[FFmpeg-devel] [PATCH 2/7] lavf/segment: add option to segment by chapter

Rodger Combs rodger.combs at gmail.com
Tue Aug 1 10:18:17 EEST 2017


This was pretty confusing whether it uses strlcpy or strncpy, so I'm switching it to AVBPrintf.

> On Aug 1, 2017, at 01:54, Steven Liu <lingjiujianke at gmail.com> wrote:
> 
> 2017-08-01 14:33 GMT+08:00 Rodger Combs <rodger.combs at gmail.com <mailto:rodger.combs at gmail.com>>:
>> ---
>> doc/muxers.texi       |  6 +++++
>> libavformat/segment.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++----
>> libavformat/version.h |  2 +-
>> 3 files changed, 67 insertions(+), 6 deletions(-)
>> 
>> diff --git a/doc/muxers.texi b/doc/muxers.texi
>> index 94472ce..23ef2e7 100644
>> --- a/doc/muxers.texi
>> +++ b/doc/muxers.texi
>> @@ -1538,6 +1538,12 @@ This option specifies to start a new segment whenever a reference
>> stream key frame is found and the sequential number (starting from 0)
>> of the frame is greater or equal to the next value in the list.
>> 
>> + at item segment_chapters @var{1|0}
>> +Split each chapter into its own segment. Metadata from the chapters
>> +will be written to the corresponding segments. If this option is selected
>> +and the filename contains tokens in the format @code{$varname$}, they
>> +will be replaced by the corresponding metadata values.
>> +
>> @item segment_wrap @var{limit}
>> Wrap around segment index once it reaches @var{limit}.
>> 
>> diff --git a/libavformat/segment.c b/libavformat/segment.c
>> index 0e8bcdd..590f62b 100644
>> --- a/libavformat/segment.c
>> +++ b/libavformat/segment.c
>> @@ -106,6 +106,8 @@ typedef struct SegmentContext {
>>     int frame_count;       ///< total number of reference frames
>>     int segment_frame_count; ///< number of reference frames in the segment
>> 
>> +    int split_chapters;    ///< split on chapter markers
>> +
>>     int64_t time_delta;
>>     int  individual_header_trailer; /**< Set by a private option. */
>>     int  write_header_trailer; /**< Set by a private option. */
>> @@ -186,6 +188,43 @@ static int segment_mux_init(AVFormatContext *s)
>>     return 0;
>> }
>> 
>> +static int replace_variables(AVFormatContext *oc)
>> +{
>> +    char name[sizeof(oc->filename)];
>> +    char *p = name;
>> +    char *out = oc->filename;
>> +    strncpy(name, oc->filename, sizeof(name));
>> +    while (*p) {
>> +        char c = *p++;
>> +        if (c == '$') {
>> +            if (*p == '$') {
>> +                p++;
>> +                goto append;
>> +            } else {
>> +                int len;
>> +                const char *val;
>> +                const AVDictionaryEntry *e;
>> +                int end = strcspn(p, "$");
>> +                if (p[end] == '\0')
>> +                    continue;
>> +                p[end] = '\0';
>> +                e = av_dict_get(oc->metadata, p, NULL, 0);
>> +                val = e ? e->value : "(unknown)";
>> +                len = strlen(val);
>> +                strncpy(out, val, oc->filename + sizeof(oc->filename) - 1 - out);
> why not av_strlcpy?
>> +                out = FFMIN(oc->filename + sizeof(oc->filename) - 1, out + len);
>> +                p += end + 1;
>> +            }
>> +        } else {
>> +append:
>> +            if (out - oc->filename < sizeof(oc->filename) - 1)
>> +                *out++ = c;
>> +        }
>> +    }
>> +    *out = '\0';
>> +    return 0;
>> +}
>> +
>> static int set_segment_filename(AVFormatContext *s)
>> {
>>     SegmentContext *seg = s->priv_data;
>> @@ -210,6 +249,9 @@ static int set_segment_filename(AVFormatContext *s)
>>         return AVERROR(EINVAL);
>>     }
>> 
>> +    if (seg->split_chapters)
>> +        replace_variables(oc);
>> +
>>     /* copy modified name in list entry */
>>     size = strlen(av_basename(oc->filename)) + 1;
>>     if (seg->entry_prefix)
>> @@ -236,6 +278,8 @@ static int segment_start(AVFormatContext *s, int write_header)
>>         if ((err = segment_mux_init(s)) < 0)
>>             return err;
>>         oc = seg->avf;
>> +        if (seg->split_chapters && seg->segment_count < s->nb_chapters && (err = av_dict_copy(&oc->metadata, s->chapters[seg->segment_count]->metadata, 0)) < 0)
