Playback stutters, #EXT-X-DISCONTINUITY on every segment

[Jamedjo]

I'm feeding video files in on rtmp through ffmpeg and outputting hls. It plays fine on desktops but stutters when changing segment on iphone 4 and some android tablets. If I remove the #EXT-X-DISCONTINUITY tags and serve the files from a static location it works fine on ios.

Should these only appear when a new video is played through rtmp? How do I prevent #EXT-X-DISCONTINUITY tags appearing between every segment?

PS. Compiled using dev branch to support Nginx 1.11

[Jamedjo]

Had the same issue on master with nginx 1.8.1.

Setting -r 24 -x264opts keyint=24:min-keyint=24:scenecut=-1 gets rid of the DISCONTINUITY tags and fixes each EXTINF to 5.000 instead of varying significantly. Playback is much smoother, but unfortunately now cuts when changing quality on iOS. Could this be because the audio and video lengths don't match? How should I go about debugging this?

[Jamedjo]

It doesn't cut out on every hls_variant switch: most of the time it is fine, about once every 2m it will stutter and once every 10m cut out. When it stutters or cuts out the nginx log shows Client prematurely closed connection while sending response to client.

[DavidVentura]

I'm getting the same thing on master branch with nginx 1.9.11.

[DavidVentura]

Jamedjo would you please post your entire ffmpeg options? I keep getting the DISCONTINUITY tags.

movie.m3u8
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:11
#EXT-X-TARGETDURATION:15
#EXT-X-DISCONTINUITY
#EXTINF:9.985,
movie-11.ts
#EXT-X-DISCONTINUITY
#EXTINF:9.985,
movie-12.ts

[chriswiggins]

Can you guys please try adding the hls_continuous off; option into your config and see if this helps?

[DavidVentura]

That's the default and is not set on my server

[Jamedjo]

Had compiled our own ffmpeg (3.0.2) while attempting to use libfdk_aac, and used roughly the command below:

exec /usr/local/bin/ffmpeg -i rtmp://localhost:1935/live/livestream -c:v libx264 -vprofile baseline -r 24 -x264opts keyint=24:min-keyint=24:scenecut=-1 -sc_threshold 0 -b:v 800k -c:a aac -strict -2 -b:a 128k -tune zerolatency -preset veryfast -f flv rtmp://localhost/hls/livestream_high

I've just added hls_continuous off; and will see if that helps the Could not load movie iOS errors

[Jamedjo]

Line I'd uncommented was actually hls_continuous on;, but this didn't fix it. Also tried set to off, but had the same error after 7mins.

[DavidVentura]

To test I use this: https://dailymotion.github.io/hls.js/demo/

It shows if there's discontinuity I haven't been able to fix it yet here. I don't know what might be it. These are my ffmpeg params

ffmpeg -i rtmp://localhost/rpi/$name -c:v libx264 -threads 4 -preset slow -r 24 -x264opts keyint=24:min-keyint=24:scenecut=-1 -g 48 -b:v 450k -bufsize 900k -vf "movie=/root/logo_videos.png [watermark]; [in][watermark] overlay=(main_w-overlay_w-10):(main_h-overlay_h-30) [out]" -c:a copy -f flv rtmp://localhost:1935/s2/$name 2>>/var/log/ffmpeg-$name.log;

This works on rtmp but breaks on hls

[Jamedjo]

The keyint settings are an alternative to -g, so probably shouldn't use both, or at least set them the same. http://superuser.com/questions/908280/what-is-the-correct-way-to-fix-keyframes-in-ffmpeg-for-dash

[DavidVentura]

This is what the discontinuity looks like. Grey is video, black is the discontinuity that shouldn't be here

[DavidVentura]

For now I'm using only the rtmp side of this and for hls I'm using ffmpeg.

ffmpeg -i rtmp://localhost/src/movie -c copy -flags -global_header -map 0 -bsf:v h264_mp4toannexb -hls_time 6 -hls_list_size 5 -hls_wrap 25 test.m3u8

[Jamedjo]

Does using ffmpeg for hls fix it? Was it easy to use for live broadcasts or was there additional setup?

[DavidVentura]

I literally run that command on exec_push and it works (well, its inside a .sh but it's the same).

I haven't really thought about doing level switching with it (it doesn't do automatically) but it already outputs in 2 qualities with:

#!/bin/sh

commonOpts="-flags -global_header -map 0 -bsf:v h264_mp4toannexb -hls_time 6 -hls_list_size 5 -hls_wrap 25"
cd /tmp/hls/
ffmpeg  -i rtmp://localhost/src/movie \
    -c copy $commonOpts /tmp/hls/movie.m3u8 \
    -c:a copy -c:v libx264 -s 360x270 -r 10 -g 20 -preset veryfast $commonOpts /tmp/hls/low.m3u8