[Libav-user] Recommended settings for low latency x264 via RTP

[poste9]

set vsync to 0

2015-04-08 10:51 GMT-03:00 Info || Non-Lethal Applications <
info at non-lethal-applications.com>:

> We’re trying to send an x264 encoded RTP stream to an iOS device.
> While it works in general, we aren’t sure if we have the best settings to
> achieve our goal.
> We read on a blog from an x264 developer that it should be possible to
> achieve a latency of x264 encoded RTP streams of around 10 ms from end to
> end.
>
> We are nowhere near that in our setup.
> The lowest we can get is > 1 sec.
>
> Here are the settings we are using (c is the AVCodecContext pointer):
>
> c->bit_rate_tolerance = 0;
> c->rc_max_rate = 0;
> c->rc_buffer_size = 0;
> c->gop_size = 5;
> c->max_b_frames = 0;
> c->b_frame_strategy = 1;
> c->coder_type = 1;
> c->me_cmp = 1;
> c->me_range = 16;
> c->qmin = 10;
> c->qmax = 51;
> c->scenechange_threshold = 40;
> c->flags |= CODEC_FLAG_LOOP_FILTER;
> c->me_method = ME_HEX;
> c->me_subpel_quality = 5;
> c->i_quant_factor = 0.71;
> c->qcompress = 0.6;
> c->max_qdiff = 4;
>
> Additionally, we tried to set some libx264 private settings like so:
>
> av_opt_set(_pVideoCodecCtx->priv_data, "preset", "ultrafast", 0);
> av_opt_set(_pVideoCodecCtx->priv_data, "tune", "zerolatency", 0);
> av_opt_set(_pVideoCodecCtx->priv_data, "g", “30", 0);
>
> Does anyone have a hint what we could do to get more speed?
> Also, is there anything we can set on the decoder side to decrease
> the delay?
> We are on the defaults there.
>
> Thanks!
>
> Best regards,
>
> Flo
>
> _______________________________________________
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> Libav-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/libav-user
>
>


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