[FFmpeg-devel] [PATCH] avdevice/decklink: add option to drop frames till timecode is seen

[Gyan]

On 17-11-2019 10:00 pm, Marton Balint wrote:
>
>> From: Gyan Doshi <ffmpeg at gyani.pro>
>> Date: Mon, 9 Sep 2019 18:33:09 +0530
>> Subject: [PATCH v2] avdevice/decklink: add option to drop frames till 
>> timecode
>>  is seen
>>
>> Option wait_for_tc only takes effect if tc_format is set
>> ---
>>  doc/indevs.texi                 |  8 ++++++++
>>  libavdevice/decklink_common.h   |  1 +
>>  libavdevice/decklink_common_c.h |  1 +
>>  libavdevice/decklink_dec.cpp    | 10 ++++++++++
>>  libavdevice/decklink_dec_c.c    |  1 +
>>  libavdevice/version.h           |  2 +-
>>  6 files changed, 22 insertions(+), 1 deletion(-)
>>
>> diff --git a/doc/indevs.texi b/doc/indevs.texi
>> index 14595774f3..bc791013f2 100644
>> --- a/doc/indevs.texi
>> +++ b/doc/indevs.texi
>> @@ -395,6 +395,14 @@ Either sync could go wrong by 1 frame or in a 
>> rarer case
>>  @option{timestamp_align} seconds.
>>  Defaults to @samp{0}.
>>
>> + at item wait_for_tc (@emph{bool})
>> +Drop frames till a frame with timecode is received. Sometimes serial 
>> timecode
>> +isn't received with the first input frame. If that happens, the 
>> stored stream
>> +timecode will be inaccurate. If this option is set to @option{true}, 
>> input frames
>> +are dropped till a frame with timecode is received.
>> +Option @var{timecode_format} must have been set.
>
> I don't think "must have been" is correct here. Maybe simply write this:
>
> Option @var{timecode_format} must also be specified.
>
>> +Defaults to @option{false}.
>> +
>>  @end table
>>
>>  @subsection Examples
>> diff --git a/libavdevice/decklink_common.h 
>> b/libavdevice/decklink_common.h
>> index 921818ba41..35422a300b 100644
>> --- a/libavdevice/decklink_common.h
>> +++ b/libavdevice/decklink_common.h
>> @@ -149,6 +149,7 @@ struct decklink_ctx {
>>
>>      int channels;
>>      int audio_depth;
>> +    unsigned long tc_seen;    // used with option wait_for_tc
>>  };
>>
>>  typedef enum { DIRECTION_IN, DIRECTION_OUT} decklink_direction_t;
>> diff --git a/libavdevice/decklink_common_c.h 
>> b/libavdevice/decklink_common_c.h
>> index ca85ec2504..b78630b5fc 100644
>> --- a/libavdevice/decklink_common_c.h
>> +++ b/libavdevice/decklink_common_c.h
>> @@ -58,6 +58,7 @@ struct decklink_cctx {
>>      int copyts;
>>      int64_t timestamp_align;
>>      int timing_offset;
>> +    int wait_for_tc;
>>  };
>>
>>  #endif /* AVDEVICE_DECKLINK_COMMON_C_H */
>> diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
>> index 4da9122bff..ab7f28112e 100644
>> --- a/libavdevice/decklink_dec.cpp
>> +++ b/libavdevice/decklink_dec.cpp
>> @@ -784,6 +784,8 @@ HRESULT 
>> decklink_input_callback::VideoInputFrameArrived(
>>                              if (packed_metadata) {
>>                                  if (av_packet_add_side_data(&pkt, 
>> AV_PKT_DATA_STRINGS_METADATA, packed_metadata, metadata_len) < 0)
>> av_freep(&packed_metadata);
>> +                                else if (!ctx->tc_seen)
>> +                                    ctx->tc_seen = ctx->frameCount;
>>                              }
>>                          }
>>                      }
>> @@ -793,6 +795,14 @@ HRESULT 
>> decklink_input_callback::VideoInputFrameArrived(
>>              }
>>          }
>>
>> +        if (ctx->tc_format && cctx->wait_for_tc && !ctx->tc_seen) {
>> +
>> +            av_log(avctx, AV_LOG_WARNING, "No TC detected yet. 
>> wait_for_tc set. Dropping. \n");
>> +            av_log(avctx, AV_LOG_WARNING, "Frame received (#%lu) - "
>> +                        "- Frames dropped %u\n", ctx->frameCount, 
>> ++ctx->dropped);
>> +            return S_OK;
>> +        }
>> +
>>          pkt.pts = get_pkt_pts(videoFrame, audioFrame, wallclock, 
>> abs_wallclock, ctx->video_pts_source, ctx->video_st->time_base, 
>> &initial_video_pts, cctx->copyts);
>>          pkt.dts = pkt.pts;
>>
>> diff --git a/libavdevice/decklink_dec_c.c b/libavdevice/decklink_dec_c.c
>> index 7aceaf934c..99439f91ae 100644
>> --- a/libavdevice/decklink_dec_c.c
>> +++ b/libavdevice/decklink_dec_c.c
>> @@ -85,6 +85,7 @@ static const AVOption options[] = {
>>      { "audio_depth",   "audio bitdepth (16 or 32)", 
>> OFFSET(audio_depth),  AV_OPT_TYPE_INT,   { .i64 = 16}, 16, 32, DEC },
>>      { "decklink_copyts", "copy timestamps, do not remove the initial 
>> offset", OFFSET(copyts), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, DEC },
>>      { "timestamp_align", "capture start time alignment (in 
>> seconds)", OFFSET(timestamp_align), AV_OPT_TYPE_DURATION, { .i64 = 0 
>> }, 0, INT_MAX, DEC },
>> +    { "wait_for_tc",     "drop frames till a frame with timecode is 
>> received. TC format must be set", OFFSET(wait_for_tc), 
>> AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, DEC },
>>      { NULL },
>>  };
>>
>> diff --git a/libavdevice/version.h b/libavdevice/version.h
>> index e3a583d267..68302908cf 100644
>> --- a/libavdevice/version.h
>> +++ b/libavdevice/version.h
>> @@ -29,7 +29,7 @@
>>
>>  #define LIBAVDEVICE_VERSION_MAJOR  58
>>  #define LIBAVDEVICE_VERSION_MINOR   9
>> -#define LIBAVDEVICE_VERSION_MICRO 100
>> +#define LIBAVDEVICE_VERSION_MICRO 101
>>
>>  #define LIBAVDEVICE_VERSION_INT 
>> AV_VERSION_INT(LIBAVDEVICE_VERSION_MAJOR, \
>> LIBAVDEVICE_VERSION_MINOR, \
>> -- 
>> 2.24.0
>
> Otherwise LGTM.

Docs revised and pushed as d831edc387c17c25372ff317715b6d6bce235c13

Thanks,
Gyan