DASH

Some things are hidden for a reason, and if you see them, you'll be changed forever, but I wanted to be changed forever.

Miranda July

• https://f002.backblazeb2.com/file/minerals/ISO_IEC_23009-1_2022(en).pdf
• https://wikipedia.org/wiki/Dynamic_Adaptive_Streaming_over_HTTP
• https://dashif.org/Guidelines-TimingModel/Timing-Model.pdf
• https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf

Go language, I need a package for DASH (MPD) files

1. standard library only
2. use a separate file for each type
3. only send new or updated files
4. package is named "dash"
5. package will include a parse method, byte slice input
6. BaseURL is a single element not a slice
7. support these elements and attributes
   • MPD
     • @mediaPresentationDuration
     • BaseURL
     • Period
       • @duration
       • @id
       • BaseURL
       • AdaptationSet
         • @codecs
         • @height
         • @lang
         • @mimeType
         • @width
         • ContentProtection
           • @schemeIdUri
           • cenc:pssh
         • Role
           • @value
         • SegmentTemplate
           • @duration
           • @endNumber
           • @initialization
           • @media
           • @presentationTimeOffset
           • @startNumber
           • @timescale
           • SegmentTimeline
             • S
               • @d
               • @r
         • Representation
           • @bandwidth
           • @codecs
           • @height
           • @id
           • @mimeType
           • @width
           • BaseURL
           • SegmentTemplate
           • ContentProtection
           • SegmentBase
             • @indexRange
             • Initialization
               • @range
           • SegmentList
             • Initialization
               • @sourceURL
             • SegmentURL
               • @media
8. add navigation
   1. from AdaptationSet to Period
   2. from Initialization to SegmentList
   3. from Period to MPD
   4. from Representation to AdaptationSet
   5. from SegmentList to Representation
   6. from SegmentTemplate to AdaptationSet
   7. from SegmentTemplate to Representation
   8. from SegmentURL to SegmentList
9. resolve BaseURL using
   1. MPD URL
   2. all parent BaseURL
10. resolve Initialization@sourceURL using
11. MPD URL
12. all parent BaseURL
13. resolve SegmentTemplate@initialization using
14. MPD URL
15. all parent BaseURL
16. resolve SegmentTemplate@media using
17. MPD URL
18. all parent BaseURL
19. resolve SegmentURL@media using
20. MPD URL
21. all parent BaseURL
22. resolve function should return *url.URL
23. add method to get all Representation, group by id
24. add method to get codecs
25. add method to get height
26. add method to get width
27. add method to get mimeType
28. AdaptationSet.Role is single element not slice
29. add method to get SegmentTemplate
30. add method to replace SegmentTemplate@initialization

• $RepresentationID$

23. add method to replace SegmentTemplate@media

• $Number$
• $Number%02d$
• $Number%03d$
• $Number%04d$
• $Number%05d$
• $Number%06d$
• $Number%07d$
• $Number%08d$
• $Number%09d$
• $RepresentationID$

24. add method to replace SegmentTemplate@media

• $RepresentationID$
• $Time$

25. SegmentTemplate@startNumber is 1 if missing
26. SegmentTemplate@timescale is 1 if missing
27. Period@duration is MPD@mediaPresentationDuration if missing
28. add method to get Time values from SegmentTimeline
29. add method to get Number values from SegmentTimeline
30. add method to get Number values from SegmentTemplate@startNumber to SegmentTemplate@endNumber
31. add method to get Number values from Ceil( AsSeconds(Period@duration) / (SegmentTemplate@duration / SegmentTemplate@timescale) )
32. add a method that returns the SegmentTemplate URLs
33. use SegmentTemplate@presentationTimeOffset as initial $Time$
34. add method to get time.Duration

    time.ParseDuration(strings.ToLower(
       strings.TrimPrefix(Period@duration, "PT"),
    ))
    

35. add method to get unique ContentProtection from

• AdaptationSet
• Representation

36. include test file in same package

• test will read all ".mpd" files in the "testdata" folder
• user will provide test files
• for each file, get the slice of replaced SegmentTemplate@media URLs
• only get one slice of URLs per mimeType
• print slice length, and first and last URLs

37. add Representation.String method. each value on its own line
38. Representation@bandwidth
39. Representation.GetWidth
40. Representation.GetHeight
41. Representation.GetCodecs
42. Representation.GetMimeType
43. AdaptationSet@lang
44. Role@value
45. Period@id
46. Representation@id

contact

email

[email protected]

Discord username

10308