[Red5] Red5: audio and video out of sync resolved!

[Naicu Octavian]

Alo you must take into account that audio data has a higher priority than
video data over a rtmp connection.That's why you might get only just a few
video packets and most (if not all) audio packets over a slow connection.

-- 
Naicu Octavian,
Project Manager for AVChat
http://www.avchat.net

On 24/11/2007, 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.
>
>
> 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 ...
>
> Regards,
> Oleg
>
>
>
>
>
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