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bkgoodman's avatar
bkgoodman
Visitor
15 years ago

HLS Playback of more than 5 Fragments fails

A am in the process of developing a "channel" - and am creating some test content to test my streaming/encoding workflow, and am running into some issues. Due to the nature of what I am seeing, it doesn't seem like it is a problem in the encoding as so much as a problem with Roku...
I am following all Roku's guidelines on the encoding format, and am having minimal success as follows:

I create a video, and fragment it as required. (10 Second fragments, 380x360, 800k/bps, 23.98fps, etc. etc.)

When I go to play the video, the "Recieving" bar would start to fill up, then stop - without ever playing the video. As I susspected there might be a problem later in the video, I edited my m3u8 file to trim down the video (remove fragments from the end). When I got it down to about 5 fragments, the video played just fine.

So I figured there must be some problem with the 6th fragment, etc. I tried a lot with re-encoding, etc, never resolved the issue. Then I tried the following:

If I list the *same* fragment around 5 times - the video will play back properly. However, If I play the *same* fragment back more than 5 times, the playback gets stuck on "Recieving".

In experimenting further - I find that I can specify any 5 fragments and the playback will work. If I specify more than 5, playback will never properly start.

Any idea what the issue could be??

Brad Goodman
SeaChange International
Roku Developer Program

12 Replies

  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    I tried to re-encode video using exact settings listed in Roku encoding guide, and had no luck. In fact - it may have even gotten a little worse. (It only appears to now play 4 fragments before failing).

    My test videos are simply a series of PNG files which are being encoded to an H264/MPEGTS stream, using FFMPEG, as specified in the encoding guide.
  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    Thanks a ton!

    I put some abbreviated test samples on a public server which demonstrate the issue:

    I have 4 .ts files (call them frag1-frag4 for the sake of converstaiton), and created 3 different manifests which all use these same files to demonstrate the issue.

    The manifest at:
    http://www.bradgoodman.com/HLSTest3/appleTest3.m3u8
    Will play fragments 1-4. This should work, but doesn't. It will work from my iPhone.

    The manifest at:
    http://www.bradgoodman.com/HLSTest3/appleTest2.m3u8
    Will play frament1 three times. (You'll be able to see the counter reset around 10 seconds, when the first fragment repeats - this will happen twice). This test will play correctly on the Roku box.

    The manifest at:
    http://www.bradgoodman.com/HLSTest3/appleTest.m3u8
    Is just like appleTest2 (above), but repeats the first fragment four times, as opposed to three. This test will not play at all.

    Thanks for all the help!

    -BKG
  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    One more "hint":

    Although the video does not begin to play - if a longer video is actually specified - the Roku box will continue to attempt to read the rest of the fragments of the video.

    This is done in somewhat quick succession - i.e. fragments are read about a half-second apart - like is done when initially prefetching the video - not every 10 seconds apart, as it was normally playing.
  • RokuMarkn's avatar
    RokuMarkn
    Visitor
    15 years ago
    Each of these URLs contains a single fragment, at least when I just looked at them. Are these changing dynamically?

    --Mark
  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    Each of these files contain a reference to a single program at a single bitrate. For example, the file:

    http://www.bradgoodman.com/HLSTest3/appleTest2.m3u8

    Contains the following:


    #EXTM3U
    #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=737777
    prog_index2.m3u8


    Which indicates the program "prog_index2.m3u8" (which is a relative reference to the file at http://www.bradgoodman.com/HLSTest3/prog_index2.m3u8.) This is the file which contains the actual fragment list, which (in this example) is:


    #EXTM3U
    #EXT-X-TARGETDURATION:10
    #EXT-X-MEDIA-SEQUENCE:0
    #EXTINF:10, no desc
    HLStest3-1.ts
    #EXTINF:10, no desc
    HLStest3-1.ts
    #EXTINF:10, no desc
    HLStest3-1.ts
    #EXT-X-ENDLIST


    ..which lists the actual three fragments. This example is from the video that actually works.

    Thanks for your help!

    -BKG
  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    Tested these videos with Boxee (both Boxee box and Windows client) - everything worked fine (as they also do with iPhone and iPad).

    -BKG
  • RokuKevin's avatar
    RokuKevin
    Visitor
    15 years ago
    I'm getting different results than you did... If you haven't done so, Please update to v3.0.

    http://www.bradgoodman.com/HLSTest3/appleTest3.m3u8
    Plays fine. (Only plays for 10 seconds)

    The manifest at:
    http://www.bradgoodman.com/HLSTest3/appleTest2.m3u8
    Plays fine. (Only plays for 10 seconds).

    The manifest at:
    http://www.bradgoodman.com/HLSTest3/appleTest.m3u8
    Doesn't play at all, and I get warnings about:
    "expecting start of section: discard 184 video bytes"

    How were the transport stream files created?

    --Kevin
  • bkgoodman's avatar
    bkgoodman
    Visitor
    15 years ago
    I retried my tests (with the same videos on the same servers) - and got the same results.

    I upgraded to 3.0.2202 then tried the tests again, and got the same results. "appleTest" fails, "appleTest2" plays, and "appleTest3" fails.

    Could you double-check your results?

    * We both agree "appleTest" should fail
    * You said "appleTest2" played for 10 second - I say it should play for 30 seconds. (Please see below)
    * You said "appleTest3" played, whereas for me it failed.

    RE: appleTest2:

    When you say the video "only plays for ten seconds" - does it really?

    The videos should play the first fragment three times. So if your just looking at the counter - and not paying attention - you might miss the fact that is has repeated.

    Also - where do you see the error message you spoke of? I do not see any.

    I encoded these videos from a series of still PNG files, using FFMPEG, exactly as specified in the "Roku Encoding Guide".

    Thanks for your help!