Theora video thumbnails corrupt
Closed, ResolvedPublic

Description

Author: camjsb7j9g

Description:
Test_20100411_Vdubtestrgbcube4secs_ifps.ogv with empty thumbnail

Between 03:23, 8 April 2010 and 08:40, 9 April 2010 new video uploads started to render with empty or corrupt thumbnails (Firefox, Google Chrome, Opera and Safari, with cache and file purging; thumbtime also tested). New uploads are still rendering incorrectly. I *believe* I have eliminated file corruption because the file uploaded is identical to the file on my PC (I download the file from mediawiki and use emacs to compare).

See http://commons.wikimedia.org/wiki/Commons:Village_pump#Video_thumbnails_corrupt_since_9_April

Duplicated problem on skins: Monobook, Vector and Classic. Other skins not tried.

How to replicate:

1: choose any small video from Category:Calibration videos at http://commons.wikimedia.org/wiki/Category:Calibration_videos and download to computer

2: upload same file with name prefixed with "Test_reupload_"; click the "ignore warning and save anyway" button

3: see the corrupt or empty video thumbnail

Example attached from: http://commons.wikimedia.org/wiki/File:Test_20100411_Vdubtestrgbcube4secs_ifps12fr12_q10.ogv


Version: unspecified
Severity: major
OS: Windows Vista
Platform: PC

Attached:

Details

Reference
bz23160
bzimport set Reference to bz23160.
bzimport added a subscriber: Unknown Object (MLST).

The empty thumbs are due to the fact that there are no key frames following the seek point (midway file). We should probably always start at frame 0 when a movie is under 10seconds.

The other issue is of a similar nature and also related to keyframes.

What triggered this behavior, i'm not sure of, but most likely ffmpeg was upgraded on the scalers. I have asked Roan, and the servers currently run r11872+debian_3:0.svn20080206-12ubuntu

If someone could run the following on a scaling server and extract the debug info from ffmpeg please. That might help:

ffmpeg -ss 9.5 -i /mnt/upload6/wikipedia/commons/b/bd/Translational_motion_gif.ogv -f mjpeg -an -vframes 1 ./test.jpg

I made an educated guess at the path. Might not be 100% correct.

I note that wmf-deployment has some OggHandler/OggHandler_body.php changes from mdale, that are not currently in wmf/1.16wmf4

  • Bug 23163 has been marked as a duplicate of this bug. ***

Is there a workaround, or are all thumbnails on new videos broken for now?

gmaxwell wrote:

The thumbnails for the files linked in in Bug 23163 don't really look like failing to decode starting at a keyframe. They look like the result of decoding with the broken theora encoder which was included in ffmpeg up until about a year ago.

At least of the cluster was upgraded to fix this at some point, but perhaps some old software is still out there on some systems.

(In reply to comment #4)

Is there a workaround, or are all thumbnails on new videos broken for now?

there is currently no workaround. When everyone has landed in Berlin, Tim Starling and/or Michael Dale will have to look at it probably.

gmaxwell wrote:

(In reply to comment #5)

with the broken theora encoder which was included in ffmpeg up until about a

*decoder* ugh.

http://lists.wikimedia.org/pipermail/wikitech-l/2010-February/046706.html < this thread is likely relevant too.

(In reply to comment #7)

http://lists.wikimedia.org/pipermail/wikitech-l/2010-February/046706.html <
this thread is likely relevant too.

Yes, that's exactly why I pointed out the differences between wmf-deployment and 1.16wmf4

Created attachment 7290
Debug output

Debug output as requested in comment #1.

Attached: debug.log

gmaxwell wrote:

The ffmpeg in that debugging output is too old. Even absent the seeking problems it will not reliably produce correct output.

mdale wrote:

there is also this code review comment from Tim that says that oggThumb is in fact oky?
http://www.mediawiki.org/wiki/Special:Code/MediaWiki/62223#c5744

... but would have to go into the "code review queue" ? But the fix was already in the deployment branch without any suggested changes. So Tim forgot to merge it before he deployed it ?

I can send a patch to make wmf4 what was once wmf-deployment adding in Tim's fix to bug 22388 ? Does that sound reasonable?

And we the other parts of oggHandler can go back into trunk for review ? ( i.e transcoding so have some basic consistency in the bitrates of embed videos ? )

mdale wrote:

Restored the previously deployed ( working ) oggThumb code to oggHandler trunk. r65149

Its kind of tricky to test since you need the svn version of oggThumb ( that has already been deployed )

TheDJ added a comment.Apr 18 2010, 3:26 PM
  • Bug 22100 has been marked as a duplicate of this bug. ***

mdale wrote:

any update on this?

Almost all newly uploaded videos continue to have broken thumbnails ...

Should I be giving opts people instruction to compile ffmpeg to deploy less broken thumbnailing?
Or can we put the code that was working for a few months back into operation while this gets sorted?

gmaxwell wrote:

FWIW— Yet another Ffmpeg-violates-the-spec causing failed decoding problem was discovered and fixed today. This isn't a case that people should have been hitting with any frequency but it's a reason to use only the most current development ffmpeg if ffmpeg is continued to be used.

camjsb7j9g wrote:

FWIW2- ffmpeg2theora version 0.24 is giving good thumbnails for me lately. Versions 0.25, 0.26 and from 2010-03-16 always gives garbled or missing thumbnails. For small examples see [http://commons.wikimedia.org/wiki/File:SDO 10 second youtube 1080 pixels DA8C8E04d01.flv 320x240 br270.ogv] and [http://commons.wikimedia.org/wiki/File:Solar Dynamics Observatory xo with ffmpeg2theora-0.24 320x240 br270.ogv]: scroll down to "Source" for the exact commands used to encode. I also posted this at [http://commons.wikimedia.org/wiki/Help_talk:Converting_video#Video_thumbnail_error] and [http://commons.wikimedia.org/wiki/Commons:Village_pump#Theora_thumbnails].

camjsb7j9g wrote:

(In reply to comment #16)

FWIW2- ffmpeg2theora version 0.24 is giving good thumbnails for me lately.
Versions 0.25, 0.26 and from 2010-03-16 always gives garbled or missing
thumbnails. For small examples see [http://commons.wikimedia.org/wiki/File:SDO
10 second youtube 1080 pixels DA8C8E04d01.flv 320x240 br270.ogv] and
[http://commons.wikimedia.org/wiki/File:Solar Dynamics Observatory xo with
ffmpeg2theora-0.24 320x240 br270.ogv]: scroll down to "Source" for the exact
commands used to encode. I also posted this at
[http://commons.wikimedia.org/wiki/Help_talk:Converting_video#Video_thumbnail_error]
and [http://commons.wikimedia.org/wiki/Commons:Village_pump#Theora_thumbnails].

The above URLs should read:

http://commons.wikimedia.org/wiki/File:SDO_10_second_youtube_1080_pixels_DA8C8E04d01.flv_320x240_br270.ogv

and

http://commons.wikimedia.org/wiki/File:Solar_Dynamics_Observatory_xo_with_ffmpeg2theora-0.24_320x240_br270.ogv

also

http://commons.wikimedia.org/wiki/File:Helioseismic_and_Magnetic_Imager_First_Light_Briefing_320x180_ffmpeg2theora-0.24.ogv

I've rewritten the oggThumb support in OggHandler and I've made some substantial changes to oggThumb itself in a development branch on sf.net. I'm going to try handing this over to Mark Bergsma for packaging.

Fixed now. Any remaining cases should be fixable by doing action=purge on the image description page followed by forced refresh (e.g. shift-reload in Firefox).

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