How should #EXT-X-MEDIA-SEQUENCE be updated for Iframe Only playlist that use byte ranges?

Question

Created Jun ’15

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For the EXT-X-MEDIA-SEQUENCE tag, the specification states:

"The EXT-X-MEDIA-SEQUENCE tag indicates the Media Sequence Number of the first Media Segment that appears in a Playlist file."

But for Iframe Only playlist that use the EXT-X-BYTERANGE tag and mark multiple Iframes in a single segment, how should the EXT-X-MEDIA-SEQUENCE tag be update? Should this be incremented based on the TS segment that the byte ranges describes or should it be updated to match the total number of EXT-X-EXTINF tags that have been encountered (i.e. The number of Iframes)?

Example:

Initial Iframe-Only playlist

#EXTM3U
#EXT-X-VERSION:4
#EXT-X-I-FRAMES-ONLY
#EXT-X-TARGETDURATION:7
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:2.010
#EXT-X-BYTERANGE:8648@376
test/segment_0.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:16920@49256
test/segment_0.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:13724@150776
test/segment_0.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:8648@376
test/segment_1.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:12220@57904
test/segment_1.ts
#EXTINF:2.010
#EXT-X-BYTERANGE:13348@130472
test/segment_1.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:4512@376
test/segment_2.ts
#EXTINF:4.000
#EXT-X-BYTERANGE:11092@42864
test/segment_2.ts

After the first segment scrolls off the top of the playlist, what should the media sequence number be?

#EXTM3U
#EXT-X-VERSION:4
#EXT-X-I-FRAMES-ONLY
#EXT-X-TARGETDURATION:7
#EXT-X-MEDIA-SEQUENCE:1|3              <-- Should this be 1 for the media segment OR 3 for the number of Iframes?
#EXTINF:2.000
#EXT-X-BYTERANGE:8648@376
test/segment_1.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:12220@57904
test/segment_1.ts
#EXTINF:2.010
#EXT-X-BYTERANGE:13348@130472
test/segment_1.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:4512@376
test/segment_2.ts
#EXTINF:4.000
#EXT-X-BYTERANGE:11092@42864
test/segment_2.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:5264@376
test/segment_3.ts
#EXTINF:2.010
#EXT-X-BYTERANGE:15792@57340
test/segment_3.ts
#EXTINF:2.000
#EXT-X-BYTERANGE:20116@123516
test/segment_3.ts

I've looked for examples in the Pantos specification and on the Apple developer site and haven't been able to find anything on this. I've also checked the mediafilesegmenter and that doesn't seem to support generation if Iframe-Only playlists.

Any help you could provide would be greatly appreciated.

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Answer 1

Media Engineer OP

Apple

Jun ’15

The EXT-X-MEDIA-SEQUENCE should be 3.

You count based on URL lines, not on unique URLs.

(Per draft-pantos-http-live-streaming-16 section 4.3.2 "Each Media Segment is specified by a series of Media Segment tags followed by a URI.")

mediafilesegmenter does support the generation of I-frame playlists (see the --iframe-index-file option).

0

Answer 2

baleighsdad OP

Jul ’15

mediafilesegementer will generate i-frame playlists by default.

0