[Bug 668329] [decklinksrc] - Drop 1400 frames per second abnormally.

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=668329
  GStreamer | gst-plugins-bad | 0.10.35

--- Comment #13 from Vincent Penquerc'h <vincent.penquerch at collabora.co.uk> 2012-01-28 16:06:31 UTC ---
For any codec, and any reasonable time slice T, you can find a
resolution/quality at which a frame takes longer to encode than T.

Most of the performance inherent in encoding in a given format lies in the
library implementing the particular codec

If encoding with a particular codec using GStreamer is significantly slower
than it would be using that codec's sample encoder (as in, a significantly
different ratio than with ohter codecs), then either there is a bug in
GStreamer (whether in the encoder element or elsewhere), or there is different
input (eg, larget video, etc), or that element does not make use of some
feature of the encoding lib (eg, multithreading). Maybe other reasons, but
there's at least three obvious ones.

If a given lib is signifiantly slower than others, it may be because it
involves
 more complex calculations, because it hasn't been optimized, because it's
build without asm opts for the platform, etc.

So it requires some common sense to decide whether there is a bug in GStreamer
here, and it would require investigating each of these points. Otherwise it's
like hearing there was a car accident and say "there is a bug in the car!".

So I think the two things you need to do (in general, not on this bug
particularly) are:
- to not stop at the first symptom when something does not work
- to apply common sense when trying to interpret these symptoms, to inform
further investigation


Now, if you think this bug should be reopened because Stuff Is Too Slow, then
you should check whether gst is significantly slower at something than the same
something without gst (eg, using the same input/settings as the codec's sample
encoder), then do some basic investigation as to whether it's a bug in gst
(something that's meant to work but does not) or merely something that gst
could do better. The first is a bug, the second an enhancement, but both seem a
valid report at first glance.

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