[FFmpeg-devel] [PATCH] [1/??] [2/3] Basic infrastructure

[Vitor Sessak]

Hi

Michael Niedermayer wrote:
> On Sun, Feb 10, 2008 at 11:03:48AM +0100, Vitor Sessak wrote:
>> Hi and thanks for the review
> [...]
>>>>         switch(link->init_state) {
>>>>         case AVLINK_INIT:
>>>>             continue;
>>>>         case AVLINK_STARTINIT:
>>>>             av_log(filter, AV_LOG_ERROR, "circular filter chain detected\n");
>>>>             return -1;
>>>>         case AVLINK_UNINIT:
>>>>             link->init_state = AVLINK_STARTINIT;
>>>>
>>>>             if(avfilter_config_links(link->src))
>>>>                 return -1;
>>>>
>>>>             if(!(config_link = link_spad(link).config_props))
>>>>                 config_link  = avfilter_default_config_output_link;
>>>>             if(config_link(link))
>>>>                 return -1;
>>>>
>>>>             if((config_link = link_dpad(link).config_props))
>>>>             if(config_link(link))
>>>>                 return -1;
>>>>
>>>>             link->init_state = AVLINK_INIT;
>>>>         }
>>>>     }
>>> what does the above mean for filter graphs like:
>>>
>>> ->mix--->duplicate--->
>>>    ^         |
>>>    |         v
>>>     \------delay
>>>
>>> aka an infinite impulse response video filter :)
>>> it looks like it would return -1 for that ...
>> What should be done in these cases? Something like av_log("Circular 
>> video chain, expect trouble\n")?
> 
> Well, id say avfilter should work with circular chains as well. Of course
> not with all, one can easily build ones which would deadlock ...
> Actually most random circular chains would deadlock, but above would not
> as long as the duplicate filter is carefully implemented. That is if
> a request from the delay filter would be satifies with whatever last
> frame the duplicate filter has and never be passed on to the mix filter.

Ok. So I think a warning is more appropriated.

> 
> 
> [...]
> 
>> All the other points I don't mention, agreed and changed. New code in 
>> http://svn.mplayerhq.hu/soc/libavfilter/avfilter.c?content-type=text%2Fplain&view=co 
>> (Diego, nits changed in the soc tree too).
> 
> This is just one file the patch contained more, thus i cant review it and
> you should send patches anyway instead of links to non constant files.
> 

Ok. Attached.

-Vitor
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