[Live-devel] Stream h264 - bitrate's effect on latency

[Mark Theunissen]

They're in close proximity - for a live sport event. So all on the same
network.

Thanks, I'll take a look into some of your suggestions!


On Mon, Apr 28, 2014 at 2:00 PM, Jeff Shanab <jshanab at jfs-tech.com> wrote:

> That is a reasonable resolution so you should not have multi-slice
> keyframes. Stick to main or baseline, High would probably be 2 pass with B
> frames.
> H264 is of course comprised of Key frames and difference frames. But the
> decoder should pump out one frame per iteration at one frame delay.
>
> Synchronizing multiple sources is an interesting issue. You will have to
> buck the tradition of ignoring the absolute time and using the timestamps
> only as a relative indicator. Instead sync the clocks on the Pi's and then
> rely on this time???. Probably pick one Pi as a time server and the other
> two use that to keep the clocks synced. Then control the two encoders
> relative to this clock so you even start the Keyframe generation in sync.
>
> Perhaps the master Pi could run live555 and create a single Transport
> stream with multiple video streams from the other Pi's. The transport
> stream is defined as a container for streams sharing the same clock base.
>
> Is this to sync multiple cameras in close proximity? or distant?
>
>
> On Mon, Apr 28, 2014 at 7:23 AM, Mark Theunissen <
> mark.theunissen at gmail.com> wrote:
>
>> > What is the resolution / profile?
>>
>> I'm at 854x480. I've tried baseline, high and main. Same result.
>>
>> I'm using UDP.
>>
>> Encoded in hardware on the Pi's Broadcom chip.
>>
>> > Whoa? did I hear you correctly? stdin? I cannot even speculate how you
>> can
>> > quantify stdin timing. (try sockets, shared memory)
>>
>> So should I try using perhaps v4l2 driver (/dev/video0) instead of piping
>> from one program to live555's stdin?
>>
>> > Make sure you create your timestamps at end of image capture/beginning
>> of
>> > encoding time. Since you are the source, the timestamps can be based all
>> > off the same clock.
>>
>> I am the source, but it's 3 different computers (raspberry pis) - not
>> sure how to sync in that case?
>>
>> Thanks for your replies and help.
>>
>> - Mark
>>
>
>
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