The profile should be negotiated with downstream via caps

(In reply to Sebastian Dröge (slomo) from comment #1)
> The profile should be negotiated with downstream via caps

For what I understand cabac generate an h264 stream with "high" profile while cavlc a "baseline" profile. I don't think we can have cavlc and high profile or cabac and baseline profile. Do you mean we need to use cabac/cavlc without a property but based on downstream caps or both?

we need to mantain compatibility with openh264 version < 1.5? (no cabac there)

(In reply to Nicola from comment #2)
> (In reply to Sebastian Dröge (slomo) from comment #1)
> > The profile should be negotiated with downstream via caps
> 
> For what I understand cabac generate an h264 stream with "high" profile
> while cavlc a "baseline" profile. I don't think we can have cavlc and high
> profile or cabac and baseline profile.

AFAIK high profile allows cabac and cavlc. And high profile also includes lots of other features that are not in baseline.

> Do you mean we need to use
> cabac/cavlc without a property but based on downstream caps or both?

If downstream wants baseline profile but the property is set, we should either ignore the property or error out.

> we need to mantain compatibility with openh264 version < 1.5? (no cabac
> there)

Yes

Created attachment 314628 [details] [review]
patch v2

here are the results with this patch:

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=1 ! fakesink

will produce h264 high profile

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=0 ! fakesink

will produce h264 baseline profile as before


gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=1 ! video/x-h264,profile=baseline ! fakesink

will produce baseline profile and entropy coding is resetted to CAVLC with this log

baseline profile requested in downstream caps, entropy codec resetted to CAVLC

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=1 ! video/x-h264,profile=high ! fakesink

will produce high profile with cabac entropy coding

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=0 ! video/x-h264,profile=high ! fakesink

will produce high profile with cavlc entropy coding.

Regarding openh264 < 1.4

1) GST_OPENH264_CABAC so the property cannot be setted
2) in negotiate method, negotiation is not allowed and so the profile is setted to baseline since cavlc is the only option

Some corrections:

Regarding openh264 < 1.5

1) GST_OPENH264_CABAC is hidden so the property cannot be setted
2) in negotiate method, negotiation is not allowed and so the profile is setted to baseline since cavlc is the only option

Created attachment 314700 [details] [review]
patch v3

Minor modification, test with openh264 1.4 too, here are the results

gst-inspect-1.0 openh264enc
....
....
entropy-coding      : Entropy coding mode. CABAC mode require openh264 1.5 or better
                        flags: readable, writable
                        Enum "GstOpenh264encEntropyCodingMode" Default: 0, "CAVLC"
                           (0): CAVLC            - Context-adaptive variable-length coding

so only CAVLC is possibile

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=1 ! fakesink

0:00:00.025827574 26595      0x163ea70 ERROR           GST_PIPELINE grammar.y:454:gst_parse_element_set: could not set property "entropy-coding" in element "openh264enc0" to "1"
WARNING: erroneous pipeline: could not set property "entropy-coding" in element "openh264enc0" to "1"

and no downstream caps negotiation is possibile (as before this patch)

gst-launch-1.0 -v videotestsrc ! openh264enc entropy-coding=0 ! video/x-h264,profile=high ! fakesink

...
gstbasesrc.c(2943): gst_base_src_loop (): /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0:
streaming task paused, reason not-negotiated (-4)
...

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