[vlc] Re: PVR250 + 802.11g + VLC

[Jeremy Ardley]

Latency is a direct function of the ratio of I, B & P frames.  To get low
latency you need to have lots of I frames. no B frames and minimal P frames.
YYou should check your card settings to see if you can tweak this. The MPEG
standard specifies the encode/decode latency should be under 150 ms.  In
practical terms, 250 ms produces acceptable results at 4 Mbps '4CIF'
resolution going hardware to hardware.

The other factor is the decoder/viewer.  It needs to be specially tweaked to
go into low latency mode.  Software streaming decoders usually pre-buffer
several seconds of content before starting to play. For security
applications this buffering is not required nor wanted.


From: "Philip Edelbrock" <phil at edgedesign.us>

>
> I did some testing last night and the latency was about 1.5 - 2 seconds
> with the hardware mpeg-2 encoder card streaming to a wireless laptop.
>
>
> Phil
>
> Phung Chi Kien wrote:
>
> >Hi,
> >I very interrested in VideoLan in streaming live video for my security
> >project. I had the delay time about 2 ~ 3 s when I used V4L video capture
> >card (I think this delay time = encoding mpeg by ffmpeg at sending PC +
> >decoding mpeg by ffmpeg at receiving PC). Can you tell me about the delay
> >time due to the PVR250 encoding mpeg with the real live TV. I hope PVR250
> >can reduce the delay time a half at sending PC.

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