[vlc-devel] [PATCH v3 3/3] codec/mmal: Add mmal based decoder plugin

Julian Scheel julian at jusst.de
Wed Apr 16 13:16:49 CEST 2014

Am 10.04.2014 22:08, schrieb Rémi Denis-Courmont:
> Le jeudi 10 avril 2014, 12:32:43 Jean-Baptiste Kempf a écrit :
>> On 10 Apr, Julian Scheel wrote :
>>> +#define MMAL_ZEROCOPY_NAME "mmal-zerocopy"
>>> +#define MMAL_ZEROCOPY_TEXT N_("Decode frames directly into RPI VideoCore
>>> instead of host memory.") +#define MMAL_ZEROCOPY_LONGTEXT N_("Decode
>>> frames directly into RPI VideoCore instead of host memory. This option
>>> must only be used with the MMAL video output plugin.")
>> Can't it be autodetected? Aka, if no correct vout, fallback to
>> non-zerocopy mode?
> Of course it can. VDPAU has hit and solved the same problem.

How could it?
Afaict the vdpau decoder always outputs frames in the vdpau internal 
fake format. In case the vout can not render this a video_filter that 
converts from vdpau fake fmt into raw video is instantiated. While this 
is possible with VDPAU we cannot do it with MMAL as of now as there is 
no mmal component which could be used to implement such a filter.
It might be possible soon though... RPi guys are working on exposing the 
image_fx modules, where a copy module is availabe which might help.

As of now to switch between opaque and non-opaque mode we have to set he 
mode on instantiation of the decoder which happens before the vout in 
instantiated. So at that point we cannot detect what formats will be 
supported by the vout.
So as of now I don't see an option to autodetect this.

Any objections?


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