On Tue, Sep 09, 2025 at 02:40:50PM +0200, Jerome Martinez via ffmpeg-devel
wrote:
> timecode.c | 104
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> timecode.h | 22 ++++++++++++
> 2 files changed, 126 insertions(+)
> 8969dd4cc3cc1d77acde18a6eae065e9413757b2
> 0004-32-bit-timecode-to-64-bit-RFC-5484-timecode-function.patch
> >From 36cc44569a898c8401944bc16b791632fd4ac985 Mon Sep 17 00:00:00 2001
> From: Dave Rice <dave at dericed.com>
> Date: Mon, 30 Jun 2025 00:00:00 +0200
> Subject: [PATCH 4/7] 32-bit timecode to 64-bit RFC 5484 timecode functions
>
> ---
> libavutil/timecode.c | 104 +++++++++++++++++++++++++++++++++++++++++++
> libavutil/timecode.h | 22 +++++++++
> 2 files changed, 126 insertions(+)
>
> diff --git a/libavutil/timecode.c b/libavutil/timecode.c
> index bca16b6ac2..81fb66a5e4 100644
> --- a/libavutil/timecode.c
> +++ b/libavutil/timecode.c
> @@ -243,3 +243,107 @@ int av_timecode_init_from_string(AVTimecode *tc,
> AVRational rate, const char *st
>
> return av_timecode_init_from_components(tc, rate, flags, hh, mm, ss, ff,
> log_ctx);
> }
> +
> +static int bcd_to_int(int bcd) {
> + return ((bcd >> 4) & 0xF) * 10 + (bcd & 0xF);
> +}
> +
> +uint64_t av_timecode_expand_to_64bit(uint32_t tc32)
> +{
> + uint64_t tc64 = 0;
> +
> + int hours_bcd = tc32 & 0x3F; // bits 0-5
> + int bgf1 = (tc32 >> 6) & 0x1; // bit 6
> + int bgf2 = (tc32 >> 7) & 0x1; // bit 7
> + int minutes_bcd = (tc32 >> 8) & 0x7F; // bits 8-14
> + int bgf0 = (tc32 >> 15) & 0x1; // bit 15
> + int seconds_bcd = (tc32 >> 16) & 0x7F; // bits 16-22
> + int frames_bcd = (tc32 >> 24) & 0x3F; // bits 24-29
> + int drop = (tc32 >> 30) & 0x1; // bit 30
> + int color = (tc32 >> 31) & 0x1; // bit 31
> +
> + int hours = bcd_to_int(hours_bcd);
> + int minutes = bcd_to_int(minutes_bcd);
> + int seconds = bcd_to_int(seconds_bcd);
> + int frames = bcd_to_int(frames_bcd);
> +
> + // Units and tens
> + int uh = hours % 10, th = hours / 10;
> + int um = minutes % 10, tm = minutes / 10;
> + int us = seconds % 10, ts = seconds / 10;
> + int uf = frames % 10, tf = frames / 10;
> +
> + // Assign bits as per RFC 5484 layout
> + tc64 |= (uint64_t)(uf & 0xF) << 0; // Units of frames
uf is limited to 0..9 it doesnt need &0xf
> + tc64 |= 0 << 4; // First binary group
> + tc64 |= (uint64_t)(tf & 0x3) << 8; // Tens of frames (2 bits)
> + tc64 |= (uint64_t)drop << 10; // Drop frame flag
> + tc64 |= (uint64_t)color << 11; // Color frame flag
> + tc64 |= 0 << 12; // Second binary group
> +
> + tc64 |= (uint64_t)(us & 0xF) << 16; // Units of seconds
us is limited to 0..9 it doesnt need &0xf
> + tc64 |= 0 << 20; // Third binary group
> + tc64 |= (uint64_t)(ts & 0x7) << 24; // Tens of seconds
> + tc64 |= 0 << 27; // Polarity correction
> + tc64 |= 0 << 28; // Fourth binary group
> +
> + tc64 |= (uint64_t)(um & 0xF) << 32; // Units of minutes
same
> + tc64 |= (uint64_t)0 << 36; // Fifth binary group
> + tc64 |= (uint64_t)(tm & 0x7) << 40; // Tens of minutes
> + tc64 |= (uint64_t)bgf0 << 43; // BGF0
> + tc64 |= (uint64_t)0 << 44; // Sixth binary group
> +
> + tc64 |= (uint64_t)(uh & 0xF) << 48; // Units of hours
same
> + tc64 |= (uint64_t)0 << 52; // Seventh binary group
> + tc64 |= (uint64_t)(th & 0x3) << 56; // Tens of hours
> + tc64 |= (uint64_t)bgf1 << 58; // BGF1
> + tc64 |= (uint64_t)bgf2 << 59; // BGF2
> + tc64 |= (uint64_t)0 << 60; // Eighth binary group
> +
> + return tc64;
> +}
> +
> +static int int_to_bcd(int val) {
> + return ((val / 10) << 4) | (val % 10);
> +}
> +
> +uint32_t av_timecode_parse_from_64bit(uint64_t tc64)
> +{
> + uint32_t tc32 = 0;
> +
> + int uf = (tc64 >> 0) & 0xF; // Ones of frames
> + int tf = (tc64 >> 8) & 0x3; // Tens of frames
> + int drop = (tc64 >> 10) & 0x1;
> + int color= (tc64 >> 11) & 0x1;
> +
> + int us = (tc64 >> 16) & 0xF; // Ones of seconds
> + int ts = (tc64 >> 24) & 0x7; // Tens of seconds
> +
> + int um = (tc64 >> 32) & 0xF; // Ones of minutes
> + int tm = (tc64 >> 40) & 0x7; // Tens of minutes
> + int bgf0 = (tc64 >> 43) & 0x1;
> +
> + int uh = (tc64 >> 48) & 0xF; // Ones of hours
> + int th = (tc64 >> 56) & 0x3; // Tens of hours
> + int bgf1 = (tc64 >> 58) & 0x1;
> + int bgf2 = (tc64 >> 59) & 0x1;
> +
> + int hours = int_to_bcd(th * 10 + uh);
> + int minutes = int_to_bcd(tm * 10 + um);
> + int seconds = int_to_bcd(ts * 10 + us);
> + int frames = int_to_bcd(tf * 10 + uf);
> +
> + // Assemble tc32 using the FFmpeg SMPTE 32-bit format
> + tc32 |= (hours & 0x3F) << 0; // bits 0-5: hours (BCD)
> + tc32 |= (bgf1 & 0x1) << 6; // bit 6: BGF1
> + tc32 |= (bgf2 & 0x1) << 7; // bit 7: BGF2 (or FIELD)
> + tc32 |= (minutes & 0x7F) << 8; // bits 8-14: minutes (BCD)
> + tc32 |= (bgf0 & 0x1) << 15; // bit 15: BGF0
> + tc32 |= (seconds & 0x7F) << 16; // bits 16-22: seconds (BCD)
> + tc32 |= 0 << 23; // bit 23: FIELD (set to 0)
> + tc32 |= (frames & 0x3F) << 24; // bits 24-29: frames (BCD)
> + tc32 |= (drop & 0x1) << 30; // bit 30: drop frame flag
> + tc32 |= (color & 0x1) << 31; // bit 31: color frame flag
> +
> + return tc32;
> +}
should some of these functions have checks on the input being valid ?
or is such a check harmfull ? or already done elsewhere ?
thx
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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