transcode: disable hardware decoding by default

It can still be enabled manually in the preferences as in previous
versions. Only it will not be used with the default ("auto") setting.

modules/codec/avcodec/avcodec.c

@@ -135,7 +135,7 @@ vlc_module_begin ()
     add_obsolete_string( "ffmpeg-codec" ) /* removed since 2.1.0 */
     add_string( "avcodec-codec", NULL, CODEC_TEXT, CODEC_LONGTEXT, true )
     add_obsolete_bool( "ffmpeg-hw" ) /* removed since 2.1.0 */
-    add_module( "avcodec-hw", "hw decoder", NULL, HW_TEXT, HW_LONGTEXT, false )
+    add_module( "avcodec-hw", "hw decoder", "any", HW_TEXT, HW_LONGTEXT, false )
 #if defined(FF_THREAD_FRAME)
     add_obsolete_integer( "ffmpeg-threads" ) /* removed since 2.1.0 */
     add_integer( "avcodec-threads", 0, THREADS_TEXT, THREADS_LONGTEXT, true );

modules/stream_out/transcode/transcode.c

@@ -383,6 +383,12 @@ static int Open( vlc_object_t *p_this )
                  p_sys->f_scale, p_sys->i_vbitrate / 1000 );
     }
 
+    /* Disable hardware decoding by default (unlike normal playback) */
+    psz_string = var_CreateGetString( p_stream, "avcodec-hw" );
+    if( !strcasecmp( "any", psz_string ) )
+        var_SetString( p_stream, "avcodec-hw", "none" );
+    free( psz_string );
+
     /* Subpictures transcoding parameters */
     p_sys->p_spu = NULL;
     p_sys->p_spu_blend = NULL;