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timecode: move dropframe code and doxycomment it.

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This is based on the original work by Baptiste Coudurier.
This commit is contained in:
Clément Bœsch 2011-07-06 14:55:06 +02:00 committed by Clément Bœsch
parent 5231454560
commit 51fb933dd0
3 changed files with 19 additions and 7 deletions
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9
libavcodec/mpeg12enc.c
View File

@ -299,13 +299,8 @@ static void mpeg1_encode_sequence_header(MpegEncContext *s)
time_code = s->current_picture_ptr->f.coded_picture_number + s->avctx->timecode_frame_start;
s->gop_picture_number = s->current_picture_ptr->f.coded_picture_number;
if (s->tc.drop) {
/* only works for NTSC 29.97 */
int d = time_code / 17982;
int m = time_code % 17982;
//if (m < 2) m += 2; /* not needed since -2,-1 / 1798 in C returns 0 */
time_code += 18 * d + 2 * ((m - 2) / 1798);
}
if (s->tc.drop)
time_code = ff_framenum_to_drop_timecode(time_code);
put_bits(&s->pb, 5, (uint32_t)((time_code / (fps * 3600)) % 24));
put_bits(&s->pb, 6, (uint32_t)((time_code / (fps * 60)) % 60));
put_bits(&s->pb, 1, 1);

9
libavcodec/timecode.c
View File

@ -28,6 +28,15 @@
#include "timecode.h"
#include "libavutil/log.h"
int ff_framenum_to_drop_timecode(int frame_num)
{
/* only works for NTSC 29.97 */
int d = frame_num / 17982;
int m = frame_num % 17982;
//if (m < 2) m += 2; /* not needed since -2,-1 / 1798 in C returns 0 */
return frame_num + 18 * d + 2 * ((m - 2) / 1798);
}
int ff_init_smtpe_timecode(void *avcl, struct ff_timecode *tc)
{
int hh, mm, ss, ff, fps;

8
libavcodec/timecode.h
View File

@ -43,6 +43,14 @@ struct ff_timecode {
AVRational rate; ///< Frame rate in rationnal form
};
/**
* @brief Adjust frame number for NTSC drop frame time code
* @param frame_num Actual frame number to adjust
* @return Adjusted frame number
* @warning Adjustment is only valid in NTSC 29.97
*/
int ff_framenum_to_drop_timecode(int frame_num);
/**
* Parse SMTPE 12M time representation (hh:mm:ss[:;.]ff). str and rate fields
* from tc struct must be set.