[FFmpeg-devel] [PATCH 2/3] avutil/timecode: fix av_timecode_get_smpte_from_framenum with 50/60 fps
lance.lmwang at gmail.com
lance.lmwang at gmail.com
Wed Jul 22 02:12:21 EEST 2020
On Mon, Jul 20, 2020 at 11:04:38PM +0200, Marton Balint wrote:
> 50/60 fps timecode is using the field bit (which is the same as the phase
> correction bit) to signal the least significant bit of a 50/60 fps timecode.
> See SMPTE ST 12-1:2014 section 12.1.
>
> Let's add support for this by using the recently added av_timecode_get_smpte
> function which handles this properly.
>
> This change affects DV and MXF encoder, MXF has no fate for 50/60fps content,
> DV does, therefore the changes. It also affects decklink indev.
>
> MediaInfo (a recent version) confirms that half-frame timecode must be
> inserted. (although MediaInfo does not seem to check the field flag).
> MXFInspect confirms valid timecode insertion to the System Item of MXF files.
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> libavutil/timecode.c | 15 +--------------
> libavutil/timecode.h | 7 +++----
> tests/ref/vsynth/vsynth1-dv-hd | 2 +-
> tests/ref/vsynth/vsynth2-dv-hd | 2 +-
> tests/ref/vsynth/vsynth3-dv-hd | 2 +-
> tests/ref/vsynth/vsynth_lena-dv-hd | 2 +-
> 6 files changed, 8 insertions(+), 22 deletions(-)
>
> diff --git a/libavutil/timecode.c b/libavutil/timecode.c
> index cca53d73c4..cb916970ef 100644
> --- a/libavutil/timecode.c
> +++ b/libavutil/timecode.c
> @@ -65,20 +65,7 @@ uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum)
> ss = framenum / fps % 60;
> mm = framenum / (fps*60) % 60;
> hh = framenum / (fps*3600) % 24;
> - return 0 << 31 | // color frame flag (0: unsync mode, 1: sync mode)
> - drop << 30 | // drop frame flag (0: non drop, 1: drop)
> - (ff / 10) << 28 | // tens of frames
> - (ff % 10) << 24 | // units of frames
> - 0 << 23 | // PC (NTSC) or BGF0 (PAL)
> - (ss / 10) << 20 | // tens of seconds
> - (ss % 10) << 16 | // units of seconds
> - 0 << 15 | // BGF0 (NTSC) or BGF2 (PAL)
> - (mm / 10) << 12 | // tens of minutes
> - (mm % 10) << 8 | // units of minutes
> - 0 << 7 | // BGF2 (NTSC) or PC (PAL)
> - 0 << 6 | // BGF1
> - (hh / 10) << 4 | // tens of hours
> - (hh % 10); // units of hours
> + return av_timecode_get_smpte(tc->rate, drop, hh, mm, ss, ff);
> }
>
> uint32_t av_timecode_get_smpte(AVRational rate, int drop, int hh, int mm, int ss, int ff)
> diff --git a/libavutil/timecode.h b/libavutil/timecode.h
> index 5801330921..e54b116e93 100644
> --- a/libavutil/timecode.h
> +++ b/libavutil/timecode.h
> @@ -66,11 +66,11 @@ int av_timecode_adjust_ntsc_framenum2(int framenum, int fps);
> * the format description as follows:
> * bits 0-5: hours, in BCD(6bits)
> * bits 6: BGF1
> - * bits 7: BGF2 (NTSC) or PC (PAL)
> + * bits 7: BGF2 (NTSC) or FIELD (PAL)
If the format is coming from SMPTE 314m-1999, 4.4.2.2.1 Time code pack (TC), then
it use PC instead of FIELD for the interpretation of the bits.
PC: Biphase mark polarity correction
0 = even
1 = odd
About the bits interpretation:
FIELD is used by VITC
https://en.wikipedia.org/wiki/Vertical_interval_timecode
PC is used by LTC
https://en.wikipedia.org/wiki/Linear_timecode
So I prefer to change to PC/FIELD instead of FIELD only if want to update the
interpretation of the bits.
