Extra 15 sec delay when buffer sharing

Second client watching the same channel (tested on ATSC 3.0) is delayed 15 seconds. Show Stats/Total Cache shows 15s.

Sharing existing connection to .... gets logged immediately before the 15 secs delay.

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This should be trivial to verify ...

Are you saying it takes 15s to start playing, or it's playing with a 15s buffer so the stream is delayed compared to live?

Both, it takes 15 seconds to start and when it does the buffer has 15 secs of cache. The first TV has only 5secs of data in the buffer so the second TV is 10 secs behind. The client is waiting for something before it starts playing.

VLC just plays w/o any buffering. So it seems the problem is on the client.

Need client diagnostics after it happens


Client diagnostics uploaded from ATV

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What am I looking for? What channel number or tuner id?

Chan 123.1 tuner XXXX1D0C
Submitted diagnostics again

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Okay I see the issue in the logs. The player has to read ~10mb off the stream to find the audio/video details. It must be related to the broadcast format in your area.

Can you use curl to capture 30s of data from the stream.mpg endpoint while tuner is being shared, then email the resulting file to [email protected]

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I uploaded the file here - https://easyupload.io/5o5ak3
This problem happens in more than one location. I started having issues a while back:

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That sample should have tuned within 1.5s (1.2mb read vs 10mb+ from your previous logs). If you can capture another sample which corresponds to slow tune maybe I can find some optimizations.

I can never capture what you want using curl, VLC always plays fine.

Not relevant

Will you accept a tcpdump capture from when ATV is tuning in?

Uffff, thanks for tcpflow, it extracts the http body. I captured 5 times the process of tuning in using ATV while the channel was being played elsewhere. I stopped when ATV started playing. Only the first attempt was fast


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FYI I too notice this exact same behavior on a regular basis.

Can this issue get some love? :wink:

One of the channels is only 960x540 at less than 1Mbps and buffering takes over 60 seconds even if nobody else is watching.

@tmm1 I will send some diagnostics tomorrow if it will help you get to the bottom of it?!?!?

I just sent over 2 diagnostics from 3 diff devices.... gen1 onn android tv 4k streaming box, gen2 onn google tv 4k streaming box, and amazon fire tv.

all 6 of these diagnostics are tuning in channels 106.1 which is also being tuned from other devices on channels dvr. it takes roughly 11 seconds to tune where as if if you tune a diff atsc3 station that is not being viewed on another device takes about 3-4 seconds to tune.

Thanks we're looking into what's possible here.

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I think this is a manifestation of a common phenomena, generally caused by good intentions:

Please reduce bufferbloat :wink: