[Red5] Red5: audio and video out of sync resolved!
steven.gong at gmail.com
Sat Nov 24 05:16:17 PST 2007
On Nov 24, 2007 8:50 PM, Oleg Kolokolov <scanwork1 at gmail.com> wrote:
> Hello Red5 community,
> It is more like a suggestion for the Red5 developers.
> We noticed while working with Red5 on our project (www.blipback.com) that
> when recording on a slow connection you may get a recorded FLV where audio
> and video are out sync badly.
> When such FLV is played back (no matter streamed from some remote location
> or downloaded and played locally)
> it looks like audio goes normally but video is very slow and out of sync
> and sometimes can even stuck for quite a time.
> We checked and figured out that in the incoming stream in
> such cases mostly audio packets arrive in the beginning
> and then video packets arrive with a huge delay.
> And the problem (as we understand it) is that Red5 just saves this incoming stream in this same order.
Red5 saves the incoming stream in the same order is just because the
incoming packets are generated by flash player per the timeline. So I don't
think it's a wrong behavior. Could you please tell me how you adjust the
packet order? Will be break the timeline of the packets?
> So when Flash plays back such FLV it gets the packets in the same order.
> So what it has - mostly audio packets in the beginning and plays back them normally but has no video packets to
> display and waits until they arrive so we see a frozen first frame or the
> last that arrived.
> This can be resolved on the client side (Flash
> player made so that it can resolve this) but for this the whole stream must
> be downloaded first. We think in this case Flash player does this reordering
> of the packets in memory and then plays it back. But this reordering takes
> time. That's bad because you must first wait until the stream is
> downloaded and then until it is processed in Flash
> player (which looks like hanging for a while).
> What we made in blipBack.com is modification of Red5 to reorder incoming
> packets in real time and save FLV already fully prepared to playback.
> May be it makes sense to add this modification to next rev of Red5?
> I wonder does Adobe Media Server do this? Seems so ...
> Red5 mailing list
> Red5 at osflash.org
InfraRed5 Red5 Consultant: http://www.infrared5.com, steven at infrared5.com
Red5 Developer: http://osflash.org/red5,
Modesty is an overrated quality in men of no great accomplishment. -- Ricky
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