[Spice-devel] [PATCH spice-gtk v2 3/5] display-gst: check GstRegistry for decoding elements

[Frediano Ziglio]

> 
> From: Victor Toso <me at victortoso.com>
> 
> With this patch, we can find all the elements in the registry that are
> video decoders which can handle the predefined GstCaps.
> 
> Main benefits are:
> - We don't rely on predefined list of GstElements. We don't need to
>   update them;
> - debugging: It does help to know what the registry has at runtime;
> 
> Signed-off-by: Victor Toso <victortoso at redhat.com>
> Signed-off-by: Victor Toso <me at victortoso.com>

Acked-by: Frediano Ziglio <fziglio at redhat.com>


> ---
>  src/channel-display-gst.c | 49
>  +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> index 7323ce7..a9c45f6 100644
> --- a/src/channel-display-gst.c
> +++ b/src/channel-display-gst.c
> @@ -535,6 +535,54 @@ VideoDecoder* create_gstreamer_decoder(int codec_type,
> display_stream *stream)
>  G_GNUC_INTERNAL
>  gboolean gstvideo_has_codec(int codec_type)
>  {
> +#if GST_CHECK_VERSION(1,9,0)
> +    GList *all_decoders, *codec_decoders;
> +    GstCaps *caps;
> +    GstElementFactoryListType type;
> +
> +    g_return_val_if_fail(gstvideo_init(), FALSE);
> +    g_return_val_if_fail(VALID_VIDEO_CODEC_TYPE(codec_type), FALSE);
> +
> +    type = GST_ELEMENT_FACTORY_TYPE_DECODER |
> GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO;
> +    all_decoders = gst_element_factory_list_get_elements(type,
> GST_RANK_NONE);
> +    if (all_decoders == NULL) {
> +        spice_warning("No video decoders from GStreamer were found");
> +        return FALSE;
> +    }
> +
> +    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);
> +    gst_caps_unref(caps);
> +
> +    if (codec_decoders == NULL) {
> +        spice_debug("From %u decoders, none can handle '%s'",
> +                    g_list_length(all_decoders),
> gst_opts[codec_type].dec_caps);
> +        gst_plugin_feature_list_free(all_decoders);
> +        return FALSE;
> +    }
> +
> +    if (spice_util_get_debug()) {
> +        GList *l;
> +        GString *msg = g_string_new(NULL);
> +        /* Print list of available decoders to make debugging easier */
> +        g_string_printf(msg, "From %3u video decoder elements, %2u can
> handle caps %12s: ",
> +                        g_list_length(all_decoders),
> g_list_length(codec_decoders),
> +                        gst_opts[codec_type].dec_caps);
> +
> +        for (l = codec_decoders; l != NULL; l = l->next) {
> +            GstPluginFeature *pfeat = GST_PLUGIN_FEATURE(l->data);
> +            g_string_append_printf(msg, "%s, ",
> gst_plugin_feature_get_name(pfeat));
> +        }
> +
> +        msg->str[msg->len - 2] = '\0';
> +        spice_debug("%s", msg->str);
> +        g_string_free(msg, TRUE);
> +    }
> +
> +    gst_plugin_feature_list_free(codec_decoders);
> +    gst_plugin_feature_list_free(all_decoders);
> +    return TRUE;
> +#else
>      gboolean has_codec = FALSE;
>  
>      VideoDecoder *decoder = create_gstreamer_decoder(codec_type, NULL);
> @@ -544,4 +592,5 @@ gboolean gstvideo_has_codec(int codec_type)
>      }
>  
>      return has_codec;
> +#endif
>  }