> The transmission speed is determined by the value of the  

> "fDurationInMicroseconds" variable.  Your "*Framer* object (in this  

> case, your "H264VideoStreamFramer" subclass) needs to properly set  

> this for each H.264 NAL unit that it delivers.

 

 

 

I suppose this is correct. However, "properly set" doesn't necessarily

mean what you first think it means. These are my findings:

 

- all NAL units that belong to the same frame, except the last NAL

   unit in that frame, should have a duration of 0 (zero).

 

[Aiden: ] : what's the meaning of " duration ", I guess, your mean’s that
the consecutive nal units in the same frame have the same timestamp, right?

 

- the last NAL unit in each frame should have a duration matching

   that of its frame.

[Aiden: ] : now, my all NAL unit in an access unit have the same timestamp.
Is it accord with your meaning?

 

- all NAL units in a frame should have the same presentation time.

[Aiden: ] : what’s the presentation time? ---- Timestamp ?

(Please note that what I call "frame" above is called an "access unit"

in the liveMedia library)

 

 

What brought my attention to this was the following message to the list,

regarding zero duration "frames" delivered by the MPEG stream framer:

 

   http://lists.live555.com/pipermail/live-devel/2004-April/000650.html

 

 

Regards,

Malte

 

 

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