[vlc-devel] Implementing crop using the current vout API

Felix Paul Kühne fkuehne.videolan at googlemail.com
Sat Mar 10 19:02:49 CET 2012

Hello guys,

as some of you might have seen on the forums or trac, cropping the video isn't supported in the 2.0.0 release of VLC for the Mac, mostly because I didn't know prior to release that the video output module needs to implement the functionality, since it isn't provided by the core (yet? at least, I get a "TODO FIXME" error message related to core crop when blocking crop events in the vout).

Anyway, based upon the x11 vout, I cooked up a patch which provides the needed functionality quite nicely:


However, this code does only work for a certain set of chroma formats and video sizes [1]. Otherwise, I get repeatable crashes in swscale [2], the OS graphics driver [3] and the core's video filter functionality [4].

Additionally, when changing the crop border, my debug log is spammed with error messages from the core about the use of "ThreadExecuteCropBorder". So I guess, this isn't the intended way to change the crop border? Or is this just a debug left over?
Furthermore, there are artifacts when cropping 10bit content. [5]

It would be really cool to get some advice on this issue, since I'm a bit stuck at the moment.



[1] basically, the only working samples I got supporting all crop formats are H.264 (baseline profile) videos with Planar 4:2:0 YUV with a 16:9 AR. A native AR of 16:10 leads to the mentioned artifacts or crashes.
[2] http://pastie.org/3565494
[3] http://pastie.org/3565509
[4] http://pastie.org/3565537
[5] http://cl.ly/3P3G3a1P3U431K3d212K and http://cl.ly/2E3Z1d382s163n3i2B3u

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