[FFmpeg-devel] [PATCH] Re: How can I determine color_range from a filter?

[Larry Robinson]

So here's the easy part, adding the new properties to AVFilterLink.
Let me know if this is inconsistent with style, architecture, etc.

Now - how to fill them:
It looks like configure_filters(...) in ffmpeg.c starts the filter chain 
on line 364 by calling avfilter_graph_create_filter(&ist...).  I propose 
to do the following:

1) Create a new data structure, located in cmdutils.h:
     typedef struct AVVolatileVideoProperties
     {
         enum AVColorPrimaries color_primaries;
         enum AVColorTransferCharacteristic color_trc;
         enum AVColorSpace colorspace;
         enum AVColorRange color_range;
         AVChromaLocation chroma_sample_location;
     } AVVolatileVideoProperties;

NOTE:
If I do this, cmdutils.h will have to be included after avcodec.h, 
because that's where AVColorPrimaries, etc. are declared.
The second option is to  #include avcodec.h  in cmdutils.h - this will 
prevent breaking code that includes cmdutils but not avcodec.
The last option is to declare the structure in both ffmpeg.c and 
ffplay.c and keep it out of cmdutils.h altogether.

Is there any guidance to help me make the decision?

2) Add a new function:  set_volatile_video_properties( AVCodecContext * 
ctx )  to {cmdutils.h, cmdutils.c}
     which will copy the values into the AVVolatileVideoProperties 
structure.

The issues and options noted in (1) apply here also.  Guidance would be 
appreciated.

3) Add an additional parameter to avfilter_graph_create_filter, i.e.

int avfilter_graph_create_filter(AVFilterContext **filt_ctx, AVFilter *filt,
                                  const char *name, const char *args, 
void *opaque,
                                  AVFilterGraph *graph_ctx, 
AVVolatileVideoProperties *vvp);

If vvp is not NULL, the properties in vvp will be copied to the 
AVFilterLink.

4) The new properties will need to be propagated along the filter chain 
(I'll figure out how to do this), and ultimately used by encoders 
(beyond my expertise).



On 1/6/2011 6:28 PM, Michael Niedermayer wrote:
> On Thu, Jan 06, 2011 at 04:06:33PM -0800, Larry Robinson wrote:
>> Let me know what the (few others) are and I will try to add them :-) .
>      /**
>       * Chromaticity coordinates of the source primaries.
>       * - encoding: Set by user
>       * - decoding: Set by libavcodec
>       */
>      enum AVColorPrimaries color_primaries;
>
>      /**
>       * Color Transfer Characteristic.
>       * - encoding: Set by user
>       * - decoding: Set by libavcodec
>       */
>      enum AVColorTransferCharacteristic color_trc;
>
>      /**
>       * YUV colorspace type.
>       * - encoding: Set by user
>       * - decoding: Set by libavcodec
>       */
>      enum AVColorSpace colorspace;
>
>      /**
>       * MPEG vs JPEG YUV range.
>       * - encoding: Set by user
>       * - decoding: Set by libavcodec
>       */
>      enum AVColorRange color_range;
>
>      /**
>       * This defines the location of chroma samples.
>       * - encoding: Set by user
>       * - decoding: Set by libavcodec
>       */
>      enum AVChromaLocation chroma_sample_location;
>
>
> [...]
>
>
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