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Bug 793463 - avvidedec: gstlibav video decoder does not unmap the output frame
avvidedec: gstlibav video decoder does not unmap the output frame
Status: RESOLVED DUPLICATE of bug 740222
Product: GStreamer
Classification: Platform
Component: gst-libav
1.13.x
Other Linux
: Normal major
: git master
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2018-02-14 18:07 UTC by Vikram Fugro
Modified: 2018-02-14 18:45 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
Proposed patch to unmap the frame (1.02 KB, patch)
2018-02-14 18:12 UTC, Vikram Fugro 		rejected Details | Review

Description Vikram Fugro 2018-02-14 18:07:22 UTC 
gstlibav video decoder does not call unmap on the output frame, just before finish_frame(). This leads to the video-frame buffer having more than 1 ref-count. As a result, (since it is now non-writable i.e ref-count > 1), there is always an unnecessary frame-copy step executed just before the output of the decoder (i.e before pushing it downstream)
Comment 1 Vikram Fugro 2018-02-14 18:12:49 UTC 
Created attachment 368350 [details] [review]
Proposed patch to unmap the frame
Comment 2 Tim-Philipp Müller 2018-02-14 18:13:44 UTC 
I'm fairly sure there is an existing bug about that.
Comment 3 Vikram Fugro 2018-02-14 18:29:16 UTC 
Yes, Likely https://bugzilla.gnome.org/show_bug.cgi?id=790087
Comment 4 Nicolas Dufresne (ndufresne) 2018-02-14 18:43:06 UTC 
Nop, this one.

*** This bug has been marked as a duplicate of bug 740222 ***
Comment 5 Nicolas Dufresne (ndufresne) 2018-02-14 18:45:27 UTC 
Review of attachment 368350 [details] [review]:

This patch is not really safe, since the frame may still be read by ffmpeg for later frame construction. The proposal is to implement a remap mechanism, so we can make it read-only before pushing. This is of course specific to direct rendering mode, which need to be ported to a new FFMPEG API, hence all this may be just legacy, to be confirmed. Note that we do unmap the frame, but later on, generally upon next decoded frame.