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       HLS-14: General Testing Notes

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Issue Type: Informational 
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Issue Information
====================

Priority: Major					Status:      Open
Resolution:  Unresolved
Project: HLS Stream Creator (HLS)


Reported By: btasker					
Assigned To: 



Targeted for fix in version: 
	- VNEXT

Labels: Testing, 

Time Estimate: 0 minutes
Time Logged:   0 minutes


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Issue Description
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Container issue for notes from general playback testing

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Issue Relations
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	- Discovered HLS-15: Append #EXT-X-ENDLIST when a live stream concludes


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Activity
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2015-06-15 16:13:22              btasker
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Testing with revision _55d3a7e_

Playing back a stream being read from a named pipe

-- BEGIN SNIPPET --

./HLS-Stream-Creator.sh -i /tmp/test.fifo.avi -s 2 -o /tmp/fifotest/ -l -b 1024 -c 15

 -- END SNIPPET --
Playback on 3 devices

- PC (via loopback) in VLC
- Android tablet (Wifi) in MX Player
- RaspBMC (copper ethernet)

The PC occasionally sticks and/or briefly drops audio where the other devices do not. It's
possible it's related to the delivery speeds achieved over the loopback - it is
consistently ahead of the other devices. Tweaking segment length and count may address
that.

The Tablet (wifi) pauses occasionally, but recovers. So far, doesn't appear to have
dropped audio. The wifi on that tablet can be a little iffy at times, so it's possible
it's more of a delivery issue than an encoding issue.

XBMC is playing consistently without issue, it's a little ahead (couple of seconds, so 1
segment) of the tablet and probably around half a segment behind the PC.

So the issues seen on the PC and the tablet are probably related to the speed at which
segments are delivered.

It shouldn't be possible for the PC to get ahead though, as it should start from the
beginning of the manifest. Might need to look at little closer at _vlc_s behaviour and
test with another player (_mplayer_?) to see whether the behaviour is still observed.


One issue on RaspBMC is that it doesn't like it (hangs) when a live manifest comes to an
end. It seems _ffmpeg_ isn't appending _#EXT-X-ENDLIST_ once the input stream is complete,
so we'll need to look at appending that ourselves (but only for live streams) - HLS-15 .
	
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2015-06-15 16:16:09              
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btasker added 'Testing' to labels
	
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2015-06-15 17:23:59              btasker
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Testing with revision 55d3a7e

-- BEGIN SNIPPET --

$ ./HLS-Stream-Creator.sh -i /tmp/test.fifo.avi -s 2 -o /tmp/fifotest/ -l -b 1024 -c 15

 -- END SNIPPET --
One concern for linear streams, _ffmpeg_ doesn't appear to take into account that it may
be ahead of the player and that the player will take _SEGLENGTH_ seconds (so 2 seconds
above) to progress through each segment.

As a result, if the encodes happen quickly (i.e. in less than 2 seconds), the sliding
window bumps content off the beginning of the manifest before the player has played them,
leading to the video and audio jumping (so far, usually by a single segment).

Using a longer sliding window will probably briefly address this, but it's only really
extending the time before the issue occurs. It doesn't seem to consistently happen
(suggesting _ffmpeg_ is getting through some segments much faster than others).

It doesn't break playback, but can make it a little uncomfortable to watch. 

Given that project HLSDVD will be entirely concerned with pushing live streams, it's
something that going to need to be addressed - having a long manifest won't be an
acceptable solution because user-input (such as a press on the remote control) needs to be
reflected on the output stream within a reasonable timeframe (likely within a second...)
	
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2019-11-23 12:09:19              
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btasker added 'VNEXT' to Fix Version
	
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2019-11-23 12:09:19              
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btasker removed '1.0' from Fix Version