[Bug 795416] New: x264enc: Make sure sinkpad caps are never renegotiated

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Bug ID: 795416
Summary: x264enc: Make sure sinkpad caps are never renegotiated
Classification: Platform
Product: GStreamer
Version: unspecified
OS: All
Status: NEW
Severity: normal
Priority: Normal
Component: gst-plugins-ugly
Assignee: gstreamer-***@lists.freedesktop.org
Reporter: ***@gnome.org
QA Contact: gstreamer-***@lists.freedesktop.org
GNOME version: ---

See commit message

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

--- Comment #1 from Thibault Saunier <***@gnome.org> ---
Created attachment 371174
--> https://bugzilla.gnome.org/attachment.cgi?id=371174&action=edit
x264enc: Make sure sinkpad caps are never renegotiated

This is not supported and we should NNE if upstream is not able to
handle that restriction.

This currently leads to totally broken behavior where the library
fails and we send EOS downstream without even posting an ERROR.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Thibault Saunier <***@gnome.org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Blocks| |795420

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Sebastian Dröge (slomo) <***@coaxion.net> changed:

What |Removed |Added
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CC| |***@coaxion.net

--- Comment #2 from Sebastian Dröge (slomo) <***@coaxion.net> ---
In bytestream mode this should work just fine, or not? And in avc mode as long
as downstream supports it. qtmux could support it but does not, matroskamux
can't support it, for others I don't know.

You would basically have to drain and then recreate the encoder.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Nicolas Dufresne (stormer) <***@ndufresne.ca> changed:

What |Removed |Added
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CC| |***@ndufresne.ca

--- Comment #3 from Nicolas Dufresne (stormer) <***@ndufresne.ca> ---
I like your idea of returning fixed caps to indicate the re-negotiation is not
supported. but x264enc should likely supports this. So I'd say, leave this bug
open if you decide to merge the disablement.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

--- Comment #4 from Thibault Saunier <***@gnome.org> ---
I indeed am exaggerating the fact that x264enc *can't* renegotiate at all :-)

This works just fine for instance:

export TMPSCENARIO=$(mktemp)
echo 'set-property, playback-time=1.0, target-element-name=capsfilter,
property-name=caps, property-value=(GstCaps)"video/x-raw,width=16,height=16"' >
$TMPSCENARIO
GST_VALIDATE_SCENARIO=$TMPSCENARIO gst-validate-1.0 videotestsrc
num-buffers=60 ! capsfilter name=capsfilter
caps=video/x-raw,width=640,height=460 ! videoconvert ! x264enc tune=zerolatency
! decodebin ! autovideosink /test.scenario


(Encode and decode + playback a testsrc at 640x460 for 1 sec then change it to
16x16)


There still is a negotiation issue in the x264enc (and in encoders in general)
as I can see totally broken behaviors rendering simple GES timeline (without
forcing the incoming video format). I will try to provide scenarios to
reproduce outside of it and we should work toward fixing it at the root in each
encoder, so I am not closing this bug.

For now I have the impression my best bet is to follow this approach instead:
https://bugzilla.gnome.org/show_bug.cgi?id=795464 as it is less controversial
and fix my issue just as well.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Thibault Saunier <***@gnome.org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Attachment #371174|none |rejected
status| |

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

Olivier Crête <***@ocrete.ca> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@ocrete.ca

--- Comment #5 from Olivier Crête <***@ocrete.ca> ---
Changing the caps is also an important behaviour for adaption for video calls,
so this bug should be able any bug in this behaviour in x264 that you can
reproduce.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=795416

GStreamer system administrator <***@gstreamer.net> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |OBSOLETE

--- Comment #6 from GStreamer system administrator <***@gstreamer.net> ---
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