View Full Version : Missing first few seconds of sequential streams

Paul Webster
2007-07-15, 10:03
While waiting to see if RadioTime would support my request for On Demand being usable by SlimServer
( http://forums.slimdevices.com/showthread.php?t=36829 )
I decided to put one for Car Talk into WikiRadio.
However, this then highlights a problem.
The link is to a .smil file that contains a number of segments of the show. When played on a PC using whatever it defaulted to (can't remember what it was) ... it worked fine. However, when playing it back through SlimServer (and I guess mplayer) it loses the first few seconds of each segment.
My guess is that people tend not to notice this when playing a regular internet stream because once it starts it just keeps running. But when a show is in segments and tend to follow a defined pattern (a new caller starts a new segment and almost always introduce themselves ... and you miss it via Slimserver) then it is more obvious.

(running 6.5.3 from release day)

I haven't yet checked to see if this is a known problem - but I will search now. I thought that you might like to know that Car Talk is now available on WikiRadio first (they changed their URL syntax a while ago - so that it no longer changes from week to week so is now much more maintainable - i.e. doesn't need to be edited once a week).

2007-07-15, 10:32
mplayer chops off a number of seconds at the end of a RealAudio file/segment - I never noticed the beginning. There are also start and end time values which may be causing an issue - the SMIL file needs to be exmained to see if this is the reason.

What version of mplayer are you using ?

Paul Webster
2007-07-15, 12:39
There are no offsets in this .smil file.
However, mplayer looks quite old (I had - erroneously I suspect) thought that the 6.5.3 upgrade would have brought in the latest version - but I suspect that it is not included in the standard distribution ... I'll check later) - anyway it is
1.0pre8-3.4.2 from 2006

I'll get a more recent one and see if it changes things.

Paul Webster
2007-07-15, 18:43
... later ...
the version I was running is the one that AlienBBC provides - but I did find that there is a more recent version over on mplayerhq - so I am now running 1.0rc1-3.4.2 and am hitting the same problem.

I guess this means that I have to report it to mplayer itself - but could someone else confirm the problem first?

From Squeezebox (with AlienBBC/mplayer installed)
Internet Radio/Wiki Radio/Car Talk/Car Talk <play>
at the end of segment one you should hear the next caller introduce themselves ... I do from PC ... but not from Squeezebox.

Paul Webster
2007-07-22, 00:34
Can someone else try this and report back?

2007-07-22, 01:07
I'm still trying to find out the difference - at the start I think there may be 1 or 2 secs ?

As an alterntaive have you tried thre podcast by putting this into the Podcast Plugin

Paul Webster
2007-07-22, 02:03
I'm still trying to find out the difference - at the start I think there may be 1 or 2 secs ?

As an alterntaive have you tried thre podcast by putting this into the Podcast Plugin

The podcast is just the call of the week (in general anyway) - hence it is just one segment - so does not have the same problem - hence me adding the full current show link to Wiki Radio.

The comparison takes about 20 minutes - 10 minutes from wiki radio (i.e. to cover 2 segments| - and then take the same URL in wiki radio and drop it into a regular PC player.

In general - each call is a new segment ... so when you hear it on the Squeezebox you will probably not get the caller name/location and possibly the start of the question.

2007-07-22, 02:26
The podcast is timed at 54 mins - how long is the full show ?

Paul Webster
2007-07-22, 02:30
My apologies - I didn't check it but relied on memory.
Am doing so now.

Paul Webster
2007-07-22, 02:36
OK - podcast is fine. However, it is a single MP3 file of the whole show - so the joins are seamless.

I was using the Car Talk .smil as an example of a problem with SlimServer/mplayer - and although an effective alternate approach exists for Car Talk - the real underlying problem is still there (at least when I listen).

2007-07-22, 03:22
You weren't mistaken about the Podcast - there are 2 podcasts - Full Show and Call of the Week.

The advantage of using the RealAudio stream for all the NPR stuff is the ability to skip forward/backward.

I think you are probably right about mplayer but I also think it cannot be easily changed. I think mplayer when presented with a stream of data (it can come from a file), searches for the start of a recognisable audio block and then once identified, decodes the stream. This means it can handle fragments of audio streams which RealPlayer will not play. The side effect is the 1st block mayhhave no "signature" and so is discarded. This is just a theory.