[vlc-devel] Zero-latency VLC

Maurizio Sciglio maurizio.sciglio at gmail.com
Thu Jul 5 11:15:17 CEST 2012

Thanks David.

In my case I'm using x264 with the zerolatency settings for my encoding
Being a RTSP/RTP stream, VLC is using the Live555 demux. Can anyone confirm
whether the parameters from the SDP descriptor would affect internal
buffering and introduce latency? I went through the code of Live555 and I
couldn't find any obvious source of internal latency. Any suggestion? I
also tried decreasing the Live555's RTP packet reorder size but I couldn't
notice any difference.


On Thu, Jul 5, 2012 at 8:46 AM, David Glaude <david.glaude at gmail.com> wrote:

> If memory serve me well,
> Hi did some attempt at Low-Latency VLC is about the same condition except
> that my source is not H.264 but plain simple MPEG4 (I think Part 2 rather
> than Part 10) and is also a low lattency encoder. Some of my attempt might
> have translate into question on this mailing-list and even some ticket on
> trak.
> Depending on how your RTSP/RTP stream is describe, the effect of the
> buffer control parameter might be different. My multicast stream (wich is
> video only) was described by some an ASX file but not the recovered by RTSP
> DESCRIBE but either a local file or by doing an HTTP GET. Because my input
> is video only, there is no sync problem that could increase the lattency.
> So you have to find wich input module is used by VLC, in my case it was
> LIVE from LIVE555.
> From my logs, It seems that I was using "--rtsp-caching=120" (I have also
> seen "--caching=160" is some of my attempt). What I remember is that there
> was some lower limit and whatever value I was trying it was not going below
> that limit.
> Also, I have discovered that in recent version, VLC try to increase the
> input buffering when starvation occure... but this can be disabled by using
> "--clock-jitter=0"
> My main problem was "stability" of the lattency. Overtime and especially
> if there were some network disturbence (packet loss), VLC would be less and
> less in sync with the source (I need it to work for 4 days in a raw at the
> minimum) and it is the (not well supported) vlc plugin I would use in final
> version. My benchmark was QT that as some non compressible 3 second of
> buffer... but this is stable over time.
> Please share the knowledge you have already accumulated.
> Anyway, I need to redo some test with lattest version.
> David Glaude
> 2012/7/5 Maurizio Sciglio <maurizio.sciglio at gmail.com>
>> Hi Guys,
>> I'm trying to figure out whether VLC can be used to play a H.264 video
>> streamed using RTSP/RTP with (virtually) zero latency. By using
>> "network-caching" I managed to reduce the latency to ~80-100ms but if I try
>> to reduce it any further the video won't play at all.
>> I am aware that VLC hasn't been designed with that goal in mind but I
>> would greatly appreciate if you could suggest anything I could try or,
>> alternatively, areas of the code I could/should look into in order to
>> modify VLC for what I need.
>> Thanks!
>> Maurizio
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