Increasing latency over wifi

[pili-engineering]

Increasing latency over wifi

[jpxiong]

PLDroidCameraStreaming is only to catch the video/audio data, encode them and send them. If the network is not good, PLDroidCameraStreaming will drop the old frame simpley. SO it won't happen latency on the PLDroidCameraStreaming side.

PLDroidPlayer will have no buffering in ffmpeg layer if you set the fflags to nobuffer, as the following:

options.setString(AVOptions.KEY_FFLAGS, AVOptions.VALUE_FFLAGS_NOBUFFER); // "nobuffer"

You can check the -fflags nobuffer from here.

[jpxiong]

BTW, We are going to remove the ffmpeg dependency from PLDroidCameraStreaming, and we just use the ffmpeg to packet and delivery the encoded datas.

[alcastelo]

Great news from the streamer side!!
In the PLDroidPlayer layer, i made a little dirty hack, that seems to reduce greatly the latency.
Since our toruble, cames from network traffic, I removed the nobuffer fflag, to make sure the player is reading from network as fast as posible into the buffers, and make the player discard every frame except the last one. I change latency for little dropouts.
Its a very dirty solution, but seems to avoid almost all the latency on the player side 😄
Thanks again.

[jpxiong]

NO. If you remove the nobuffer flag, you can't play the newest frame, but the frame which buffering some time. So the latency will happen.

[alcastelo]

Im discarding every frame in buffer except the last one (inside the ffplay.c).
Ill make a copule of test more, but the latency realy improves drastically, at least in my case

[jpxiong]

Oh, I see. You have customized the ffplay.c. Nice.

[alcastelo]

if you want to give it a try, i think i could try to make a fork of your project, so you can test the latency on your network.

[jpxiong]

That's great!

But i guess there is a problem: if the network jitter happens, you can't watch a smooth video(or blurred screen), as you discarding every frame except the last one. I think the user experience is not good.

[alcastelo]

Really, user experience degrades as frames are discarded, but in this case, we really need the lowest latency posible, and sacrifice a little video quality seems feasible.
Anyway, I appreciate greatly all your work, and i will try to make the fork as soon as i can
Thanks again.

[jpxiong]

You are welcome. Any issue can discuss here.

I will try your strategy later. Please let me know if it's ready. Thanks.

[gouravd]

Could you elaborate a bit on this? What is the current dependency of FFmpeg
as of v1.3.0.

Once you remove the dependency on FFmpeg, how would you allow to stream to
rtmp?
On Aug 24, 2015 8:15 PM, "jpxiong" [email protected] wrote:

BTW, We are going to remove the ffmpeg dependency from
PLDroidCameraStreaming, and we just use the ffmpeg to packet and delivery
the encoded datas.

—
Reply to this email directly or view it on GitHub
#18 (comment)
.

[jpxiong]

FFmpeg is for packeting and delivering encoded data. We will packet encoded data to flv by ourselves and delivery by librtmp.

[alcastelo]

Hi there.
Sorry for the delay, i was a little busy yesterday.

If you want to make some test, there is a repository for the library here https://github.com/alcastelo/ijkplayer. Only one file has changed, maybe it will be faster for you to copy it and recompile.
Remenber to remove the -fflags nobuffer.
I now the hack is veryyyy ugly, but this is only a proof of concept.
Sorry about the inconveniences, and thanks for your time and work

[jpxiong]

Thanks.