lance.lmw...@gmail.com (12020-06-30):
> From: Limin Wang <lance.lmw...@gmail.com>
>
> AV_FRAME_DATA_S12M_TIMECODE is public API, so user need to know its format
> by the API header instead of reading the code.
>
> Signed-off-by: Limin Wang <lance.lmw...@gmail.com>
> ---
> libavutil/frame.h | 4 ++--
> libavutil/timecode.h | 16 +++++++++++++++-
> 2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 3fb8c56..c694b12 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -162,8 +162,8 @@ enum AVFrameSideDataType {
> /**
> * 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 timecode format is described in the comments of
> av_timecode_get_smpte_from_framenum()
> + * function in libavutil/timecode.h.
> */
> AV_FRAME_DATA_S12M_TIMECODE,
>
> diff --git a/libavutil/timecode.h b/libavutil/timecode.h
> index ab38e66..b1c1887 100644
> --- a/libavutil/timecode.h
> +++ b/libavutil/timecode.h
> @@ -61,7 +61,21 @@ int av_timecode_adjust_ntsc_framenum2(int framenum, int
> fps);
> * @param tc timecode data correctly initialized
> * @param framenum frame number
> * @return the SMPTE binary representation
> - *> + * the format description as follows, note it's in system byte order: Better avoid contractions in documentation. The result is uint32_t, not char[4]: there is no byte order. > + * 31b: color frame flag (0: unsync mode, 1: sync mode) > + * 30b: drop frame flag (0: non drop, 1: drop) > + * 28b,29b: tens of frames > + * 24-27b: units of frames > + * 23b: PC (NTSC) or BGF0 (PAL) > + * 20b,22b: tens of seconds > + * 16-19b: units of seconds > + * 15b: BGF0 (NTSC) or BGF2 (PAL) > + * 12b,13b: tens of minutes > + * 8-11b: units of minutes > + * 7b: BGF2 (NTSC) or PC (PAL) > + * 6b: BGF1 > + * 4b,5b: tens of hours > + * 0b-3b: units of hours It seems more logical in the opposite order. I do not think this b suffix is very standard. Better be explicit: * bits 24-27: units of frames Also, no reason to make a special case when there are exactly two. And since several numbers are stored the same way, I would suggest to regroup: * bits 8-13: minutes, in BCD * ... * BCD numbers (6 bits): 4 lower bits for units, 2 higher bits for tens. > * @note Frame number adjustment is automatically done in case of drop > timecode, > * you do NOT have to call av_timecode_adjust_ntsc_framenum2(). > * @note The frame number is relative to tc->start. Regards, -- Nicolas George
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
