[FFmpeg-devel] [PATCH v1 3/5] avfilter/vf_showinfo: display user data unregistered message

[Limin Wang]

On Wed, Dec 18, 2019 at 11:22:05PM +0100, Michael Niedermayer wrote:
> On Wed, Dec 18, 2019 at 08:55:04AM +0800, Limin Wang wrote:
> > On Tue, Dec 17, 2019 at 10:22:47PM +0100, Michael Niedermayer wrote:
> > > On Tue, Dec 17, 2019 at 06:22:15PM +0800, lance.lmwang at gmail.com wrote:
> > > > From: Limin Wang <lance.lmwang at gmail.com>
> > > > 
> > > > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > > > ---
> > > >  libavfilter/vf_showinfo.c | 20 ++++++++++++++++++++
> > > >  1 file changed, 20 insertions(+)
> > > > 
> > > > diff --git a/libavfilter/vf_showinfo.c b/libavfilter/vf_showinfo.c
> > > > index 31f6b32aa4..0d227983c2 100644
> > > > --- a/libavfilter/vf_showinfo.c
> > > > +++ b/libavfilter/vf_showinfo.c
> > > > @@ -169,6 +169,23 @@ static void dump_content_light_metadata(AVFilterContext *ctx, AVFrameSideData *s
> > > >             metadata->MaxCLL, metadata->MaxFALL);
> > > >  }
> > > >  
> > > > +static void dump_user_data_unregistered_metadata(AVFilterContext *ctx, AVFrameSideData *sd)
> > > > +{
> > > > +    const int uuid_size = 16;
> > > > +
> > > > +    if (sd->size < uuid_size) {
> > > > +        av_log(ctx, AV_LOG_ERROR, "invalid data");
> > > > +        return;
> > > > +    }
> > > 
> > > The need for a UUID (of 16bytes) is not described in the text describing 
> > > this side data type
> > By the specs:
> > user_data_unregistered( payloadSize ) { C Descriptor
> > uuid_iso_iec_11578                      5 u(128)
> > for( i = 16; i < payloadSize; i++ )
> > user_data_payload_byte                  5 b(8)
> > }
> 
> ive been inprecise
> what i have meant was this:
> @@ -179,6 +179,13 @@ enum AVFrameSideDataType {
>       * array element is implied by AVFrameSideData.size / AVRegionOfInterest.self_size.
>       */                                                                                
>      AV_FRAME_DATA_REGIONS_OF_INTEREST,
> +
> +    /**
> +     * User data unregistered metadata associated with a video frame.
> +     * This user data payload is stored as uint8_t in AVFrameSideData.data.
> +     * The number of bytes of user data is AVFrameSideData.size.

Got it, I'll add the one more line description for the need for the UUID.
        * The user data consists of 16 bytes UUID and the other parts are 
        * real user data .

> +     */
> +    AV_FRAME_DATA_USER_DATA_UNREGISTERED,
>  };
> 
>  enum AVActiveFormatDescription {
> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> Rewriting code that is poorly written but fully understood is good.
> Rewriting code that one doesnt understand is a sign that one is less smart
> then the original author, trying to rewrite it will not make it better.



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