[FFmpeg-devel] Fwd: Fwd: libavformat/segment : add option to increment timecode

[Martin Vignali]

2016-02-15 2:35 GMT+01:00 Stefano Sabatini <stefasab at gmail.com>:

> On date Sunday 2016-02-14 15:41:05 +0100, Martin Vignali encoded:
> [...]
> > Hello,
> >
> > New patch attach, i move variable declaration at the top (for
> > AVDictionnaryEntry too).
> > I also remove the return err, in case of an error occured in the
> > av_timecode_init_from_string function.
> > Instead i put an AV Log Warning, and the timecode is not modified.
> >
> > Best regards
> >
> > Martin
>
> > From 5e162acdc9ec4602c3263796c07ca4226b314e14 Mon Sep 17 00:00:00 2001
> > From: Martin Vignali <martin.vignali at gmail.com>
> > Date: Sun, 14 Feb 2016 15:32:27 +0100
> > Subject: [PATCH] lavf/segment: add increment timecode option
> >
> > for example you can split a file, keeping a continuous timecode between
> > each segment :
> >
> > ffmpeg -i src.mov -timecode 10:00:00:00 -vcodec copy -f segment \
> > -segment_time 2 -reset_timestamps 1 -increment_tc 1 target_%03d.mov
> > ---
> >  doc/muxers.texi       |  7 +++++++
> >  libavformat/segment.c | 31 +++++++++++++++++++++++++++++++
> >  2 files changed, 38 insertions(+)
> >
> > diff --git a/doc/muxers.texi b/doc/muxers.texi
> > index 2e6bb4c..21f3525 100644
> > --- a/doc/muxers.texi
> > +++ b/doc/muxers.texi
> > @@ -1017,6 +1017,13 @@ implementation for HLS segmentation.
> >  The segment muxer supports the following options:
> >
> >  @table @option
> > +
> > + at item increment_tc @var{1|0}
> > +if set to @code{1}, increment timecode between each segment
> > +If this is selected, the input need to have
> > +a timecode in the first video stream. Default value is
> > + at code{0}.
> > +
> >  @item reference_stream @var{specifier}
> >  Set the reference stream, as specified by the string @var{specifier}.
> >  If @var{specifier} is set to @code{auto}, the reference is chosen
> > diff --git a/libavformat/segment.c b/libavformat/segment.c
> > index dd3b092..00680b3 100644
> > --- a/libavformat/segment.c
> > +++ b/libavformat/segment.c
> > @@ -41,6 +41,7 @@
> >  #include "libavutil/parseutils.h"
> >  #include "libavutil/mathematics.h"
> >  #include "libavutil/time.h"
> > +#include "libavutil/timecode.h"
> >  #include "libavutil/time_internal.h"
> >  #include "libavutil/timestamp.h"
> >
> > @@ -95,6 +96,7 @@ typedef struct SegmentContext {
> >      char *time_str;        ///< segment duration specification string
> >      int64_t time;          ///< segment duration
> >      int use_strftime;      ///< flag to expand filename with strftime
> > +    int increment_tc;      ///< flag to increment timecode if found
> >
> >      char *times_str;       ///< segment times specification string
> >      int64_t *times;        ///< list of segment interval specification
> > @@ -227,6 +229,34 @@ static int segment_start(AVFormatContext *s, int
> write_header)
> >      SegmentContext *seg = s->priv_data;
> >      AVFormatContext *oc = seg->avf;
> >      int err = 0;
> > +    AVTimecode tc;
> > +    AVRational rate;
> > +    AVDictionaryEntry *tcr;
> > +    char buf[AV_TIMECODE_STR_SIZE];
> > +    int i;
> > +
> > +    if (seg->increment_tc) {
> > +        tcr = av_dict_get(s->metadata, "timecode", NULL, 0);
> > +        if (tcr) {
> > +            /* search the first video stream */
> > +            for (i = 0; i < s->nb_streams; i++) {
> > +                if (s->streams[i]->codec->codec_type ==
> AVMEDIA_TYPE_VIDEO) {
> > +                    rate = s->streams[i]->avg_frame_rate;/* Get fps
> from the video stream */
>
>
> > +                    err = av_timecode_init_from_string(&tc, rate,
> tcr->value, s);
> > +                    if (err < 0) {
> > +                        av_log(s, AV_LOG_WARNING, "Could not increment
> timecode, error occured during timecode creation.");
> > +                        break;
> > +                    }
>
> > +                    tc.start += (int)
> av_q2d(av_mul_q(av_make_q(seg->time, 1000000 ), rate));/* increment
> timecode */
>
> nit: 1000000_) => 1000000)
>
> Also, reading from the timecode.c code it looks like the increment
> must be expressed in fps units.
>

Sorry don't understand what's wrong now. In my tests, the timecode
incrementation is correct (but maybe i missed a special case)


>
> Finally, you are using the segment->time, which is different from the
> effective segment duration. Could you set the metadata in segment_end,
> where the exact duration is known?
>

Do you know how can i get the exact segment duration ?


Martin