[FFmpeg-devel] [PATCH] restoring binary compatibility with ffmpeg 0.5

[Reinhard Tartler]

On So, Jun 06, 2010 at 17:17:16 (CEST), Reimar D?ffinger wrote:

> On Sun, Jun 06, 2010 at 05:03:40PM +0200, Reinhard Tartler wrote:
>> +void ff_av_destruct_packet_nofree(AVPacket *pkt)
>> +{
>> +    void (*fn)(AVPacket *pkt) = dlsym(avformat_handle, "av_destruct_packet_nofree");
>> +    if (!fn)
>> +        av_log(NULL, AV_LOG_FATAL, "Failed to locate symbol: av_destruct_nofree\n");
>> +    (*fn)(pkt);
>
> And adding and calling a special stub function in lavc certainly is much less hackish than
> this.

I tried this, but applications that have been compiled against ffmpeg
0.5.1 really really hard expect this symbol in avformat with this symbol.

>> +__asm__(".symver ff_av_destruct_packet_nofree,av_destruct_packet_nofree at LIBAVFORMAT_52");
>
> Though I think unless this does not really work right (which means even more problems),
> why is this not just
> void ff_av_destruct_packet_nofree(AVPacket *pkt)
> {
>     av_destruct_packet_nofree(pkt);
> }

doh, you're (as always) right, this simplifies my patch a bit. Here is
the updated, simplified patch. It works as well for me.

Index: configure
===================================================================
--- configure	(revision 23498)
+++ configure	(working copy)
@@ -1086,6 +1086,7 @@
     struct_sockaddr_in6
     struct_sockaddr_sa_len
     struct_sockaddr_storage
+    symbol_versioning
     sys_mman_h
     sys_resource_h
     sys_select_h
@@ -2733,7 +2734,7 @@
 
 echo "X{};" > $TMPV
 test_ldflags -Wl,--version-script,$TMPV &&
-    append SHFLAGS '-Wl,--version-script,\$(SUBDIR)lib\$(NAME).ver'
+    append SHFLAGS '-Wl,--version-script,\$(SUBDIR)lib\$(NAME).ver' && enable symbol_versioning
 
 if enabled small; then
     add_cflags $size_cflags
Index: libavformat/utils.c
===================================================================
--- libavformat/utils.c	(revision 23498)
+++ libavformat/utils.c	(working copy)
@@ -282,9 +282,53 @@
     return NULL;
 }
 
-/* memory handling */
+#if HAVE_SYMBOL_VERSIONING && LIBAVFORMAT_VERSION_MAJOR < 53
+/* compatibility trampolines for packet functions */
 
+void ff_av_destruct_packet_nofree(AVPacket *pkt);
+void ff_av_destruct_packet_nofree(AVPacket *pkt)
+{
+    av_destruct_packet_nofree(pkt);
+}
+__asm__(".symver ff_av_destruct_packet_nofree,av_destruct_packet_nofree at LIBAVFORMAT_52");
 
+void ff_av_destruct_packet(AVPacket *pkt);
+void ff_av_destruct_packet(AVPacket *pkt)
+{
+    av_destruct_packet(pkt);
+}
+__asm__(".symver ff_av_destruct_packet,av_destruct_packet at LIBAVFORMAT_52");
+
+int ff_av_new_packet(AVPacket *pkt, int size);
+int ff_av_new_packet(AVPacket *pkt, int size)
+{
+    return av_new_packet(pkt, size);
+}
+__asm__(".symver ff_av_new_packet,av_new_packet at LIBAVFORMAT_52");
+
+int ff_av_dup_packet(AVPacket *pkt);
+int ff_av_dup_packet(AVPacket *pkt)
+{
+    return av_dup_packet(pkt);
+}
+__asm__(".symver ff_av_dup_packet,av_dup_packet at LIBAVFORMAT_52");
+
+void ff_av_free_packet(AVPacket *pkt);
+void ff_av_free_packet(AVPacket *pkt)
+{
+    av_free_packet(pkt);
+}
+__asm__(".symver ff_av_free_packet,av_free_packet at LIBAVFORMAT_52");
+
+void ff_av_init_packet(AVPacket *pkt);
+void ff_av_init_packet(AVPacket *pkt)
+{
+    av_log(NULL, AV_LOG_WARNING, "diverting av_*_packet function calls to libavcodec. Recompile to improve performance\n");
+    av_init_packet(pkt);
+}
+__asm__(".symver ff_av_init_packet,av_init_packet at LIBAVFORMAT_52");
+#endif
+
 int av_get_packet(ByteIOContext *s, AVPacket *pkt, int size)
 {
     int ret= av_new_packet(pkt, size);


-- 
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4