[GStreamer] GST_STREAM_ERROR_TYPE_NOT_FOUND errors are skipped

• Component: Media
• Status: RESOLVED WONTFIX

[Fabien Vallée]

Tested on linux / gtk port / gstreamer 1.4.0 but same issue was already there long time ago in Qt port / gstreamer 0.10.19 
(code is very old, http://trac.webkit.org/changeset/83598).

When gstreamer send "GST_STREAM_ERROR_TYPE_NOT_FOUND" error, the error is skipped (= not reported to the MediaPlayerClient)

http://trac.webkit.org/browser/releases/WebKitGTK/webkit-2.4/Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp?annotate=blame&rev=172912#L1027

Definition of stalled event is : "The user agent is trying to fetch media data, but data is unexpectedly not forthcoming" 
http://www.w3.org/TR/2011/WD-html5-20110113/video.html#event-media-stalled

Definition of GST_STREAM_ERROR_TYPE_NOT_FOUND is "used when the element doesn't know the stream's type."
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstGError.html

GST_STREAM_ERROR_TYPE_NOT_FOUND doesn't seems related to "data is unexpectedly not forthcoming". I don't know why GST_STREAM_ERROR_TYPE_NOT_FOUND was chosen, but the code is very very old, so maybe gst was lacking some error type back then.

Anyway this cause troubles: when gstreamer try to play an invalid video, it will usually trigger GST_STREAM_ERROR_TYPE_NOT_FOUND.

I didn't find any 'stalled' related regression test, but in LayoutTests/media/broken-video.html, playback of LayoutTests/media/content/garbage.mp4 triggers 2 errors:

Error 4: Could not determine type of stream. (url=file:///xxxx/LayoutTests/media/content/garbage.mp4)
GST_STREAM_ERROR: 4, Could not determine type of stream.
Decode error, let the Media element emit a stalled event.
Error 1: GStreamer encountered a general stream error. (url=file:///xxxx/LayoutTests/media/content/garbage.mp4)
GST_STREAM_ERROR: 1, GStreamer encountered a general stream error.

First error (GST_STREAM_ERROR: 4) is skipped, but second error (GST_STREAM_ERROR: 1) is handled and the test can pass (but only because of the second error).

However if I change the video src to another invalid video (http://itv.mit-xperts.com/hbbtvtest/playerevents/novideo.php/video.mp4), only
"GST_STREAM_ERROR: 4, Could not determine type of stream" error is triggered.
As GST_STREAM_ERROR_TYPE_NOT_FOUND is skipped, the error event is never triggered and the test timeout.

Same test (using modified video src) works fine using chromium (Version 36.0.1985.125 (283153)) and opera 12.16.

[Fabien Vallée]

Created attachment 237484 [details]
based on LayoutTest/media/broken-video.html only changed the video src

test can pass using chromium (Version 36.0.1985.125 (283153)) and opera 12.16.
Fails (timeout, no event triggered) using webkitgtk.

[Fabien Vallée]

To correct my first comment, there are tests for 'stalled' event, e.g. :
LayoutTests/http/tests/media/video-play-stall.html
The test timeout as per https://bugs.webkit.org/show_bug.cgi?id=108925
but even if I increase run-webkit-tests timeout I don't think gstreamer is sending GST_STREAM_ERROR_TYPE_NOT_FOUND message in that case.

[Fabien Vallée]

Comment on attachment 237484 [details]
based on LayoutTest/media/broken-video.html only changed the video src

need to copy the file to LayoutTest/media/ folder to access media-file.js and video-test.js

[Philippe Normand]

This code was actually introduced in http://trac.webkit.org/changeset/81229 and I think that reverting it will break a test again.

[Fabien Vallée]

Yeah, I agree, anyway thanks Philippe for answer.
I will try to check what's going on in video-play-stall-before-meta-data.html

[Fabien Vallée]

won't fix.