[FFmpeg-devel] [PATCH v3 1/2] API: add AV_PKT_DATA_S12M_TIMECODE to AVPacketSideDataType

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Mon Jun 29 19:18:23 EEST 2020


lance.lmwang at gmail.com:
> On Mon, Jun 29, 2020 at 05:35:58PM +0200, Andreas Rheinhardt wrote:
>> lance.lmwang at gmail.com:
>>> From: Limin Wang <lance.lmwang at gmail.com>
>>>
>>> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
>>> ---
>>>  doc/APIchanges        |  3 +++
>>>  libavcodec/avpacket.c |  1 +
>>>  libavcodec/decode.c   |  1 +
>>>  libavcodec/packet.h   |  6 ++++++
>>>  libavcodec/version.h  |  2 +-
>>>  libavformat/dump.c    | 21 +++++++++++++++++++++
>>>  6 files changed, 33 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/doc/APIchanges b/doc/APIchanges
>>> index 1d6cc36..7cad7fa 100644
>>> --- a/doc/APIchanges
>>> +++ b/doc/APIchanges
>>> @@ -15,6 +15,9 @@ libavutil:     2017-10-21
>>>  
>>>  API changes, most recent first:
>>>  
>>> +2020-06-xx - xxxxxxxxxx - lavc 58.94.100 - packet.h
>>> +  Add AV_PKT_DATA_S12M_TIMECODE.
>>> +
>>>  2020-06-12 - b09fb030c1 - lavu 56.55.100 - pixdesc.h
>>>    Add AV_PIX_FMT_X2RGB10.
>>>  
>>> diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
>>> index dce26cb..24e2a74 100644
>>> --- a/libavcodec/avpacket.c
>>> +++ b/libavcodec/avpacket.c
>>> @@ -400,6 +400,7 @@ const char *av_packet_side_data_name(enum AVPacketSideDataType type)
>>>      case AV_PKT_DATA_PRFT:                       return "Producer Reference Time";
>>>      case AV_PKT_DATA_ICC_PROFILE:                return "ICC Profile";
>>>      case AV_PKT_DATA_DOVI_CONF:                  return "DOVI configuration record";
>>> +    case AV_PKT_DATA_S12M_TIMECODE:              return "SMPTE ST 12-1:2014 timecode";
>>>      }
>>>      return NULL;
>>>  }
>>> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
>>> index de9c079..f2244fc 100644
>>> --- a/libavcodec/decode.c
>>> +++ b/libavcodec/decode.c
>>> @@ -1699,6 +1699,7 @@ int ff_decode_frame_props(AVCodecContext *avctx, AVFrame *frame)
>>>          { AV_PKT_DATA_CONTENT_LIGHT_LEVEL,        AV_FRAME_DATA_CONTENT_LIGHT_LEVEL },
>>>          { AV_PKT_DATA_A53_CC,                     AV_FRAME_DATA_A53_CC },
>>>          { AV_PKT_DATA_ICC_PROFILE,                AV_FRAME_DATA_ICC_PROFILE },
>>> +        { AV_PKT_DATA_S12M_TIMECODE,              AV_FRAME_DATA_S12M_TIMECODE },
>>>      };
>>>  
>>>      if (pkt) {
>>> diff --git a/libavcodec/packet.h b/libavcodec/packet.h
>>> index 96f237f..d84aaaa 100644
>>> --- a/libavcodec/packet.h
>>> +++ b/libavcodec/packet.h
>>> @@ -283,6 +283,12 @@ enum AVPacketSideDataType {
>>>      AV_PKT_DATA_DOVI_CONF,
>>>  
>>>      /**
>>> +     * Timecode which conforms to SMPTE ST 12-1:2014. The data is an array of 4 uint32_t
>>> +     * where the first uint32_t describes how many (1-3) of the other timecodes are used.
>>> +     */
>>
>> You should move the doc to timecode.h first in a separate patch and then
>> reference the documentation here.
> 
> I'm not native English, so it's difficult for me to describe the format of timecode in comments clearly.
> As it's defined in SMPTE ST 12-1:2014, so I think it's enough as it says conforms to SMPTE ST 12-1:2014
> at beginning. 
> 

Could you please point me to the part of SMPTE ST 12-1:2014 that
describes the format that we use here? Because AFAIK SMPTE ST 12-1:2014
just defines what fields a SMPTE ST 12-1 message has (and what
semantics), but leaves the rest (the actual framing) to other standards:

"The actual transport of the codewords for digital systems varies
significantly from the transport methods defined for analog systems, and
is defined in the associated document, SMPTE ST 12-2."

