* Changing encoding properties
@ 2020-11-30 19:10 Fritz Koenig
2020-12-09 16:26 ` Nicolas Dufresne
0 siblings, 1 reply; 3+ messages in thread
From: Fritz Koenig @ 2020-11-30 19:10 UTC (permalink / raw)
To: linux-media
When can bitrate, etc., be changed by VIDIOC_TRY_EXT_CTRLS? Any time
during encode? Only before VIDIOC_STREAMON?
My understanding is that VIDIOC_STREAMON should start actually
processing frames, everything before then is configuration. If
something needs to be adjusted then VIDIOC_STREAMOFF should be called,
changes made, and then VIDIOC_STREAMON again. Is this correct?
I didn't see anything in the documentation about this.
Thanks.
-Fritz
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Changing encoding properties
2020-11-30 19:10 Changing encoding properties Fritz Koenig
@ 2020-12-09 16:26 ` Nicolas Dufresne
2020-12-12 1:25 ` Fritz Koenig
0 siblings, 1 reply; 3+ messages in thread
From: Nicolas Dufresne @ 2020-12-09 16:26 UTC (permalink / raw)
To: Fritz Koenig, linux-media
Le lundi 30 novembre 2020 à 11:10 -0800, Fritz Koenig a écrit :
> When can bitrate, etc., be changed by VIDIOC_TRY_EXT_CTRLS? Any time
> during encode? Only before VIDIOC_STREAMON?
>
> My understanding is that VIDIOC_STREAMON should start actually
> processing frames, everything before then is configuration. If
> something needs to be adjusted then VIDIOC_STREAMOFF should be called,
> changes made, and then VIDIOC_STREAMON again. Is this correct?
Bitrate is paticular is expected to be changeable at runtime (in STREAMON
state). But a firmware may not support it, hence a driver is allowed to return
EBUSY (iirc).
Changing the bitrate without producing a new keyframe (whath cycling
STREAMOFF/ON would cause) is a highly common use case while encoding for live
streaming.
This of course should be documented.
>
> I didn't see anything in the documentation about this.
>
> Thanks.
>
> -Fritz
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Changing encoding properties
2020-12-09 16:26 ` Nicolas Dufresne
@ 2020-12-12 1:25 ` Fritz Koenig
0 siblings, 0 replies; 3+ messages in thread
From: Fritz Koenig @ 2020-12-12 1:25 UTC (permalink / raw)
To: Nicolas Dufresne; +Cc: Linux Media Mailing List
On Wed, Dec 9, 2020 at 8:26 AM Nicolas Dufresne <nicolas@ndufresne.ca> wrote:
>
> Le lundi 30 novembre 2020 à 11:10 -0800, Fritz Koenig a écrit :
> > When can bitrate, etc., be changed by VIDIOC_TRY_EXT_CTRLS? Any time
> > during encode? Only before VIDIOC_STREAMON?
> >
> > My understanding is that VIDIOC_STREAMON should start actually
> > processing frames, everything before then is configuration. If
> > something needs to be adjusted then VIDIOC_STREAMOFF should be called,
> > changes made, and then VIDIOC_STREAMON again. Is this correct?
>
> Bitrate is paticular is expected to be changeable at runtime (in STREAMON
> state). But a firmware may not support it, hence a driver is allowed to return
> EBUSY (iirc).
>
> Changing the bitrate without producing a new keyframe (whath cycling
> STREAMOFF/ON would cause) is a highly common use case while encoding for live
> streaming.
>
Thanks. That makes sense.
> This of course should be documented.
>
> >
> > I didn't see anything in the documentation about this.
> >
> > Thanks.
> >
> > -Fritz
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-12 1:27 UTC | newest]
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2020-11-30 19:10 Changing encoding properties Fritz Koenig
2020-12-09 16:26 ` Nicolas Dufresne
2020-12-12 1:25 ` Fritz Koenig
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