Reducing latency produced from software decoding...

[NoAffinity]

I am testing a low-latency MPEG-2 hardware encoder, which has both ASI and IP (RTP) output. Latency for both outputs is expected to be approximately 30-60ms, and this has been confirmed for the ASI port. Via the IP port (receiving the stream with VLC), I am seeing roughly 300-500ms, however, and at this point my assumption is software decoding is adding the additional latency...and I would ultimately like any suggestions for what could potentially reduce this.

The receiving/decoding PC is connected to the encoder's IP output (both ethernet connections are gigabit) via cross-over cable. The PC is:

P4 3.2 GHz
2 GB DDR400 (dual channel)
Onboard VGA
Windows XP Pro

My initial thoughts as to what could potentially reduce latency are a) CPU and chipset, b) high-end video card, c) ...? Would a newer chipset, CPU, etc offer more efficient decoding with VLC? What about a high-end video card....does VLC take advantage of hardware decoding at all? Would OS make any difference (Windows vs. Linux vs. ?)? Any other thoughts?

All input greatly appreciated.

[The DJ]

--udp-caching has a default value of 300ms

[NoAffinity]

How can this be altered, in the Windows version specifically, but also in the Linux version? Is it possible to reduce to 0ms? Would this also affect RTP streams?

[DJ]

Doubtful the player would continue to function. VLC is a packet based player that does require a cache. Preferences does allow you to change the values for most of the protocols.

[ianarcher]

How can this be altered, in the Windows version specifically, but also in the Linux version? Is it possible to reduce to 0ms? Would this also affect RTP streams?

You can do it with that flag --udp-caching <myvalue>

If you're running two instances of vlc (one which is streaming), I believe outbound udp caching is involved. This can be tailored with --sout-udp-caching.

[NoAffinity]

I did find the value in preferences. Thanks for the input, and for the flag information.