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I'm currently trying to use FFMpeg to capture my webcam , output it to dash and stream it live. I noticed that the "availabilityStartTime" parameter created in the MPD file is without the milliseconds part.

availabilityStartTime="2018-12-31T14:47:13Z"

I noticed that the ffmpeg library use "get_utc_date_time_insec" to fill the availabilityStartTime in the MPD file.

Is there a way for ffmpeg to fill the availabilityStartTime with complete timestamp?

Thank you

Shachar Levy
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    Not implemented, but it could be added to the code. But why would you need such precision here? – slhck Dec 31 '18 at 15:43
  • ffmpeg is using ISO-8601 format for date time. Although not specified anywhere in the DASH spec (ISO 23009), all examples use the 8601 format. So it's unlikely that this would be changed. – Gyan Dec 31 '18 at 16:23
  • We need this information to be as precised as possible as we count on the availabilityStartTime for synchronization between two live streams. – Shachar Levy Jan 01 '19 at 09:15
  • @Gyan DASH uses XML's `xs:dateTime` for timing, which *can* use millisecond precision. But it's unlikely that this is needed in practice. – slhck Jan 01 '19 at 12:25
  • @slhck I agree with you , however we do have a case where the extra milliseconds data is important for us. If the Dash spec does not conflict with the ffmpeg implementation (meaning that the complete timestamp can be used) , why not adding it? – Shachar Levy Jan 01 '19 at 12:37
  • Sure, I agree it wouldn't hurt to have if the spec allows it, but as I'm not a core FFmpeg developer, I don't know if changing the assumption that these timings can have millisecond precision carries all sorts of other changes with it. In principle you could patch the function `format_date_now` in `dashenc.c` to return milliseconds. – slhck Jan 01 '19 at 12:46
  • @slhck thank you , we did a custom patch to ffmpeg like you said and its working now – Shachar Levy Jan 24 '19 at 09:04
  • For anyone that may be interested in this feature too , It's already in FFMPEG main. - https://github.com/FFmpeg/FFmpeg/commit/b6d96a6bcc531c216623fbcdf9d5034f51abf216#diff-bb639d36d2c5d7cdcefacb6273d80d1f – Shachar Levy Feb 27 '19 at 07:16

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