[FFmpeg-devel] [PATCH v6 3/3] avdevice/decklink_dec: export timecode with s12m side data

[Marton Balint]

On Thu, 9 Jul 2020, lance.lmwang at gmail.com wrote:

> On Wed, Jul 08, 2020 at 11:59:17PM +0200, Marton Balint wrote:
>> 
>> 
>> On Wed, 8 Jul 2020, lance.lmwang at gmail.com wrote:
>> 
>> > On Wed, Jul 01, 2020 at 09:39:58PM +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>
>> > > ---
>> > >  libavdevice/decklink_dec.cpp | 16 ++++++++++++++++
>> > >  1 file changed, 16 insertions(+)
>> > > 
>> > > diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
>> > > index 82106aa..0fc1489 100644
>> > > --- a/libavdevice/decklink_dec.cpp
>> > > +++ b/libavdevice/decklink_dec.cpp
>> > > @@ -41,6 +41,7 @@ extern "C" {
>> > >  #include "libavutil/imgutils.h"
>> > >  #include "libavutil/intreadwrite.h"
>> > >  #include "libavutil/time.h"
>> > > +#include "libavutil/timecode.h"
>> > >  #include "libavutil/mathematics.h"
>> > >  #include "libavutil/reverse.h"
>> > >  #include "avdevice.h"
>> > > @@ -778,6 +779,21 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
>> > >                          AVDictionary* metadata_dict = NULL;
>> > >                          int metadata_len;
>> > >                          uint8_t* packed_metadata;
>> > > +                        AVTimecode tcr;
>> > > +                        uint32_t tc_data;
>> > > +                        uint8_t *sd;
>> > > +                        int size = sizeof(uint32_t) * 4;
>> 
>> You can push some of these initializers into the blocks in which they are
>> used.
>
> Sure, will fix it.
>
>> 
>> > > +
>> > > +                        if (av_timecode_init_from_string(&tcr, ctx->video_st->r_frame_rate, tc, ctx) >= 0) {
>> > > +                            if ((tc_data = av_timecode_get_smpte_from_framenum(&tcr, 0)) > 0) {
>> 
>> av_timecode_get_smpte_from_framenum() always succeeds, so this check is
>> wrong.
>
> OK, will fix it.
>
>> 
>> Also in theory you could query the color framing flag from the decklink api.
>
> av_timecode_get_smpte_from_framenum() assume the Color Frame flag is zero
> always, and the conversion from frame to string didn't support the color frame
> flag also, so even we set the flag, it's not used still.

It is a matter of setting a single bit of tc_data, you don't need to add 
API for it.

> Do you insist that this version must support this feature?

No, but if the DeckLink API supports it, and the side data supports it 
then why not? It should be no more than 2 lines of additional code:

unsigned color_flag = !!(timecode->GetFlags() & bmdTimecodeColorFrame);

...

tc_data |= color_flag << 31;

Or am I missing something?

Regards,
Marton

>
>> 
>> Regards,
>> Marton
>> 
>> > > +                                sd = av_packet_new_side_data(&pkt, AV_PKT_DATA_S12M_TIMECODE, size);
>> > > +                                if (sd) {
>> > > +                                    AV_WL32(sd, 1); // one TC ;
>> > > +                                    AV_WL32(sd + 4, tc_data); // TC;
>> > > +                                }
>> > > +                            }
>> > > +                        }
>> > > +
>> > >                          if (av_dict_set(&metadata_dict, "timecode", tc, AV_DICT_DONT_STRDUP_VAL) >= 0) {
>> > >                              packed_metadata = av_packet_pack_dictionary(metadata_dict, &metadata_len);
>> > >                              av_dict_free(&metadata_dict);
>> > > -- 
>> > > 1.8.3.1
>> > > 
>> > 
>> > Marton, please help to review and give comments.
>> > 
>> > -- 
>> > Thanks,
>> > Limin Wang
>> > _______________________________________________
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>
> -- 
> Thanks,
> Limin Wang
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