>> +            return err;
>>     }
>> 
>>     seg->segment_idx++;
>> @@ -659,10 +703,14 @@ static int seg_init(AVFormatContext *s)
>>                "you can use output_ts_offset instead of it\n");
>>     }
>> 
>> -    if (!!seg->time_str + !!seg->times_str + !!seg->frames_str > 1) {
>> +    if (seg->segment_idx < 0)
>> +        seg->segment_idx = seg->split_chapters;
>> +
>> +    if (!!seg->time_str + !!seg->times_str + !!seg->frames_str + !!seg->split_chapters > 1) {
>>         av_log(s, AV_LOG_ERROR,
>> -               "segment_time, segment_times, and segment_frames options "
>> -               "are mutually exclusive, select just one of them\n");
>> +               "segment_time, segment_times, segment_frames, and "
>> +               "segment_chapters options are mutually exclusive; "
>> +               "select just one of them\n");
>>         return AVERROR(EINVAL);
>>     }
>> 
>> @@ -672,7 +720,7 @@ static int seg_init(AVFormatContext *s)
>>     } else if (seg->frames_str) {
>>         if ((ret = parse_frames(s, &seg->frames, &seg->nb_frames, seg->frames_str)) < 0)
>>             return ret;
>> -    } else {
>> +    } else if (!seg->split_chapters) {
>>         /* set default value if not specified */
>>         if (!seg->time_str)
>>             seg->time_str = av_strdup("2");
>> @@ -739,6 +787,9 @@ static int seg_init(AVFormatContext *s)
>>     if ((ret = segment_mux_init(s)) < 0)
>>         return ret;
>> 
>> +    if (seg->split_chapters && s->nb_chapters && (ret = av_dict_copy(&seg->avf->metadata, s->chapters[0]->metadata, 0)) < 0)
>> +        return ret;
>> +
>>     if ((ret = set_segment_filename(s)) < 0)
>>         return ret;
>>     oc = seg->avf;
>> @@ -860,6 +911,9 @@ calc_times:
>>     } else if (seg->frames) {
>>         start_frame = seg->segment_count < seg->nb_frames ?
>>             seg->frames[seg->segment_count] : INT_MAX;
>> +    } else if (seg->split_chapters) {
>> +        end_pts = seg->segment_count + 1 < s->nb_chapters ?
>> +            av_rescale_q(s->chapters[seg->segment_count]->end, s->chapters[seg->segment_count]->time_base, AV_TIME_BASE_Q) : INT64_MAX;
>>     } else {
>>         if (seg->use_clocktime) {
>>             int64_t avgt = av_gettime();
>> @@ -1042,9 +1096,10 @@ static const AVOption options[] = {
>>     { "segment_time_delta","set approximation value used for the segment times", OFFSET(time_delta), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, 0, E },
>>     { "segment_times",     "set segment split time points",              OFFSET(times_str),AV_OPT_TYPE_STRING,{.str = NULL},  0, 0,       E },
>>     { "segment_frames",    "set segment split frame numbers",            OFFSET(frames_str),AV_OPT_TYPE_STRING,{.str = NULL},  0, 0,       E },
>> +    { "segment_chapters",  "split segments on chapter markers",          OFFSET(split_chapters), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
>>     { "segment_wrap",      "set number after which the index wraps",     OFFSET(segment_idx_wrap), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },
>>     { "segment_list_entry_prefix", "set base url prefix for segments", OFFSET(entry_prefix), AV_OPT_TYPE_STRING,  {.str = NULL}, 0, 0, E },
>> -    { "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_start_number", "set the sequence number of the first segment", OFFSET(segment_idx), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 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_BOOL, {.i64 = 0 }, 0, 1, E },
>> diff --git a/libavformat/version.h b/libavformat/version.h
>> index a8cf4c1..4d12f5b 100644
>> --- a/libavformat/version.h
>> +++ b/libavformat/version.h
>> @@ -33,7 +33,7 @@
>> // Also please add any ticket numbers that you believe might be affected here
>> #define LIBAVFORMAT_VERSION_MAJOR  57
>> #define LIBAVFORMAT_VERSION_MINOR  77
>> -#define LIBAVFORMAT_VERSION_MICRO 100
>> +#define LIBAVFORMAT_VERSION_MICRO 101
>> 
>> #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
>>                                                LIBAVFORMAT_VERSION_MINOR, \
>> --
>> 2.6.4
>> 
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