Control keyframe time distance in omxh264enc

[Rik Sagar]

Hi Sebastian/Augusto,

On the TI and Qualcomm chips that we worked with, at Palm, you could set
the keyframe generation to be either periodic or on demand.

For the video recorder app we had a 1/2 second distance between iframes -
to facilitate easy editing of the video (chop at keyframes).

I would expect it to be a supported on other hardware, it seems a fairly
reasonable thing to have.

It's been a year or two since I needed to look at this, so I just skimmed
through the OpenMAX spec, and I see a couple of things that look familiar:
   - OMX_VIDEO_CONFIG_AVCINTRAPERIOD
   - OMX_VIDEO_PARAM_H263TYPE

Both have a field called *nPFrames* which controls the distance between
iFrames.

Regards,
Rik.




On Tue, Aug 6, 2013 at 11:44 PM, Sebastian Dröge
<slomo at circular-chaos.org>wrote:

> On Di, 2013-08-06 at 14:06 +0200, Augusto Destrero wrote:
> > Hi there,
> > in my application using gstreamer-omx on the Raspberry PI I would like
> to have
> > a short time distance between keyframes in a h264 stream.
> >
> > Is there a way to control the maximum time distance between keyframes in
> > omxh264enc?
>
> There isn't and IIRC there is also no API to do this in OpenMAX or on
> the RPi other than forcing a keyframe.
>
> Currently the encoder has already support for forcing keyframes (with
> the force-keyunit event). I don't know if RPi implements this, but if it
> does you could add a property to gst-omx to use this for forcing a
> keyframe at least every N seconds.
>
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>
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