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

[Ví­ctor Paesa]

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.

Regards,
V?ctor