[FFmpeg-trac] #6533(avformat:reopened): Invalid EXT-X-TARGETDURATION in HLS

[FFmpeg]

#6533: Invalid EXT-X-TARGETDURATION in HLS
-------------------------------------+------------------------------------
             Reporter:  tonn81       |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:  avformat
              Version:  unspecified  |               Resolution:
             Keywords:  hls          |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by stevenliu):

 Replying to [comment:12 tonn81]:
 > OK, let me be more specific.
 >
 > Specification says this rule must be followed:
 >
 >     `all {round(chunk_duration) <= EXT_X_TARGETDURATION}`
 >
 > In current implementation, we have:
 >
 >     `EXT_X_TARGETDURATION = ceil(max{chunk_duration})`
 >
 >     It gives result that matches the specification (part about `less`)
 but not precise.
 >
 > I suggest to have:
 >
 >     `EXT_X_TARGETDURATION = round(max{chunk_duration})`
 >
 >     It gives result that matches the specification (part about `equal`)
 and precise.
 >
 >     Also, that aligns with the value that user provided as input to
 ffmpeg (`-hls_time`) and allows to ignore small difference that HLS
 segmenter generates (e.g. `4.02` instead of `4.0`).
 >
 > Current implementation:
 >
 > {{{
 >     for (en = hls->segments; en; en = en->next) {
 >         if (target_duration <= en->duration)
 >             # that would actually ceil
 >             target_duration = get_int_from_double(en->duration);
 >     }
 > }}}

 That is not ceil:

 static int get_int_from_double(double val)
 {
     return (int)((val - (int)val) >= 0.001) ? (int)(val + 1) : (int)val;
 }

 or can you reproduce the bug of the EXT_X_TARGETDURATION *LESS* than
 en->duration ?

 >
 > Suggested implementation (pseudo-code):
 >
 > {{{
 >     for (en = hls->segments; en; en = en->next) {
 >         if (target_duration < en->duration)
 >             # if chunk duration is bigger than target duration -- round
 it and use it,
 >             # it could be also the same value as target_duration if
 rounded to lower value
 >             target_duration = (int)round(en->duration);
 >     }
 > }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/6533#comment:13>
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