[gst-devel] preroll (was: Re: [gst-cvs] thomasvs gstreamer: gstreamer/docs/random/ds/)

[Thomas Vander Stichele]

Hi,

> Speaking of preroll:
> Do we have a benchmark or other demonstartion that illustrates the need of
> prerolling?
> 
> The only justification for preroll I keep hearing is that Jorn had issues
> (iirc that was slowly pausing pipelines, which is not even an issue with
> preroll, but whatever). And the only hard benchmarking data I have tells
> me that mp3 pipelines need 0.02 seconds before they start playback and
> vorbis audio 0.07 seconds. (tested with gstreamer/tests/spidey_bench
> file.ext) And I don't think those times are an issue.

Forgot to reply to this part.  The human ear has a time resolution of
about 0.05 secs.  This is one of the reasons why ATRAC uses frame sizes
of about this size - which you'll notice when using minidisc machines,
because when you splice in them that's the resolution you get.  So your
0.07 seconds for vorbis audio is unacceptable.

In other cases, it will be even worse.  If you want to write a dj app
and start an ogg and a wav at the same time, knowing that they have a
starting beat at the same time, what will it sound like if the vorbis
takes 0.07 sec to start and the wav 0.01 ?

Thomas


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