Hi,
On Wed, Jul 19, 2017 at 11:34:14AM +0200, Victor Toso wrote:
> Hi,
>
> On Thu, Jul 13, 2017 at 02:33:48PM +0200, Victor Toso wrote:
> > From: Victor Toso <me@xxxxxxxxxxxxxx>
> >
> > This patch fixes the avdec_h264 element not being present on
> > gstvideo_has_codec() which get all decoder elements from GstRegistry
> > and filter them on our GstCaps in order to get the ones for given
> > codec.
> >
> > The issue is around the filtering. The current GstCaps for h264 is not
> > consider a subset of avdec_h264's capabilites and that will fiter this
> > element out of the list.
> >
> > The proposed solution for that is to set `subsetonly` parameter from
> > gst_element_factory_list_filter() to false.
> >
> > While at it, the cap "stream-format=byte-stream" is less useful now
> > because it isn't needed to play the stream - see 6fe88871240c53b8
> >
> > In my system, our debug shows:
> > .. gstvideo_debug_available_decoders: From 228 video decoder elements,
> > - 4 can handle caps image/jpeg: jpegdec, nvdec, avdec_mjpeg, vaapijpegdec
> > - 3 can handle caps video/x-vp8: vaapidecodebin, vp8dec, avdec_vp8
> > - 4 can handle caps video/x-h264: vaapidecodebin, avdec_h264, nvdec, vaapih264dec
> > - 3 can handle caps video/x-vp9: vaapidecodebin, vp9dec, avdec_vp9
> >
> > Signed-off-by: Victor Toso <victortoso@xxxxxxxxxx>
>
> I consider this one a blocker to the release as a client that had only
> the avdec_h264 decoder for h264, would be able to decode h264 streams
> but without this patch it can't as we will not find any available
> decoder due wrong filtering which will disable the capability for h264
> decoding.
>
> Any comments?
The related discussion below...
(2017-07-13 at #gstreamer - freenode)
toso Hi, I'm wondering if I'm getting the documentation wrong about
the meaning of gst_caps_is_subset()... isn't it "video/x-h264,
stream-format=(string)byte-stream" a subset of "video/x-h264,
alignment=(string)au, stream-format=(string){ avc, byte-stream }" ?
__tim toso, no, because it's missing the alignment field
__tim which means alignment could be anything
__tim which means it might not be au
toso that's a bit confusing, no?
__tim it's not a strict subset :)
toso I really thought it would be a subset in this case.. meaning, we
don't care about the aligment on _is_subset
__tim you can do can_intersect() if you don't care
slomo it's an actual subset if you define the abscence of a field as
"the field can have every possible value"
toso __tim: problem is that it isn't a subset on calling
gst_element_factory_list_filter()
toso slomo: yeah, that was my assumption on the meaning of subset
toso so, just to confirm, this is the expected behavior and not a
bug, right? :)
slomo yes
__tim slomo, foo, bar={1,2} is not a subset of foo, bar=1 is it?
slomo but if something does not work as expect for you, that might be
a bug :)
slomo __tim: correct
slomo __tim: but foo, bar=1 is a subset of foo, bar={1,2}
__tim yes
slomo __tim: and foo, bar=1 is a subset of foo
slomo __tim: and foo is not a subset of foo, bar=1
__tim yes. yes.
__tim andn the case we're talking about is basically "foo" + "foo,
bar=1"
slomo yes, the first is a superset of the second there
slomo toso: if something does not work for you that might also be a
bug of course ;)
__tim ok, so not a subset.
__tim then we're on the same page I think :)
toso slomo: right, my point was that I would like to list the h264
decoders that are available and I was using `video/x-h264,
stream-format=byte-stream` as input for
gst_element_factory_list_filter() .. and avdec_h264 is the one
not showing because it needs the aligment
toso but as I got it wrong, I'll rethink on how to fix it
slomo toso: pass FALSE as the last argument
slomo and you can just use 'video/x-h264'
slomo and with gst_element_factory_list_get_elements() you can make
sure to get only a list of video decoders to begin with
toso just gst_element_factory_list_get_elements() gives me like 220
elements
toso using _type_decoder | _type_media_video | _type_media_image
slomo is that a problem?
toso trying to reduce that to actual decoding elements
slomo they should be all actual video decoders
slomo and with gst_element_factory_list_filter(list, 'video/x-h264',
GST_PAD_SINK, FALSE) you can then filter out all non-h264 ones
dv_ is it generally ok if an audio decoder messes with the
PTS/durations?
toso right, let me try that then
toso slomo, __tim many thanks :)
>
> > ---
> > src/channel-display-gst.c | 2 +-
> > src/channel-display-priv.h | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> > index 20d236a..1bd7df1 100644
> > --- a/src/channel-display-gst.c
> > +++ b/src/channel-display-gst.c
> > @@ -647,7 +647,7 @@ gboolean gstvideo_has_codec(int codec_type)
> > }
> >
> > caps = gst_caps_from_string(gst_opts[codec_type].dec_caps);
> > - codec_decoders = gst_element_factory_list_filter(all_decoders, caps, GST_PAD_SINK, TRUE);
> > + codec_decoders = gst_element_factory_list_filter(all_decoders, caps, GST_PAD_SINK, FALSE);
> > gst_caps_unref(caps);
> >
> > if (codec_decoders == NULL) {
> > diff --git a/src/channel-display-priv.h b/src/channel-display-priv.h
> > index 04cb4d1..9bfd4ac 100644
> > --- a/src/channel-display-priv.h
> > +++ b/src/channel-display-priv.h
> > @@ -181,7 +181,7 @@ static const struct {
> > * (hardcoded in spice-server), let's add it here to avoid the warning.
> > */
> > { SPICE_DISPLAY_CAP_CODEC_H264, "h264",
> > - "h264parse ! avdec_h264", "video/x-h264,stream-format=byte-stream" },
> > + "h264parse ! avdec_h264", "video/x-h264" },
> >
> > /* SPICE_VIDEO_CODEC_TYPE_VP9 */
> > { SPICE_DISPLAY_CAP_CODEC_VP9, "vp9",
> > --
> > 2.13.0
> >
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