[gst-devel] BaseSink "sync" property

[Jon Burgess]

Hi all,


>> > Does turning sink off just result in the sink rendering it as soon as
>> > it gets data?
>>
>> Essentially, yes. Data is played when it arrives when sync=false. When
>> sync=true, it uses the timestamps on the buffers to wait for right time
>> for playback. If the playback is stuttering this is usually because of
>> a) starvation, something is not feeding data fast enough b) bad
>> timestamps c) not enough CPU power to decode things. a) is unlikely with
>> a default jitterbuffer of 3secs in rtspsrc c) is also unlikely if it's
>> smooth with sync=false. So, it's likely b) bad timestamps. Make sure you
>> have a recent ffmpeg package (reordered buffers had bad timestamps in
>> earlier versions). The payloader is probably fine, even for slightly
>> older versions.
>
>
> I think also it is unlikely a) or c), because my dev box is an el-cheapo
> Intel PC (where it works), and the test machine is a fairly new Dell server
> (where it doesn't work), so it has a lot more CPU power...
>
> I'll investigate b) though, especially since hardy ubuntu packages are
> likely a bit older than the most recent versions of things...
>

Just another thought I had while drifting off to sleep last night... :-)

One of the major hardware differences between my dev box (working) and the
test machine (stuttering), is that my dev box has a sound card, whereas the
test machine does not.  Could it be that one of the gstreamer
elements/clocks is trying to access the clock on the soundcard, and
therefore failing because of course there isn't one?

Having said that, I have done a couple of other tests on the test machine:

1) playback from a quicktime movie file containing mp4v video, no audio -
playback is smooth.
2) playback from a quicktime movie file containing h264 video + some sort of
mpeg audio - playback is smooth also, although get the following message:
"** Message: don't know how to handle audio/mpeg..." which I guess is
expected seeing as there is no soundcard.

Cheers,
Jono
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