[FFmpeg-devel] [PATCH 1/3] avformat/mxfenc: Allow overriding numerical color_siting value.

[Michael Niedermayer]

On Tue, Aug 29, 2017 at 12:02:18PM +0200, wm4 wrote:
> On Tue, 29 Aug 2017 11:59:05 +0200
> Michael Niedermayer <michael at niedermayer.cc> wrote:
> 
> > On Tue, Aug 29, 2017 at 11:02:32AM +0200, wm4 wrote:
> > > On Tue, 29 Aug 2017 02:13:19 +0200
> > > Michael Niedermayer <michael at niedermayer.cc> wrote:
> > >   
> > > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > > ---
> > > >  libavformat/mxfenc.c | 7 ++++++-
> > > >  1 file changed, 6 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/libavformat/mxfenc.c b/libavformat/mxfenc.c
> > > > index 12fc9abbc6..ccfa0d6341 100644
> > > > --- a/libavformat/mxfenc.c
> > > > +++ b/libavformat/mxfenc.c
> > > > @@ -322,6 +322,7 @@ typedef struct MXFContext {
> > > >      uint8_t umid[16];        ///< unique material identifier
> > > >      int channel_count;
> > > >      int signal_standard;
> > > > +    int color_siting;
> > > >      uint32_t tagged_value_count;
> > > >      AVRational audio_edit_rate;
> > > >      int store_user_comments;
> > > > @@ -2085,6 +2086,8 @@ static int mxf_write_header(AVFormatContext *s)
> > > >              case AVCHROMA_LOC_TOP:     sc->color_siting = 1; break;
> > > >              case AVCHROMA_LOC_CENTER:  sc->color_siting = 3; break;
> > > >              }
> > > > +            if (mxf->color_siting >= 0)
> > > > +                sc->color_siting = mxf->color_siting;
> > > >  
> > > >              mxf->timecode_base = (tbc.den + tbc.num/2) / tbc.num;
> > > >              spf = ff_mxf_get_samples_per_frame(s, tbc);
> > > > @@ -2668,7 +2671,9 @@ static int mxf_interleave(AVFormatContext *s, AVPacket *out, AVPacket *pkt, int
> > > >      { "smpte349m", "SMPTE 349M (1485 Mbps mappings)",\
> > > >        0, AV_OPT_TYPE_CONST, {.i64 = 6}, -1, 7, AV_OPT_FLAG_ENCODING_PARAM, "signal_standard"},\
> > > >      { "smpte428", "SMPTE 428-1 DCDM",\
> > > > -      0, AV_OPT_TYPE_CONST, {.i64 = 7}, -1, 7, AV_OPT_FLAG_ENCODING_PARAM, "signal_standard"},
> > > > +      0, AV_OPT_TYPE_CONST, {.i64 = 7}, -1, 7, AV_OPT_FLAG_ENCODING_PARAM, "signal_standard"},\
> > > > +    { "color_siting", "Force/set Color siting",\
> > > > +      offsetof(MXFContext, color_siting), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 7, AV_OPT_FLAG_ENCODING_PARAM, "color_siting"},\
> > > >  
> > > >  
> > > >    
> > > 
> > > What an absurd patch. This should be done by generic code overriding
> > > the chroma_location field on AVFrames sent to the encoders. We don't
> > > need inconsistent private options for an inconsistent set of encoders
> > > to override generic parameters in an inconsistent way. What's even the
> > > point?  
> > 
> > The point of this change is to be able to set any color siting value.
> > MXF has some redundant values. The fields from AVFrame are not enough
> > to choose this unless we want MXF specific information in AVFrames
> > 
> > [...]
> 
> You probably want to use some specialized MXF tool then.

It should be possible to generate mxf files with just one tool not 2.
In fact this change is for someone else not me, i probably wont be
using it much.

Do you object to this patch ?
If you veto it, i will not apply it of course.

if not i will apply it with the lines reordered to avoid the \ issue
raised by paul
as FFmpeg is intended to be a universal multimedia tool and requiring
a 2nd tool is cumbersome.

Thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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