[FFmpeg-devel] [PATCH 2/4] API: add AV_PKT_DATA_S12M_TIMECODE to AVPacketSideDataType
lance.lmwang at gmail.com
lance.lmwang at gmail.com
Mon Jun 29 16:37:35 EEST 2020
On Mon, Jun 29, 2020 at 02:06:49PM +0200, Andreas Rheinhardt wrote:
> lance.lmwang at gmail.com:
> > On Mon, Jun 29, 2020 at 04:53:21AM +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 | 8 ++++++++
> >>> libavcodec/version.h | 2 +-
> >>> libavformat/dump.c | 22 ++++++++++++++++++++++
> >>> 6 files changed, 36 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..a4316a7 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 12-1 timecode";
> >>> }
> >>> return NULL;
> >>> }
> >>> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> >>> index a4e50c0..a2bf0cc 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 41485f4..72cb4f7 100644
> >>> --- a/libavcodec/packet.h
> >>> +++ b/libavcodec/packet.h
> >>> @@ -283,6 +283,14 @@ enum AVPacketSideDataType {
> >>> AV_PKT_DATA_DOVI_CONF,
> >>>
> >>> /**
> >>> + * Timecode which conforms to SMPTE ST 12-1. 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.
> >>> + * The timecode format is described in the av_timecode_get_smpte_from_framenum()
> >>> + * function in libavutil/timecode.c.
> >>
> >> The format is documented in a C source file, not a public header? Sure
> >> about that?
> >
> > For AV_PKT_DATA_S12M_TIMECODE use the same format with AV_FRAME_DATA_S12M_TIMECODE, so I copy the
> > comments for AV_FRAME_DATA_S12M_TIMECODE, it's not my comments for it. I think the format is described
> > in "SMPTE ST 12-2:2014" standard document, but it's not free for download.
> >
>
> It's SMPTE ST 12-1:2014 and this standard is currently (until 21 July)
> available for free [1] due to Corona.
oh, it's good to hear it's free due to Corona. I haven't notice it's online.
>
> > What's your suggestion to change?
> >
>
> The best is probably to incorporate the documentation of the format into
> the documentation of av_timecode_get_smpte_from_framenum.
OK, I'll remove the comments for the timecode format.
>
> >>
> >>> + */
> >>> + 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..c5f0bd6 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 +403,23 @@ static void dump_dovi_conf(void *ctx, AVPacketSideData* sd)
> >>> dovi->dv_bl_signal_compatibility_id);
> >>> }
> >>>
> >>> +static void dump_s12m_timecode(void *ctx, AVPacketSideData* sd)
> >>> +{
> >>> + uint32_t *tc = (uint32_t*)sd->data;
> >>> + int m = tc[0] & 3;
> >>> +
> >>> + if (sd->size != sizeof(uint32_t) * 4) {
>
> You already dereferenced tc before this check which might crash if the
> size is actually < sizeof(uint32_t). And why do you only look at the
> lowest two bits of m? Is this designed with future extensions of the
> timecode in mind? But even then one can't simply use the upper 30 bits
> to store something else, because that has not been documented.
> (Moreover, if one allowed extensions, one should allow sd->size to be >=
> sizeof(uint32_t) * 4.)
It's from the comments for the side data, it used to avoid index overflow,
for the array is 4. I'll fix to get the m after the checking.
comments:
where the first uint32_t describes how many (1-3) of the other timecodes are used
I think it's for the timecode SEI define 2bits for the count of used timecomes,
it's not related to SMPTE ST 12-1. vf_showinfo.c have dump AV_FRAME_DATA_S12M_TIMECODE,
I'm following it as format is same, but change m to & 3 for I think it's more simple.
>
> >>> + av_log(ctx, AV_LOG_ERROR, "invalid data");
> >>> + return;
> >>> + }
> >>> +
> >>> + for (int j = 1; j <= m; 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 != m ? ", " : "");
> >>> + }
> >>> +}
> >>> +
>
> - Andreas
>
> [1]: https://www.smpte.org/free-standards-and-publications
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--
Thanks,
Limin Wang
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