> * bits 8-14: minutes, in BCD(7bits)
> * bits 15: BGF0 (NTSC) or BGF2 (PAL)
> * bits 16-22: seconds, in BCD(7bits)
> - * bits 23: PC (NTSC) or BGF0 (PAL)
> + * bits 23: FIELD (NTSC) or BGF0 (PAL)
> * bits 24-29: frames, in BCD(6bits)
> * bits 30: drop frame flag (0: non drop, 1: drop)
> * bits 31: color frame flag (0: unsync mode, 1: sync mode)
> @@ -78,8 +78,7 @@ int av_timecode_adjust_ntsc_framenum2(int framenum, int fps);
> * @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.
> - * @note Color frame (CF), binary group flags (BGF) and biphase mark polarity
> - * correction (PC) bits are set to zero.
> + * @note Color frame (CF) and binary group flags (BGF) bits are set to zero.
> */
> uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum);
>
> diff --git a/tests/ref/vsynth/vsynth1-dv-hd b/tests/ref/vsynth/vsynth1-dv-hd
> index e22f28c704..a93ce50ec0 100644
> --- a/tests/ref/vsynth/vsynth1-dv-hd
> +++ b/tests/ref/vsynth/vsynth1-dv-hd
> @@ -1,4 +1,4 @@
> -77f146c73a24495495c649f1e0d26fee *tests/data/fate/vsynth1-dv-hd.dv
> +ce9f887af2391edbfcb21675962db54c *tests/data/fate/vsynth1-dv-hd.dv
> 14400000 tests/data/fate/vsynth1-dv-hd.dv
> 34b78cf725346c7f819c9d6209b8299a *tests/data/fate/vsynth1-dv-hd.out.rawvideo
> stddev: 4.30 PSNR: 35.45 MAXDIFF: 74 bytes: 7603200/ 7603200
> diff --git a/tests/ref/vsynth/vsynth2-dv-hd b/tests/ref/vsynth/vsynth2-dv-hd
> index 5c4ed86fe7..9552c31948 100644
> --- a/tests/ref/vsynth/vsynth2-dv-hd
> +++ b/tests/ref/vsynth/vsynth2-dv-hd
> @@ -1,4 +1,4 @@
> -168f80951daf5eeefacac33fd06db87d *tests/data/fate/vsynth2-dv-hd.dv
> +c152c7c3f9ef8f404b4bb7a388b947be *tests/data/fate/vsynth2-dv-hd.dv
> 14400000 tests/data/fate/vsynth2-dv-hd.dv
> 15dbe911532aca81c67bdd2846419027 *tests/data/fate/vsynth2-dv-hd.out.rawvideo
> stddev: 1.75 PSNR: 43.26 MAXDIFF: 34 bytes: 7603200/ 7603200
> diff --git a/tests/ref/vsynth/vsynth3-dv-hd b/tests/ref/vsynth/vsynth3-dv-hd
> index ed94d08155..d0420d6f07 100644
> --- a/tests/ref/vsynth/vsynth3-dv-hd
> +++ b/tests/ref/vsynth/vsynth3-dv-hd
> @@ -1,4 +1,4 @@
> -1211b843d8dde81c583023e15beff35a *tests/data/fate/vsynth3-dv-hd.dv
> +973b0856d1d94793bd6e8951284e642d *tests/data/fate/vsynth3-dv-hd.dv
> 14400000 tests/data/fate/vsynth3-dv-hd.dv
> a038ad7c3c09f776304ef7accdea9c74 *tests/data/fate/vsynth3-dv-hd.out.rawvideo
> stddev: 0.00 PSNR:999.99 MAXDIFF: 0 bytes: 86700/ 86700
> diff --git a/tests/ref/vsynth/vsynth_lena-dv-hd b/tests/ref/vsynth/vsynth_lena-dv-hd
> index 6764f03c35..8b87da40ba 100644
> --- a/tests/ref/vsynth/vsynth_lena-dv-hd
> +++ b/tests/ref/vsynth/vsynth_lena-dv-hd
> @@ -1,4 +1,4 @@
> -fa8df53531f9e58f90bc9a33e5c78ca8 *tests/data/fate/vsynth_lena-dv-hd.dv
> +30652b3740a32fa8bcee3b06a66b1dd2 *tests/data/fate/vsynth_lena-dv-hd.dv
> 14400000 tests/data/fate/vsynth_lena-dv-hd.dv
> 4db4175c80ea1f16b7ec303611b8873a *tests/data/fate/vsynth_lena-dv-hd.out.rawvideo
> stddev: 1.49 PSNR: 44.66 MAXDIFF: 27 bytes: 7603200/ 7603200
> --
> 2.26.2
>
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--
Thanks,
Limin Wang
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