MLT Multimedia Framework / Bugs / #57 render contains artifacts (white little dots)

Dan Dennedy - 2010-03-18

status: open --> pending

labels: 1163776 --> avformat module

assigned_to: j-b-m --> nobody
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Dan Dennedy - 2010-03-18

Not enough information to reproduce.

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Fabio Varesano - 2010-03-19

Well.. I don't really know what else to add.. I attached at http://www.kdenlive.org/mantis/view.php?id=1509 the file example.avi which is a piece of the source video.. If I put it into kdenlive I get the white artifacts, no matter how I setup the rendering and also on the project monitor.

For example, I get visible artifacts if I insert the example.avi file in the kdenlive timeline and I more to 4:16 (sec:frame).. You see the artifacts in attached file artifacts.png.

Please let me know what else can I give you to troubleshoot this issue. Artifacts are there I'm not imagining them.

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Fabio Varesano - 2010-03-19

status: pending --> open
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Dan Dennedy - 2010-03-21

Thank you for the sample input. I am not denying your claim; I saw them on your ogg output as well. I am simply saying I could not reproduce it or that I have not seen it yet, even with your example.avi. I suspect it might be related to your version of FFmpeg or something in the way FFmpeg or MLT are built (e.g. compiler optimization).

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Fabio Varesano - 2010-03-22

All my packages are from Archlinux Current x64. I'm able to recompile all the packages to the way you suggest to fix the issue. I could even give you ssh access to my machine if you want to troubleshoot this remotely.

See below for details on my current packages.

Build script for mlt:
http://repos.archlinux.org/wsvn/community/mlt/repos/community-x86_64/PKGBUILD
Build script for ffmpeg
http://repos.archlinux.org/wsvn/packages/ffmpeg/repos/extra-x86_64/PKGBUILD

[fabio@gamma ~]$ ffmpeg -v
FFmpeg version SVN-r22511, Copyright (c) 2000-2010 the FFmpeg developers
built on Mar 13 2010 19:35:54 with gcc 4.4.3
configuration: --prefix=/usr --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libfaac --enable-libfaad --enable-libxvid --enable-libx264 --enable-libtheora --enable-postproc --enable-shared --enable-pthreads --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-version3 --enable-nonfree --enable-runtime-cpudetect
libavutil 50.12. 0 / 50.12. 0
libavcodec 52.59. 0 / 52.59. 0
libavformat 52.55. 0 / 52.55. 0
libavdevice 52. 2. 0 / 52. 2. 0
libswscale 0.10. 0 / 0.10. 0
libpostproc 51. 2. 0 / 51. 2. 0

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Dan Dennedy - 2010-03-23

I was using an older version of FFmpeg. I just updated to SVN-r22641. I built it using similar options to Arch minus some --enable-codecs. Then, I built MLT similar to Arch package. In particular, normally I do not disable mmx and sse2. Why are they disabling them? You might want to ask the package maintainers about that.
Now, I reproduced the problem.
So, I rebuilt MLT without disabling MMX and SSE2, and I still reproduce the problem. Morever, the problem only appears with YUV output, not RGB such as wen you are paused in melt or Kdenlive and stepping frame-by-frame. Based on this, since I did not change anything in MLT during this examination, I suspect the change in FFmpeg made the difference. I am not seeing this problem with several other videos I tried in various formats including DV. I am also not seeing this in ffplay, but ffplay prefers yuv420p while MLT has FFmpeg convert everything to yuv422 for MLT's yuv processing routines. I will have to keep looking. Maybe try some different FFmpeg or libswscale versions.

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Dan Dennedy - 2010-03-23

edit: "such as wen you are paused in melt" and using -consumer sdl_preview

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Dan Dennedy - 2010-03-23

More testing.
'ffmpeg -i example.avi -pix_fmt yuv422p example.dv' does not reproduce it.
I disabled all automatic image filters in MLT, and it still occurs. Since it occurs with both SDL and avformat MLT consumers, and not a result of a filter, it must be a bug somewhere in producer_avformat.c, but at this point I have no idea where. strange and frustrating.

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Anonymous - 2010-04-12

Same problem, kdenlive 0.7.7.1, mlt 0.5.2 and mlt-git 20100411, ffmpeg 22511.

1. download http://stargate.gamca.sk/~rejdi/tmp/2010-03-25-105206.ogv
2. create new project in kdenlive
3. add this clip
4. white dots and artefacts appear even in preview and also in final render. Looks like the problem is with black surfaces.

Same problem, kdenlive 0.7.7.1, mlt 0.5.2 and mlt-git 20100411, ffmpeg 22511. 1\. download http://stargate.gamca.sk/~rejdi/tmp/2010-03-25-105206.ogv 2\. create new project in kdenlive 3\. add this clip 4\. white dots and artefacts appear even in preview and also in final render. Looks like the problem is with black surfaces.

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Fabio Varesano - 2010-04-12

@rejdi yep.. I've been able to see the artifacts on your video. Actually it's possible to see them just issueing "melt 2010-03-25-105206.ogv" without using kdenlive.

I'm just an user like you.. I can't help you troubleshooting this bug.. Let's hope developers will work on this soon.. Looks quite a serious bug to me..

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Anonymous - 2010-04-23

I am also seeing this problem.

Issuing "melt <filename>" produces the white noise wherever there is blackness.

Running through ffmpeg or mplayer does not produce the white noise.

Please see the MP4 file extracted from my camera and totally unaltered at: http://www.tekuiti.co.uk/SANY0045.MP4

Version: MLT melt 0.5.4

Let me know what other information you require.

Thank you for your time.

Last edit: Anonymous 2017-02-12

I am also seeing this problem. Issuing "melt <filename>" produces the white noise wherever there is blackness. Running through ffmpeg or mplayer does not produce the white noise. Please see the MP4 file extracted from my camera and totally unaltered at: http://www.tekuiti.co.uk/SANY0045.MP4 Version: MLT melt 0.5.4 Let me know what other information you require. Thank you for your time.

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Dan Dennedy - 2010-04-26

I discovered I only reproduce this when configuring ffmpeg with --enable-runtime-cpudetect.

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Dan Dennedy - 2010-04-26

Fixed in MLT git commit 3d14fb4.

I had to use a different interpolation flag for when using swscale for image/colorspace conversion and not actually scaling.

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Dan Dennedy - 2010-04-26

Here is a note about what runtime-cpudetect does.
http://ffmpeg.arrozcru.org/forum/viewtopic.php?f=1&t=1185

Neither ffmpeg nor melt automatically detect and pass cpu flags. So, when you are using this configure option, you may see degraded performance without additional work. I am not sure how this plays into packaging decisions based on architecture support et al.

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Fabio Varesano - 2010-04-26

Tested with melt from git. Everything seems fixed now. Thanks Dan! Keep on Rocking!

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Thomas Viviano - 2010-06-08

I'm having the same issue. How do you incorporate the fix?

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Dan Dennedy - 2010-06-08

tviviano, you would need to build MLT from source by cloning the public git repo on mltframework.org. How best to do that depends on your distro, but I am not able to provide you any assistance in that matter. I do plan to release the next version by June 20 at the latest.

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Dan Dennedy - 2010-06-20

status: open --> closed
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Dan Dennedy - 2010-06-20

version 0.5.6 released

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