On date Friday 2016-02-05 11:41:06 +0100, Martin Vignali encoded:
> 2016-01-30 10:44 GMT+01:00 Stefano Sabatini <stefa...@gmail.com>:
>
> > On date Friday 2016-01-29 17:38:13 +0100, Martin Vignali encoded:
> > > 2016-01-29 12:35 GMT+01:00 Stefano Sabatini <stefa...@gmail.com>:
> > [...]
> > > > + AVDictionaryEntry * tcr = av_dict_get(s->metadata, "timecode",
> > > > NULL, 0);
> > > > > + if (tcr){
> > > > > + if (s->nb_streams > 0){
> > > >
> > > > > + rate = s->streams[0]->avg_frame_rate;//Get fps from
> > > > first stream
> > > >
> > > > this looks a bit arbitrary, why the first stream?
> > > >
> > > > > + err = av_timecode_init_from_string(&tc, rate,
> > > > tcr->value, s);
> > > > > + if (err < 0)
> > > > > + return err;
> > > >
> > > > > + tc.start += (int)(seg->time / 1000000.) *
> > > > av_q2d(rate);//second count * fps
> > > >
> > > > You're losing precision here. Consider using the rescaling utilities
> > > > in libavutil/mathematics.h or something like (seg->time * rate.num) /
> > > > (rate.den * 1000000).
> > [...]
> > > Thanks you for your comments, i will make the modifications.
> > >
> > > For the fps issue, you're right, i use the first stream because in my
> > tests
> > > it's always the video stream.
> > > Is there a better way, to get fps ? without choosing one of the stream ?
> >
> > My guess is that timecode is always related to a video stream, right?
> >
> > In this case you can loop through the streams and select the first
> > video stream (check also the select_reference_stream() function in
> > segment.c).
> >
> >
> I follow your proposal, and search the first video stream, to take fps.
>
> In attach the new patch (and a documentation).
>
> Best regards
>
> Martin
>
>
>
> ping
> From c266385a63b5f768e484e0aaccfa27de1f870663 Mon Sep 17 00:00:00 2001
> From: Martin Vignali <martin.vign...@gmail.com>
> Date: Sat, 30 Jan 2016 20:52:54 +0100
> Subject: [PATCH 1/2] add increment timecode option using segment v2
Nit: lavf/segment: add increment timecode option
You could describe a use case in the log (optional).
>
> ---
> libavformat/segment.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/libavformat/segment.c b/libavformat/segment.c
> index 9da5168..933abd1 100644
> --- a/libavformat/segment.c
> +++ b/libavformat/segment.c
> @@ -40,6 +40,7 @@
> #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"
>
> @@ -94,6 +95,7 @@ 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
> @@ -223,6 +225,32 @@ 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;
> + int i;
> +
> + if (seg->increment_tc) {
> + AVDictionaryEntry * tcr = av_dict_get(s->metadata, "timecode", NULL,
> 0);
nit: *tcr
> + 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)
> + return err;
> + tc.start += (seg->time * rate.num) / (rate.den
> * 1000000);/* increment timecode */
This can overflow (yes I know you literally used my own
suggestion). You can use av_mul_q() to avoid that, or cast to floating
point numbers before the multiplication.
> + char buf[AV_TIMECODE_STR_SIZE];
> + av_dict_set(&s->metadata, "timecode",
> + av_timecode_make_string(&tc, buf, 0), 0);/*
> Set the new tc. */
> + break;
> + }
> + }
Please drop the comments in this section, since the code is
self-evident.
> + }
> + else{
> + av_log(s, AV_LOG_ERROR, "can't increment timecode. No timecode
> found");
Style nit:
} else {
Also this should be an AV_LOG_WARNING since it's not an hard failure
(that is, the process will continue to run).
About the message, it could be more descriptive, something like:
"Could not increment timecode, no timecode metadata found"
> + }
> + }
>
> if (write_header) {
> avformat_free_context(oc);
> @@ -946,6 +974,7 @@ static const AVOption options[] = {
> { "segment_start_number", "set the sequence number of the first
> segment", OFFSET(segment_idx), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },
> { "segment_wrap_number", "set the number of wrap before the first
> segment", OFFSET(segment_idx_wrap_nb), AV_OPT_TYPE_INT, {.i64 = 0}, 0,
> INT_MAX, E },
> { "strftime", "set filename expansion with strftime at segment
> creation", OFFSET(use_strftime), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, E },
> + { "increment_tc", "increment timecode between each segment",
> OFFSET(increment_tc), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, 1, E },
> { "break_non_keyframes", "allow breaking segments on non-keyframes",
> OFFSET(break_non_keyframes), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
>
> { "individual_header_trailer", "write header/trailer to each segment",
> OFFSET(individual_header_trailer), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, E },
> --
> 1.9.3 (Apple Git-50)
> From 28844b00c5d80e236abfb719a348fc4be6a202ea Mon Sep 17 00:00:00 2001
> From: Martin Vignali <martin.vign...@gmail.com>
> Date: Sat, 30 Jan 2016 20:54:37 +0100
> Subject: [PATCH 2/2] doc for increment_tc in segment
>
> ---
> doc/muxers.texi | 7 +++++++
> 1 file changed, 7 insertions(+)
Please merge these two patches (use git rebase -i and squeeze the
document patch on top of the first one).
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 4ba8883..0a43dfc 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -997,6 +997,13 @@ implementation for HLS segmentation.
> The segment muxer supports the following options:
>
> @table @option
> +
> +@item increment_tc @var{1|0}
> +Use the @code{increment_tc} function to increment timecode
> +between each segment.
If set to 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
> +@code{0}.
> +
LGTM otherwise.
--
FFmpeg = Fierce & Fundamentalist Moronic Prodigious Enhanced Game
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