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

[Stefano Sabatini]

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.

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?

[...]
-- 
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