[FFmpeg-devel] [PATCH] examples: set GOP size to 10 seconds

[Steven Liu]

Alfred E. Heggestad <alfred.heggestad at gmail.com> 于2019年10月29日周二 下午6:08写道：
>
> On 29/10/2019 10:34, Steven Liu wrote:
> >
> >
> >> 在 2019年10月29日，17:25，Alfred E. Heggestad <alfred.heggestad at gmail.com> 写道：
> >>
> >> using a gop_size of 10 in the example code is very misleading.
> >> in practice this means around 2 keyframes per second.
> >>
> >> a normal video encoder should not send keyframes so frequent,
> >> a better interval is 10 seconds.
> >
> > 10 seconds is too long. i think 10 frames maybe ok for a sample.
> > but usually set to 2s one GOP here, for publish stream to rtmp server.
> > This is just a sample, so i think 10 second is too long.
>
> Hi Steven,
>
> I think we should make it clear in the code that the GOP size
> depends on the framerate. Keep in mind that many people just copy
> the example code to use in their applications, and does not
> necessarily try to understand all the small details.
>
>
> I am sure we can agree on a nice value for the keyframe interval,
> but my point is that the value should be in seconds and not frames.

Yes i get your point, but the comment of the gop_size is:

    /**
     * the number of pictures in a group of pictures, or 0 for intra_only
     * - encoding: Set by user.
     * - decoding: unused
     */
    int gop_size;
Maybe user should read the document or the API's comments before they
use it, not only copy & paste.

>
> For example 5 seconds:
>
>
>    c->gop_size = 5 * FPS;
>
>
>
>
> /alfred
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