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HLS stream works fine in html5 mode but not in the flash mode

Our backend works with videos that have already been split into chunks. We process each of those chunks with ffmpeg to produce different bitrate streams and then stream them via HLS. Streams that we created with some certain ffmpeg params work fine - videos are played nicely. But for other sets of ffmpeg params we encountered a problem - JwPlayer plays fine in html5 mode, but glitches in flash mode (it skips parts of the video). We checked a number of other flash players and they seem to work fine with those videos. We can`t figure out what seems to be the problem with flash version of JwPlayer.

The example of our stream that works fine in both html5 and flash modes: http://dev-api.pov.la/api/video/sC3/6y4kehK/playlist.m3u8
This video was encoded with the following ffmpeg params:
-acodec copy -vcodec libx264 -copyts -mpegts_copyts 1 -vf "scale=480:-1, fps=30000/1001" -vb 200000 [path].ts

The example of our stream that works fine only in html5 mode: http://dev-api.pov.la/api/video/aC3/6y4kehK/playlist.m3u8
You can see that video plays fine up to a beginning of a 4th second, and then jumps on the 8th second.
FFmpeg params for this video:
-acodec libvo_aacenc -ab 32k -ac 1 -vcodec libx264 -copyts -mpegts_copyts 1 -vf "scale=320:-1, fps=10000/1001" -vb 55000 -bf 0 [path].ts

Can you please point out, what is wrong with our stream?

3 Community Answers

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Cooper Reid

JW Player Support Agent  
0 rated :

Can you try using the parameters used in the first stream to created the second? If they worked fine, I would definitely recommend sticking with them.

Also, we recommend that your segment durations are around 10 seconds each, and that keyframing is done every 4 seconds.

Kind Regards,
Cooper
Client Support Engineer, JWPlayer

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DSorokin

User  
0 rated :

Sorry, I haven`t claryfied this right away: those streams created from the same set of source video chunks, so applying first set of params to a second stream would definitely work. The thing is, first stream meant to be middle bitrate stream, and second - low bitrate. In the first case we can afford 30000/1001 fps (the same as in the source), and in second case we can`t, so we use fps=10000/1001. Among the other params fps is probably the one that causes the problem. But we need to use low fps, so we have to find out what the actual problem is.
Btw, can audio encoding cause that sort of problem?

I will investigate our ffmpeg params a little bit further on monday, and try to find out what exact param fails our stream. I`ll let you know right away.

Up Down

Cooper Reid

JW Player Support Agent  
0 rated :

Not sure I’m following the fps discussion. You can test any of your stream here: http://demo.jwplayer.com/hls-tester

Also, it is possible that audio encoding could cause issues to the player – please make sure the audio encoding follows the standards defined on this page: http://support.jwplayer.com/customer/portal/articles/1403635-media-format-reference#video

-Cooper

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