avformat/img2_alias_pix: Add AVClass and image2 AVOptions

This fixes the default timebase and allows overriding the framerate
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/img2_alias_pix.c

@@ -54,6 +54,13 @@ static int alias_pix_read_probe(AVProbeData *p)
     return AVPROBE_SCORE_EXTENSION + 1;
 }
 
+static const AVClass image2_alias_pix_class = {
+    .class_name = "alias_pix demuxer",
+    .item_name  = av_default_item_name,
+    .option     = ff_img_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 AVInputFormat ff_image2_alias_pix_demuxer = {
     .name           = "alias_pix",
     .long_name      = NULL_IF_CONFIG_SMALL("Alias/Wavefront PIX image"),
@@ -62,4 +69,5 @@ AVInputFormat ff_image2_alias_pix_demuxer = {
     .read_header    = ff_img_read_header,
     .read_packet    = ff_img_read_packet,
     .raw_codec_id   = AV_CODEC_ID_ALIAS_PIX,
+    .priv_class     = &image2_alias_pix_class,
 };