[FFmpeg-devel] [PATCH] Add opaque to avfilter_graph_parse()

Michael Niedermayer michaelni
Fri May 8 13:26:40 CEST 2009

On Fri, May 08, 2009 at 12:52:08PM +0200, Vitor Sessak wrote:
> V??ctor Paesa wrote:
>> Hi,
>> On Sun, April 5, 2009 21:45, Vitor Sessak wrote:
>>> V??ctor Paesa wrote:
>>>> Hi,
>>>> On Sat, March 28, 2009 19:46, V??ctor Paesa wrote:
>>>>> Hi,
>>>>> On Sat, March 28, 2009 17:01, Michael Niedermayer wrote:
>>>>>> On Fri, Mar 27, 2009 at 04:50:43PM +0100, V??ctor Paesa wrote:
>>>>>>> Hi,
>>>>>>> I'd like to add a void *opaque to avfilter_graph_parse(), so that
>>>>>>> it passes it on to avfilter_init_filter(), instead of passing NULL.
>>>>>>> This extension to the API is not used by ffmpeg.c, but I imagine
>>>>>>> other applications may want to use the graph parsing facilities,
>>>>>>> and be happier if it is possible to give some value to opaque
>>>>>>> (even if the same for every filter in graph).
>>>>>> humans write plain/text, computers like text/plain
>>>>>> my mutt is pretty robust in displaying patches with wrong mime types
>>>>>> inline and colored but this one was too much.
>>>>> Sorry, I'm afraid the computer I used to send my patches from didn't
>>>>> had applied this .reg to set the mime types:
>>>>> -------------------------------
>>>>> Windows Registry Editor Version 5.00
>>>>> [HKEY_CLASSES_ROOT\.diff]
>>>>> @="txtfile"
>>>>> "PerceivedType"="diff"
>>>>> "Content Type"="text/x-patch"
>>>>> -------------------------------
>>>>> Here are attached again, as text/x-patch
>>> I'm not against the patch per see, but I'd like someone who followed
>>> lavfi development from the start to explain why an opaque arg is needed.
>>>  From memory, I don't remember anything thats uses it and it begs for
>>> been misused...
>> Lacking a better explanation from the author, I have the feeling that
>> the avfilter pipe is effectively isolated: video in, video out, but no way
>> to report back to the application that there is something interesting in 
>> one
>> particular frame.
>> Imagine a video surveillance application, that detects strangers entering
>> the door. The opaque pointer would contain a callback function,
>> for example.
> Patch ok them, even if I'm not completely happy with the "opaque" concept. 
> Sorry for the delay...

id like to make it clear that this patch is not ok for ffmpeg svn
also id like to repeat that work should be concentrated on moving
libavfilter code from soc svn to ffmpeg svn.
Each addition of code to libavfilter in soc will likely make the
eventual merge MUCH more painfull.
Its all these little changes that get commited with no thought and no
justification, all of that will have to be reviewed and almost all
will have to be reverted before the code could be put in ffmpeg svn.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No human being will ever know the Truth, for even if they happen to say it
by chance, they would not even known they had done so. -- Xenophanes
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