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       HLS-24: Encode fails where audio stream present but null

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Issue Type: Bug 
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Issue Information
====================

Priority: Major					Status:      Closed
Resolution:  Done (2019-07-26 13:17:37)
Project: HLS Stream Creator (HLS)


Reported By: btasker					
Assigned To: btasker

Components: 
	- Transcoding 

Affected Versions:		
	- 1.0  			


Targeted for fix in version: 
	- 1.0

Labels: Audio, 

Time Estimate: 45 minutes
Time Logged:   0 minutes


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Issue Description
==================

HLS Stream creator will fail to run where an audio stream is present but shows as type
none

-- BEGIN SNIPPET --

  Duration: 00:00:00.00, start: 4241.278000, bitrate: N/A
    Stream #0:0: Video: flv1, 1 reference frame, yuv420p, 1280x720, 199 kb/s, 8.33 tbr, 1k
tbn, 1k tbc
    Stream #0:1: Audio: none, 0 channels

 -- END SNIPPET --

The resulting error is

-- BEGIN SNIPPET --

  Duration: 00:00:00.00, start: 4241.278000, bitrate: N/A
    Stream #0:0: Video: flv1, 1 reference frame, yuv420p, 1280x720, 199 kb/s, 8.33 tbr, 1k
tbn, 1k tbc
    Stream #0:1: Audio: none, 0 channels
[graph 0 input from stream 0:0 @ 0xace980] w:1280 h:720 pixfmt:yuv420p tb:1/1000 fr:25/3
sar:0/1 sws_param:flags=2
No decoder for stream #0:1, filtering impossible
Error opening filters!
Invoking deleteStream

 -- END SNIPPET --

This can be mitigated by setting an FFMPEG flag to tell ffmpeg to ignore the audio
stream:

-- BEGIN SNIPPET --

ben@milleniumfalcon:/tmp/HLSCreate$ FFMPEG_FLAGS="-an"
ben@milleniumfalcon:/tmp/HLSCreate$ export FFMPEG_FLAGS
ben@milleniumfalcon:/tmp/HLSCreate$ ./HLS-Stream-Creator.sh -l -i
rtmp://ent1/camtest/camera -s 2

 -- END SNIPPET --

But it'd be nice to have a commandline flag to be able to do this

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Issue Relations
================
	
	- relates to HLS-25: Additional flags/features to aid Low Latency Streaming


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Activity
==========

	
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2019-07-26 13:09:25              git
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-- BEGIN QUOTE --


Repo: HLS-Stream-Creator
Commit: db85e45814b2a163c5ae927bca36a74460483fe7
Author: B Tasker <github@<Domain Hidden>>

Date: Fri Jul 26 13:03:02 2019 +0100
Commit Message: HLS-24 Allow audio track to be ignored with the -n commandline argument

This forces -an to be passed to ffmpeg.

It's not generally required, as missing audio tracks will be handled by default, but this
allows the user to address inputs where `ffmpeg` reports the Audio type as `none`:

-- BEGIN SNIPPET --

    Stream #0:0: Video: flv1, 1 reference frame, yuv420p, 1280x720, 199 kb/s, 8.33 tbr, 1k
tbn, 1k tbc
    Stream #0:1: Audio: none, 0 channels

 -- END SNIPPET --
This test stream was the result of a webcam being published into an RTMP relay with FFMPEG
and then pulled back out the other side.



Modified (-)(+)
-------
HLS-Stream-Creator.sh
README.md



-- END QUOTE --

*Webhook User-Agent*


-- BEGIN SNIPPET --

GitHub-Hookshot/20c7c42
 -- END SNIPPET --

https://github.com/bentasker/HLS-Stream-Creator/commit/db85e45814b2a163c5ae927bca36a74460483fe7


	
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2019-07-26 13:17:17              btasker
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Commit db85e4 implements a new commandline flag -n 

When this flag is present in the HLS-Stream-Creator commandline, we'll pass ffmpeg the
flag -an in order to disable audio.

This leads to a slightly odd (but fine) ffmpeg command, in that we specify the audio codec
to use, and then disable audio anyway. 

-- BEGIN SNIPPET --

ffmpeg -i ~/How_to_Build_a_Cathedral--.mp4 -y -vcodec libx264 -acodec aac -threads 0 -map
0 -flags -global_header -f segment -segment_list
./output/How_to_Build_a_Cathedral--.mp4.m3u8 -segment_time 10 -segment_format mpeg_ts -an
./output/How_to_Build_a_Cathedral--.mp4_%05d.ts

 -- END SNIPPET --
It's a little odd looking but doesn't cause any harm, so it seems foolish to introduce
additional complexity to remove arguments from a command the user will never routinely see
anyway.

	
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2019-07-26 13:17:30              
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btasker added 'Audio' to labels
	
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2019-07-26 13:17:37              
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btasker changed status from 'Open' to 'Resolved'
	
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2019-07-26 13:17:37              
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btasker added 'Done' to resolution
	
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2019-07-26 13:17:41              
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btasker changed status from 'Resolved' to 'Closed'