[x264-devel] Encoding frames with libavcodec

[Jason Garrett-Glaser]

On Thu, Dec 13, 2012 at 8:19 AM, Dolevo Jay <cmst at live.com> wrote:
> Hi Jason,
>
> As you suggested, I am currently using x264_param_default_preset(&param,
> "ultrafast", "zerolatency");
> It is working perfect. The delay is not so much and to be honest ignorable.
> However, the bandwidth goes above than 8 Mbps when watching some ultra HD
> videos with high details. This is unwanted and I need to keep it lower than
> 8 Mbps. For this purpose, I set the encoder to superfast instead of
> ultrafast and this gives the bitrate results that I want. As a drawback, the
> delay has increased, which is understandable and no problem at all in my
> application. However, the frame rate has also dropped, which is not good.
> The frame rate further drops if I choose down to veryfast or faster. Could
> you please guide me to have parameter settings for the following
> requirements:
> 1. Bitrate can be higher than that of what I am getting in superfast setting
> but should definitely be lower than ultrafast setting,

Have you tried setting your VBV settings accordingly?  The bitrate
won't go above what you tell x264 the bitrate should be.

> 2. Frame rate should be minimum 18 fps in any case. I mean this is not a
> sharp limit but at least I should have the same frame rate result that I am
> having in ultrafast mode.

I'm not psychic, so I have no idea how fast a particular preset will
go on your particular computer.

> 3. Quality should be about the same in either settings.
> 4. Delay is not a problem. Can be even 2-3 seconds.

Then you don't need zerolatency!  Try not using it.

Jason