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Bug 733750 - v4l2object: query minimum required buffers for output
v4l2object: query minimum required buffers for output
Status: RESOLVED FIXED
Product: GStreamer
Classification: Platform
Component: gst-plugins-good
git master
Other Linux
: Normal enhancement
: 1.5.1
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2014-07-25 17:09 UTC by Aurélien Zanelli
Modified: 2014-07-25 17:50 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
v4l2object: query minimum required buffers for output (1.49 KB, patch)
2014-07-25 17:09 UTC, Aurélien Zanelli 		committed Details | Review

Description Aurélien Zanelli 2014-07-25 17:09:54 UTC 
Created attachment 281714 [details] [review]
v4l2object: query minimum required buffers for output

As suggested by Nicolas, V4L2 devices could expose a minimum buffers count through the CTRL ioctl. So instead of blindly propose a pool with default value, we may ask the driver first.

I attached a patch which basically do this in gst_v4l2_object_propose_allocation(). 

But I don't found any device using this control, so for test, I just modify my v4l2 drivers.
Comment 1 Nicolas Dufresne (ndufresne) 2014-07-25 17:18:52 UTC 
Review of attachment 281714 [details] [review]:

Looks good. (I'm merging it now)
Comment 2 Nicolas Dufresne (ndufresne) 2014-07-25 17:50:08 UTC 
Comment on attachment 281714 [details] [review]
v4l2object: query minimum required buffers for output

commit 010272a796325d3b9a94b5dcf887706cd2524b27
Author: Aurélien Zanelli <aurelien.zanelli@parrot.com>
Date:   Fri Jul 25 17:42:20 2014 +0200

    v4l2object: query minimum required buffers for output
    
    Some v4l2 devices could require a minimum buffers different from default
    values. Rather than blindly propose a pool with min-buffers set to the
    default value, it ask the device using control ioctl.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=733750
Comment 3 Nicolas Dufresne (ndufresne) 2014-07-25 17:50:58 UTC 
I don't think it's needed to backport, as for now no driver implements this correctly. Will bee needed by the decoder eventually, but that will only make it for 1.6.