[FFmpeg-devel] Live streaming of VP8
Andy Bell
allbabel at gmail.com
Sat Jun 9 18:00:58 CEST 2012
On 9 Jun 2012, at 17:14, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Sat, Jun 09, 2012 at 04:51:23PM +0200, Andy Bell wrote:
>> Hi All,
>>
>> I am streaming a VP8 stream over network and using the following code to
>> encode:
>>
>> _bitRate = 500 * 1000;
>> _codecContext->bit_rate = _bitRate; // --target-bitrate=500
>> _codecContext->rc_min_rate = _codecContext->rc_max_rate =
>> _codecContext->bit_rate; // --end-usage=cbr
>>
>> _codecContext->thread_count = 4;
>> _codecContext->qmin = 4;
>> _codecContext->qmax = 56;
>> _codecContext->width = 800;
>> _codecContext->height = 600;
>> _codecContext->rc_buffer_aggressivity = 0.95; // --undershoot-pct=95
>> _codecContext->rc_buffer_size = _bitRate * 6; // --buz-sz=6000 ms
>> _codecContext->rc_initial_buffer_occupancy = _bitRate * 4; //
>> --buf-initial-sz=4000 ms
>> _codecContext->profile = 3;
>> _codecContext->time_base.num = 1;
>> _codecContext->time_base.den = 25;
>> _codecContext->gop_size = 999999; // --kf-max-dist
>>
>> This works fine but when there is a huge scene change the codec generates a
>> key frame which I am having trouble transmitting in realtime over the
>> network due to the sudden jump in bitrate.
>
> rc_buffer_size indicates a wanted max latency of 6 seconds
> if you want it to be less you can use a smaller value
>
> [...]
>
Forgive my ignorance but can you explain why that would help?
Thanks, Andy
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