Use "JPEG 2000" as long name for j2k.

libavcodec/j2kdec.c

@@ -1062,6 +1062,7 @@ AVCodec ff_jpeg2000_decoder = {
     decode_end,
     decode_frame,
     .capabilities = CODEC_CAP_EXPERIMENTAL,
+    .long_name = NULL_IF_CONFIG_SMALL("JPEG 2000"),
     .pix_fmts =
         (enum PixelFormat[]) {PIX_FMT_GRAY8, PIX_FMT_RGB24, -1}
 };

libavcodec/j2kenc.c

@@ -1043,6 +1043,7 @@ AVCodec ff_jpeg2000_encoder = {
     encode_frame,
     j2kenc_destroy,
     .capabilities= CODEC_CAP_EXPERIMENTAL,
+    .long_name = NULL_IF_CONFIG_SMALL("JPEG 2000"),
     .pix_fmts =
         (enum PixelFormat[]) {PIX_FMT_RGB24, PIX_FMT_YUV444P, PIX_FMT_GRAY8,
 /*                              PIX_FMT_YUV420P,