[FFmpeg-devel] [PATCH 1/8] avutil/timecode: fix av_timecode_get_smpte_from_framenum with 50/60 fps
Marton Balint
cus at passwd.hu
Sun Sep 13 00:07:24 EEST 2020
On Sat, 5 Sep 2020, Marton Balint wrote:
> SMPTE 12M timecode can only count frames up to 39, because the tens-of-frames
> value is stored in 2 bit. In order to resolve this 50/60 fps SMPTE timecode is
> using the field bit (which is the same bit 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.
>
> Therefore we slightly change the format of the return value of
> av_timecode_get_smpte_from_framenum and AV_FRAME_DATA_S12M_TIMECODE and start
> using the previously unused Phase Correction bit as Field bit. (As the SMPTE
> standard suggests)
>
> We add 50/60 fps support to av_timecode_get_smpte_from_framenum by calling the
> recently added av_timecode_get_smpte function in it which already handles this
> properly.
>
> This change affects the decklink indev and the DV and MXF muxers. MXF has no
> fate test for 50/60fps content, DV does, therefore the changes.
>
> MediaInfo (a recent version) confirms that half-frame timecode must be inserted
> to DV. MXFInspect confirms valid timecode insertion to the System Item of MXF
> files. For MXF, also see EBU R122.
>
> Note that for DV the field flag is not used because in the HDV specs (SMPTE
> 370M) it is still defined as biphase mark polarity correction flag. So it
> should not matter that the DV muxer overrides the field bit.
Will apply the series soon.
Thanks,
Marton
>
> 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)
> * 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 6b6d6e8159..3f2f9cc843 100644
> --- a/tests/ref/vsynth/vsynth1-dv-hd
> +++ b/tests/ref/vsynth/vsynth1-dv-hd
> @@ -1,4 +1,4 @@
> -22d1d62a834fe8416fe79c51760012c1 *tests/data/fate/vsynth1-dv-hd.dv
> +b2bcafc74dec5f9ca516cb25dd07459b *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 c6dcb5a953..0a5046e4ec 100644
> --- a/tests/ref/vsynth/vsynth2-dv-hd
> +++ b/tests/ref/vsynth/vsynth2-dv-hd
> @@ -1,4 +1,4 @@
> -4270e5d552e0a05193f44bff75c2d271 *tests/data/fate/vsynth2-dv-hd.dv
> +a9a4c750f7720e83d538d36c318be787 *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 d069e6980e..11a51b18b8 100644
> --- a/tests/ref/vsynth/vsynth3-dv-hd
> +++ b/tests/ref/vsynth/vsynth3-dv-hd
> @@ -1,4 +1,4 @@
> -2f81f3ccec178ba2fd9d3e3b46f33670 *tests/data/fate/vsynth3-dv-hd.dv
> +63512193a0da09e15815c1be1b9c4fa5 *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 aba756c5f1..8711b6fa2f 100644
> --- a/tests/ref/vsynth/vsynth_lena-dv-hd
> +++ b/tests/ref/vsynth/vsynth_lena-dv-hd
> @@ -1,4 +1,4 @@
> -01a61c53943a421fa6a5e03dbc205972 *tests/data/fate/vsynth_lena-dv-hd.dv
> +f17abb38ed2f416d57f3b956fae5dc82 *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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