Sync problems - any advice please ?

[wifi-jack]

Hi everyone.

First off - a huge thank you to all involved for a fantastic program. I am amazed at what can be achieved with this system.

I am trying out a streaming project using VLC, and although I have had some success, I am having some problems synchronizing the transcoded
output. It starts out fine, but after a varying amount of time, it seems to be slipping the audio behind the video.

My system is using mumudvb to dump an entire transponder to unicast http addresses and then my transcoder machine uses this input to produce
FLV output to be displayed via my apache webpage, using flowplayer.

All of this works perfectly and the streams start, play and continue fine. When the audio has slipped, a restart of the individual stream returns it to
normal for a time.

I have the following channel configuration in VLM ......

Code: Select all

new CH1 broadcast enabled setup CH1 input "http://192.168.2.254:5000" setup CH1 output #transcode{vcodec=mp4v,venc=x264{profile=main,preset=fast,vbv-bufsize=3600,vbv-maxrate=1800,fps=25},acodec=mp3,ab=64,scale=.8,channels=2,samplerate=44100}:http{mux=ffmpeg{mux=flv},dst=192.168.33.1:8100/stream1.flv} setup CH1 option http-caching=1200 setup CH1 option sout-transcode-audio-sync setup CH1 option sout-transcode-deinterlace

I'm running Ubuntu 10.10 64bit OS, and VLC 1.1.7, although I have had this problem using versions 1.1.4, and 1.1.5.
Hardware is a dell quad-code Xeon for the transcoder, and an older Xeon dual core HP server with a Haupage DVB-T twin tuner card is
performing the tuner functions.

I have tried including audio-sync in the setup code, above but the result is the same. My stream parameters have been trial and error and borrowed
knowledge from here - I am not an expert in Linux or IPTV, but can manage to bumble my way round most things with a bit of effort.
It seems that the subject is so vast, and technical at it's core, that I am probably making a fundamental error somewhere.

Can anyone offer any advice on where I am going wrong here, or any pointers on where to go next ??
If the above looks reasonably sound, perhaps I need to direct my attention to the DVB decoding process, although, there doesn't
seem to be any problems with this output - it's all in sync etc.

Thanks in advance for any suggestions, and a general thanks to all the people who help, we, the lost souls of open source on a daily basis !!

Cheers,
Jack

RIP Gary Moore - "The King of the Blues", for some of us, anyway.

[Greg]

Take a look at this thread
viewtopic.php?f=4&t=86406
and the links therein

I guess we will have to wait until Videolan development has the rescources to fix the problem.

[wifi-jack]

Thanks for your reply Greg.

Well, I've read through the messages, and now I'm not sure where the problem is.

The first article seems to be that there is a generic time-stamping problem embedded in the V4L standard, and yet the second article
is implying that the problem is with versions of VLC post.1.0.6, running on anything later than Ubuntu 10.04.

So, in my ignorance, I'm confused, to be honest...... should I roll the server back to 10.04 and use an older version of VLC ?
or, is this issue a total wipeout for any project using Linux as a transcoding base ?
Is a Windows based solution not prone to this type of issue ?

I can't believe I've finally found a reason to use windows in preference to Linux !!!!

Sorry if I appear to be ignorant on this, but I'm just trying to understand what I can do to move forward, or whether I need to dump this track
and do it all over again using something else. That would be a big shame and a lot of time wasted.

Thanks again,

Jack.

[Greg]

So, in my ignorance, I'm confused

So am I , probably many others too

Is a Windows based solution not prone to this type of issue ?

If you ferret through the links and sub links, you may arrive here

viewtopic.php?f=14&t=86369

So it would seem in the case of DVB-T devices that the sync problems are present in Windows as well? So dumping the linux version in favour of Win may not solve it. My guess is that there is not a "The" problem, but perhaps several problems with the same audio sync symptom, but that is just my speculation.....

I really couldn't say if the problem is present in Linux - VLC 1.0.6 with a DVB-T capture device.
Perhaps if you are happy to try 1.0.6 with a DVB-T device and post back what happens or add to the bug report it might help toward a fix in the longer term.
I never got to the bottom of as to whether there were, or were not security issues related to 1.0.6 . As I understood (perhaps wrongly) 1.0.6 was a security fix, but was never released in the Win version as 1.1.x was at or about ready to release?
1.0.6 can be a bit quirky and unstable if you keep changing the parameters, I find it moderatly well behaved if set up and run in one hit.

I am in the process of trying 1.1.7 in Ubuntu with analogue capture bt878 card. If it does hold audio sync...? Then perhaps it narrows the problem down to DVB-T...? Not too much immediate help to you at the mo' but might help to a short term fix until the problem(s) are solved?

[wifi-jack]

O Wow !

This is going from bad to worse now ! ... I have to laugh or else I'll start crying for the amount of time I have wasted on this.

Can I throw this open please. to anyone reading this post ?

Is anyone running a >>working<< transcoding, streaming solution using Linux and VLC and DVB-S or DVB-T ?
Even .... gulp .... Windows ?

If so, could you share some insight please ? It would be very helpful to me personally, and I'm sure, to others who may be having
the same problems.

Cheers,

Jack.

[wifi-jack]

Nobody ?

[wifi-jack]

Hi all,

Thanks to some input from a regular contributor here, (thanks Greg!) I've managed to move past the problem I was getting.

It would seem that my audio sync problem was a joint effort between Ubuntu Server 10.10 (64bit) and VLC.

By downgrading the OS to 32 bit variety of 10.04LTS, and usign the repository standard 1.0.6 VLC, I may have lost a little performance,
but I do have a much more controllable system. VLC now doesn't lose sync every 20 minutes now. I sometimes get VLC crashes with
no logged details, and occasionally complete loss of audio on one or two channels, but these are fairly infrequent and diligent use of monit and
cron are keeping it moving.

I'm sure the sync problem will be fixed in a future release, but if anyone is having these kind of problems on Ubuntu, perhaps this will help
you to get something working, albeit, a little unstable.

Jack.