AVFrameWrapper falling out of scope before being freed by avcodec

[totaam]

Issue migrated from trac ticket # 398

component: client | priority: critical | resolution: wontfix | keywords: win32

2013-08-01 09:30:08: antoine created the issue

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As can be seen in #362#comment:6, it seems to be possible for a framewrapper to fall out of scope before it has been freed by avcodec.

This is caused by the buffer management code in #350 (r3976)

Please post log with XPRA_AVCODEC_DEBUG=1 for just 2 or 3 frames as per #350#comment:6.

Do you need to use a specific application to trigger those warnings?
Can you reproduce with a simple xterm?
Did you apply any patches when you built the installer for win32?
What version of ffmpeg did you build against?
I've uploaded a new win32 beta - please compare this with your build.

[totaam]

2013-08-01 17:30:26: antoine edited the issue description

[totaam]

2013-08-02 09:05:44: smo commented

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Built new x264 and ffmpeg

ftp://ftp.videolan.org/pub/x264/snapshots/x264-snapshot-20130801-2245-stable.tar.bz2
http://www.ffmpeg.org/releases/ffmpeg-1.2.2.tar.bz2

No more AVFrameWrapper messages after packaging a new installer with r4041

[totaam]

2013-08-02 09:07:27: totaam changed status from new to closed

[totaam]

2013-08-02 09:07:27: totaam changed resolution from ** to invalid

[totaam]

2013-08-02 09:07:27: totaam commented

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Great - closing as INVALID, must have been an old version of ffmpeg.

(may cause problems for us on some versions of libav/ffmpeg though..)

[totaam]

2013-08-07 11:00:50: ahuillet commented

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I see the problem with latest Archlinux (ffmpeg 2.0).

[totaam]

2013-08-07 11:01:54: totaam changed status from closed to reopened

[totaam]

2013-08-07 11:01:54: totaam changed resolution from invalid to **

[totaam]

2013-08-07 11:01:54: totaam commented

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Please post some output with XPRA_AVCODEC_DEBUG=1

[totaam]

2013-08-07 11:02:04: totaam changed status from reopened to new

[totaam]

2013-08-07 11:02:04: totaam changed owner from SmO to ahuillet

[totaam]

2013-08-07 14:29:16: ahuillet commented

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Edit by totaam: large comment moved to out-of-scope-debug.log attachment.
[[BR]]
Is that enough?

[totaam]

2013-08-07 15:54:02: totaam commented

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It seems to me like this happens when a window is destroyed, or resized, right? Is this with ffmpeg 2.x?
Can I get a bit more context?

[[BR]]

What I think is happening is that when we clean the decoder context, we clone the pixel data which calls xpra_free(), then when we call avcodec_close it calls av_free() and all is well. We lose all the references to the wrappers, they get garbage collected and we check that it is safe to free the reference (as the buffer should already have been freed by then).
That's on my version of ffmpeg... (Linux, OSX and win32)

[[BR]]
But here, I am not seeing a single av_free at all. It looks like the avcodec_release_buffer function is never called.

[totaam]

2013-08-07 16:15:42: ahuillet commented

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This is with ffmpeg 2.0. I did not check if it happened when a window was destroyed or resized, but I think it is a reasonable assumption - I remember I got my terminal flooded with those messages when I resized a xterm from very small to very big.

[totaam]

2013-08-10 06:31:00: totaam commented

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I am closing this ticket after testing on most supported platforms with ffmpeg 1.2.x. If this problem re-occurs with a supported version of ffmpeg, then we can re-open this ticket.

Support for ffmpeg 2.0 is now moved to #415

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Note: the buffer support change was messy (esp compat for older versions - patches, etc):

• r4124 double free bug
• r4123, r4102: patch offsets
• r4122: avoid warning
• r4101: limited pix formats compat
• r4100, r4099, r4098: better error reporting

[totaam]

2013-08-10 06:41:09: totaam changed status from new to closed

[totaam]

2013-08-10 06:41:09: totaam changed resolution from ** to wontfix

[totaam]

2013-08-10 06:41:09: totaam commented

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(actually closing it)

[totaam]

2013-12-03 06:22:12: totaam uploaded file out-of-scope-debug.log (24.6 KiB)

log sample for comment:7 (moving large waste of space comment to an attachment)