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There are 2 problems with using Viblast to play HLS Live stream

My index.m3u8 file is defined as follows.

720p segment file is 10 seconds, 540p and 360p of the segment file is 2 seconds.

 

#EXT-X-STREAM-INF:BANDWIDTH=2501251,CODECS="avc1.77.31,mp4a.40.2",RESOLUTION=1280x720
chunklist_source/chunklist.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1236421,CODECS="avc1.77.31,mp4a.40.2",RESOLUTION=960x540
chunklist_540p/chunklist.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=483294,CODECS="avc1.77.30,mp4a.40.2",RESOLUTION=640x360
chunklist_360p/chunklist.m3u8

  

When I use Viblast to play the above HLS Live Stream, the following two questions.

1, Viblast first time to load the video always choose the middle quality (540p) for playback,

Is this an existing problem?

My network is very good, and can smooth playback of high quality video.

 

2, when I switch from low to high quality for quality selection, the video will be backwards.

I think when Viblast switch quality playback, there is no correct match to the currently playing frame, and select the current frame after the video to play.

Is this an existing problem?


Hi CharlesLuo,


>1, Viblast first time to load the video always choose the middle quality (540p) for playback,

>Is this an existing problem?

No, this is not a problem. Viblast Player always starts with the middle quality as there is no information about the viewer's bandwitdh. You can force the initial quality by passing a configuration parameter to the player setup: initial-abr-index. In your case if you want to start the playback with the highest quality, you have to set '2' as a value of initial-abr-index. If you want to start with the lowest quality, you have to set it to '0'. More about the player parameters you can read here. There is another important ABR parameter: abr-consider-demensions. When it is set to "true"/the default/, Viblast Player will choose the best quality for the current player dimensions.

>2, when I switch from low to high quality for quality selection, the video will be backwards.

>I think when Viblast switch quality playback, there is no correct match to the currently playing frame, >and select the current frame after the video to play.

>Is this an existing problem?

Can you confirm that your playlists are ABR aligned and produced following the rules?

Can you share more about your streaming server setup or provide a test stream?

Viblast Player should switch smoothly between the qualities if the playlists are correct.


Hi,


We checked your playlist and it is definitely not an ABR compliant.

The quality "1925872" contains chunks with 10 seconds duration, while qualities "1164848" and "482784" are with 2 seconds segment duration.


Thank you for your response.


As you mentioned, segment duration is not the same.
I think that both in the case of Live or VOD, Segment duration may be different.
In this case, if Viblast can smoothly switch the quality, it would be perfect.
I hope to get your improvement.


Thank you very much!

Hi,

This is difficult/close to impossible/ to align streams with different qualities and segment length. We do not have plans to implement such an improvement as this is not a standard.


Best regards,


Hi


Thank you for your answer.

Can I get Viblist callback notification when Viblast switch the quality automatically?

I want to show the loading icon at this time and control Viblast to play the latest video instead of rewind.


Best regards

Hi 

>>Viblast Player always starts with the middle quality as there is no information about the viewer's bandwitdh.


Viblast Player start with middle quality (540p) video, and then according to the network environment to switch the most suitable bitrate for playback.

But when Viblast switch to High quality (720p), it will take a long time. Is there any problem?

Here is Viblast request data sequence, between No4 and No5 Viblast spent about 5 seconds to request the High quality segement file, and during this period player shown Loading.

 


1, playlist.m3u8
2, chunklist_b996000.m3u8
3, media-xxx_b996000_562.ts
4, chunklist_b2179072.m3u8
5, media-xxx_b2179072_224.ts
6, media-xxx_b2179072_225.ts
7, media-xxx_b2179072_226.ts

 Best regards

Hi,

Do you have a public available test stream?

You don't have to see the loading icon, as the transition between the qualities should be smooth. 

Best regards,

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