[FFmpeg-trac] #6533(avformat:reopened): Invalid EXT-X-TARGETDURATION in HLS
FFmpeg
trac at avcodec.org
Thu Aug 10 10:28:57 EEST 2017
#6533: Invalid EXT-X-TARGETDURATION in HLS
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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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Changes (by tonn81):
* status: closed => reopened
* resolution: wontfix =>
Comment:
I would disagree with @stevenliu -- result generated by ffmpeg is not what
is expected -- `TARGETDURATION` does not match the value given as
`--hls_time`.
Actually, there are two bugs in ffmpeg. Together they give this false
result.
Here are the bugs:
1. **ffmpeg generate HLS chunks with duration that does not match given
`--hls_time`**
ffmpeg should generate chunks not longer than given with `--hls_time`.
For `--hls_time 4` it generated `4.02` chunk instead of `4.0` or less.
2. **ffmpeg converts chunk duration into `EXT-X-TARGETDURATION`
incorrectly**
According to official HLS validator (`mediastreamvalidator`), there
could be 25% difference between actual chunk size and value. That means we
should not ceil the value but rather round to nearest integer (so that
delta between maximum chunk duration and `TARGETDURATION` is minimal).
Then `4.02` would become `4`, not `5`.
I could file another bug report for HLS chunks generation if needed.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/6533#comment:4>
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