[FFmpeg-devel] [PATCH 02/12] lavu: add public timecode API.
Stefano Sabatini
stefasab at gmail.com
Tue Jan 24 13:47:30 CET 2012
On date Monday 2012-01-23 17:04:21 +0100, Clément Bœsch encoded:
> From: Clément Bœsch <clement.boesch at smartjog.com>
>
> ---
> doc/APIchanges | 3 +
> libavutil/Makefile | 2 +
> libavutil/avutil.h | 4 +-
> libavutil/timecode.c | 174 ++++++++++++++++++++++++++++++++++++++++++++++++++
> libavutil/timecode.h | 125 ++++++++++++++++++++++++++++++++++++
> 5 files changed, 306 insertions(+), 2 deletions(-)
> create mode 100644 libavutil/timecode.c
> create mode 100644 libavutil/timecode.h
[...]
> +/**
> + * @file
> + * Timecode helpers header
> + */
> +
> +#ifndef AVUTIL_TIMECODE_H
> +#define AVUTIL_TIMECODE_H
> +
> +#include <stdint.h>
> +#include "rational.h"
> +
> +#define AV_TIMECODE_STR_SIZE 16
> +
> +#define AV_TIMECODE_OPTION(ctx, string_field, flags) \
> + "timecode", "set timecode value following hh:mm:ss[:;.]ff format, " \
> + "use ';' or '.' before frame number for drop frame", \
> + offsetof(ctx, string_field), \
> + AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, flags
> +
> +enum AVTimecodeFlag {
> + AV_TIMECODE_FLAG_DROPFRAME = 1<<0, ///< timecode is drop frame
> + AV_TIMECODE_FLAG_24HOURSMAX = 1<<1, ///< timecode wraps after 24 hours
> + AV_TIMECODE_FLAG_ALLOWNEGATIVE = 1<<2, ///< negative time values are allowed
> +};
> +
> +typedef struct {
> + int start; ///< timecode frame start (first base frame number)
> + uint32_t flags; ///< flags such as drop frame, +24 hours support, ...
> + AVRational rate; ///< frame rate in rational form
> + unsigned fps; ///< frame per second; must be consistent with the rate field
> +} AVTimecode;
> +
> +/**
> + * Adjust frame number for NTSC drop frame time code.
> + *
> + * @param framenum frame number to adjust
> + * @return adjusted frame number
> + * @warning adjustment is only valid in NTSC 29.97
> + */
> +int av_timecode_adjust_ntsc_framenum(int framenum);
> +
> +/**
> + * Convert frame number to SMPTE 12M binary representation.
> + *
> + * @param tc timecode data correctly initialized
> + * @param framenum frame number
> + * @return the SMPTE binary representation
> + *
> + * @note Frame number adjustment is automatically done in case of drop timecode,
> + * you do NOT have to call av_adjust_ntsc_framenum().
nit++: no complete sentence, lowcased and no dot at the end
> + * @note The frame number is relative to tc->start.
same here
> + */
> +uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum);
Nit: get->make is maybe more approriate (as noted by Alexander
Strasser in a recent mail)
> +
> +/**
> + * Load timecode string in buf.
> + *
> + * @param buf destination buffer, must be at least AV_TIMECODE_STR_SIZE long
> + * @param tc timecode data correctly initialized
> + * @param framenum frame number
> + * @return the buf parameter
> + *
> + * @note Timecode representation can be a negative timecode and have more than
> + * 24 hours, but will only be honored if the flags are correctly set.
> + * @note The frame number is relative to tc->start.
ditto
> + */
> +char *av_timecode_get_string(char *buf, const AVTimecode *tc, int framenum);
ditto: get -> make?
> +/**
> + * Get the timecode string from the 25-bit timecode format (MPEG GOP format).
> + *
> + * @param buf destination buffer, must be at least AV_TIMECODE_STR_SIZE long
> + * @param tc25bit the 25-bits timecode
> + * @return the buf parameter
> + */
> +char *av_timecode_get_mpegtc_string(char *buf, uint32_t tc25bit);
make?
> +
> +/**
> + * Init a timecode struct with the passed parameters.
> + *
> + * @param log_ctx a pointer to an arbitrary struct of which the first field
> + * is a pointer to an AVClass struct (used for av_log)
> + * @param tc pointer to an allocated AVTimecode
> + * @param rate frame rate in rational form
> + * @param flags miscellaneous flags such as drop frame, +24 hours, ...
> + * (see AVTimecodeFlag)
> + * @param frame_start the first frame number
> + * @return 0 on success, AVERROR otherwise
> + */
> +int av_timecode_init(void *log_ctx, AVTimecode *tc, AVRational rate, int flags, int frame_start);
> +
> +/**
> + * Parse timecode representation (hh:mm:ss[:;.]ff).
> + *
> + * @param log_ctx a pointer to an arbitrary struct of which the first field is a
> + * pointer to an AVClass struct (used for av_log).
> + * @param tc pointer to an allocated AVTimecode
> + * @param rate frame rate in rational form
> + * @param str timecode string which will determine the frame start
> + * @return 0 on success, AVERROR otherwise
> + */
> +int av_timecode_init_from_string(void *log_ctx, AVTimecode *tc, AVRational rate, const char *str);
For these two, either make or init should be fine, I have no strong
opinion though but a slight bias towards "make" for internal
consistency reasons.
--
FFmpeg = Frightening and Funny Majestic Puristic Experimenting Generator
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