smoothstreaming: Export the mp4 codec tags

This fixes stream copy from a format that already has incompatible
codec tags set. The chained ismv muxer exports this same codec tag
list, so set it on this one as well, to allow the caller (and
lavf common code) to set them correctly.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/Makefile

@@ -292,7 +292,7 @@ OBJS-$(CONFIG_SIFF_DEMUXER)              += siff.o
 OBJS-$(CONFIG_SMACKER_DEMUXER)           += smacker.o
 OBJS-$(CONFIG_SMJPEG_DEMUXER)            += smjpegdec.o smjpeg.o
 OBJS-$(CONFIG_SMJPEG_MUXER)              += smjpegenc.o smjpeg.o
-OBJS-$(CONFIG_SMOOTHSTREAMING_MUXER)     += smoothstreamingenc.o
+OBJS-$(CONFIG_SMOOTHSTREAMING_MUXER)     += smoothstreamingenc.o isom.o
 OBJS-$(CONFIG_SOL_DEMUXER)               += sol.o pcm.o
 OBJS-$(CONFIG_SOX_DEMUXER)               += soxdec.o pcm.o
 OBJS-$(CONFIG_SOX_MUXER)                 += soxenc.o

libavformat/smoothstreamingenc.c

@@ -30,6 +30,7 @@
 #include "os_support.h"
 #include "avc.h"
 #include "url.h"
+#include "isom.h"
 
 #include "libavutil/opt.h"
 #include "libavutil/avstring.h"
@@ -617,5 +618,6 @@ AVOutputFormat ff_smoothstreaming_muxer = {
     .write_header   = ism_write_header,
     .write_packet   = ism_write_packet,
     .write_trailer  = ism_write_trailer,
+    .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
     .priv_class     = &ism_class,
 };