Errors when using ABR DASH

Corey 2015-08-29 02:49:54 UTC in Nimble Streamer

I received an error as below, and the video would freeze. I have no idea how to fix this issue.
[tmux] E: catched DashTransmuxingException while processing file='xxx/video.mp4' chunk_name='v_0_858624.m4s' msg='wrong segment index'

I setup nimble in my Macbook and use FFMPEG to generate 3 different resolution videos ( 1280*720, 1138*640, 640*360) by commands as below.
ffmpeg -y -i Original.mp4 -c:a libvo_aacenc -ac 2 -ab 128k -c:v libx264 -r 30 -g 30 -b:v 1500k -maxrate 1500k -bufsize 1000k -vf "scale=-1:720" _720p.mp4
ffmpeg -y -i Original.mp4 -c:a libvo_aacenc -ac 2 -ab 128k -c:v libx264 -r 30 -g 30 -b:v 1000k -maxrate 1000k -bufsize 800k -vf "scale=-1:640" _640p.mp4
ffmpeg -y -i Original.mp4 -c:a libvo_aacenc -ac 2 -ab 128k -c:v libx264 -r 30 -g 30 -b:v 400k -maxrate 400k -bufsize 400k -vf "scale=-1:360" _360p.mp4

SMIL
<?xml version="1.0" encoding="UTF-8"?>
<smil title="">
<body>
<switch>
<video src="xFaire_720p.mp4" systemLanguage="eng">
<param name="videoBitrate" value="1500000" valuetype="data"></param>
<param name="audioBitrate" value="44100" valuetype="data"></param>
</video>
<video src="xFaire_640p.mp4" systemLanguage="eng">
<param name="videoBitrate" value="1000000" valuetype="data"></param>
<param name="audioBitrate" value="44100" valuetype="data"></param>
</video>
<video src="xFaire_360p.mp4" systemLanguage="eng">
<param name="videoBitrate" value="400000" valuetype="data"></param>
<param name="audioBitrate" value="44100" valuetype="data"></param>
</video>
</switch>
</body>
</smil>

Corey 2015-08-29 03:03:04 UTC

looks like the issue can be solved by disabling to use b-frame

Yury Udovichenko 2015-08-29 04:29:45 UTC

Hi,

Thanks for sharing the solution.

Alex Pokotilo 2015-08-30 08:28:35 UTC

ABR force you to have key frames in the same time for all your renditions so all streams should be key-frame aligned.
With ffmpeg you should use keyint and min-keyint params to force keyframe insertion every N frames. For example with 25 fps you can force to insert keyframe every 1 second settings keyint=25 and
min-keyint=25
see http://superuser.com/questions/908280/what-is-the-correct-way-to-fix-keyframes-in-ffmpeg-for-dash
http://stackoverflow.com/questions/14117757/how-to-control-key-frame-generation-of-ffmpeg

Corey 2015-09-03 08:29:32 UTC

Thanks Alex for the solution. As mentioned in the reference link, -g argument might be deprecated. Instead, we can use keyint and min-keyint to control keyframe insertion just like Alex said. And so far it works well.
Forget about disabling to use b-frame I said before.

Alex Pokotilo 2015-09-03 08:31:53 UTC

Thanks for reporting

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