[FFmpeg-soc] libavfilter audio work - qualification task

[S.N. Hemanth Meenakshisundaram]

On 04/18/2010 05:10 PM, Stefano Sabatini wrote:
> On date Sunday 2010-04-18 16:10:35 -0700, S.N. Hemanth Meenakshisundaram encoded:
>    
>> On 04/13/2010 12:05 AM, Stefano Sabatini wrote:
>>      
>>> On date Monday 2010-04-12 22:52:44 -0700, S.N. Hemanth Meenakshisundaram encoded:
>>> [...]
>>>        
>>>> I had one (dumb?) question about yadif :
>>>>
>>>> Since the PicRef structure in libavfilter has no 'fields' member,
>>>> how do I find out if the image data in the buffer is
>>>> MP_IMGFIELD_ORDERED, MP_IMGFIELD_TOP_FIRST etc. Is it indicated in
>>>> the PixelFormat?
>>>>          
>>> Ehm no, I believe we need to add it to the AVFilterPicRef struct.
>>>
>>>        
>> Hi,
>>
>> I have a couple more questions :
>>
>> 1. It looks like we output two frames for every input frame/field if
>> mode is 1 or 3, else we output a single frame. Is this right?
>>      
> > From the manual page of mplayer:
>
>         yadif=[mode[:field_dominance]]
>                Yet another deinterlacing filter
>                   <mode>
>                        0: Output 1 frame for each frame.
>                        1: Output 1 frame for each field.
>                        2: Like 0 but skips spatial interlacing check.
>                        3: Like 1 but skips spatial interlacing check.
>
> So yes you look right.
>
>    
>> 2. The mplayer code has a correct_pts variable that seems to allow
>> doubling of frame rate. Here is it safe to assume this is always
>> allowed/true?
>>      
> I suppose so, that will also depend on the mode, from what I can
> understand you'll need to duplicate the frame rate only with mode 1/3,
> this will be done manipulating the output pts.
>
>    
>> 3. If I add a 'fields' member to AVFilterPicRef struct, how do I
>> make sure it will be set to the right value (i.e. TOP_FIRST etc)?
>>      
> It is a problem of the calling application to set this, for example an
> application requests a picref with avfilter_get_video_buffer() and
> sets the field accordingly. In the case of ffmpeg.c/ffplay.c this
> depends on the options set in the codec context or by the user
> (e.g. -top_field 1).
>
>    
>> Thanks
>>      
> Regards.
>    
Thank you. Attached is an initial vf_yadif.c - I have only compiled it 
yet and will start testing it shortly. A couple of questions :

1. I wasn't sure how to modify the header since we wanted to keep yadif 
under the GPL while the rest of FFmpeg is under the LGPL.

2. Is the PixelFormat YUV420P equivalent to YV12 or IYUV/I420. The 
description for YUV420P doesn't seem to say if the 2nd and 3rd planes 
are VU or UV. Where can I find the other PixelFormat equivalent.

Regards,


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