E.g. RTP uses a different framing (see RFC 5484); obviously every
framing method used for transport must prescribe endianness of not
depend upon endianness; yet our method does. (Isn't this actually a
problem for fate-tests because framecrc calculates checksums for side date?)

>>
>>> +    AV_PKT_DATA_S12M_TIMECODE,
>>> +
>>> +    /**
>>>       * The number of side data types.
>>>       * This is not part of the public API/ABI in the sense that it may
>>>       * change when new side data types are added.
>>> diff --git a/libavcodec/version.h b/libavcodec/version.h
>>> index 0359302..482cc6d 100644
>>> --- a/libavcodec/version.h
>>> +++ b/libavcodec/version.h
>>> @@ -28,7 +28,7 @@
>>>  #include "libavutil/version.h"
>>>  
>>>  #define LIBAVCODEC_VERSION_MAJOR  58
>>> -#define LIBAVCODEC_VERSION_MINOR  93
>>> +#define LIBAVCODEC_VERSION_MINOR  94
>>>  #define LIBAVCODEC_VERSION_MICRO 100
>>>  
>>>  #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
>>> diff --git a/libavformat/dump.c b/libavformat/dump.c
>>> index 117c681..0f64c4f 100644
>>> --- a/libavformat/dump.c
>>> +++ b/libavformat/dump.c
>>> @@ -34,6 +34,7 @@
>>>  #include "libavutil/replaygain.h"
>>>  #include "libavutil/spherical.h"
>>>  #include "libavutil/stereo3d.h"
>>> +#include "libavutil/timecode.h"
>>>  
>>>  #include "avformat.h"
>>>  
>>> @@ -402,6 +403,22 @@ static void dump_dovi_conf(void *ctx, AVPacketSideData* sd)
>>>             dovi->dv_bl_signal_compatibility_id);
>>>  }
>>>  
>>> +static void dump_s12m_timecode(void *ctx, AVPacketSideData* sd)
>>
>> * belongs to the variable, not the type.
>>
>>> +{
>>> +    uint32_t *tc = (uint32_t*)sd->data;
>>> +
>>> +    if ((sd->size != sizeof(uint32_t) * 4) || (tc[0] > 3)) {
>>> +        av_log(ctx, AV_LOG_ERROR, "invalid data\n");
>>> +        return;
>>> +    }
>>> +
>>> +    for (int j = 1; j <= tc[0]; j++) {
>>> +        char tcbuf[AV_TIMECODE_STR_SIZE];
>>> +        av_timecode_make_smpte_tc_string(tcbuf, tc[j], 0);
>>> +        av_log(ctx, AV_LOG_INFO, "timecode - %s%s", tcbuf, j != tc[0] ? ", " : "");
>>> +    }
>>> +}
>>> +
>>>  static void dump_sidedata(void *ctx, AVStream *st, const char *indent)
>>>  {
>>>      int i;
>>> @@ -468,6 +485,10 @@ static void dump_sidedata(void *ctx, AVStream *st, const char *indent)
>>>              av_log(ctx, AV_LOG_INFO, "DOVI configuration record: ");
>>>              dump_dovi_conf(ctx, &sd);
>>>              break;
>>> +        case AV_PKT_DATA_S12M_TIMECODE:
>>> +            av_log(ctx, AV_LOG_INFO, "SMPTE ST 12-1:2014: ");
>>> +            dump_s12m_timecode(ctx, &sd);
>>> +            break;
>>>          default:
>>>              av_log(ctx, AV_LOG_INFO,
>>>                     "unknown side data type %d (%d bytes)", sd.type, sd.size);
>>>
>>


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