lavc: add new API for iterating codecs and codec parsers

Based on an unfinished patch by atomnuker.

Makefile

@@ -142,7 +142,8 @@ distclean:: clean
 	$(RM) .version avversion.h config.asm config.h mapfile  \
 		ffbuild/.config ffbuild/config.* libavutil/avconfig.h \
 		version.h libavutil/ffversion.h libavcodec/codec_names.h \
-		libavcodec/bsf_list.c libavformat/protocol_list.c
+		libavcodec/bsf_list.c libavformat/protocol_list.c \
+		libavcodec/codec_list.c libavcodec/parser_list.c
 ifeq ($(SRC_LINK),src)
 	$(RM) src
 endif

configure

@@ -3525,9 +3525,6 @@ find_things(){
     sed -n "s/^[^#]*$pattern.*([^,]*, *\([^,]*\)\(,.*\)*).*/\1_$thing/p" "$file"
 }
 
-ENCODER_LIST=$(find_things  encoder  ENC      libavcodec/allcodecs.c)
-DECODER_LIST=$(find_things  decoder  DEC      libavcodec/allcodecs.c)
-PARSER_LIST=$(find_things   parser   PARSER   libavcodec/allcodecs.c)
 MUXER_LIST=$(find_things    muxer    _MUX     libavformat/allformats.c)
 DEMUXER_LIST=$(find_things  demuxer  DEMUX    libavformat/allformats.c)
 OUTDEV_LIST=$(find_things   outdev   OUTDEV   libavdevice/alldevices.c)
@@ -3541,6 +3538,13 @@ find_things_extern(){
     sed -n "s/^[^#]*extern.*$pattern *ff_\([^ ]*\)_$thing;/\1_$thing/p" "$file"
 }
 
+ENCODER_LIST=$(find_things_extern encoder AVCodec libavcodec/allcodecs.c)
+DECODER_LIST=$(find_things_extern decoder AVCodec libavcodec/allcodecs.c)
+CODEC_LIST="
+    $ENCODER_LIST
+    $DECODER_LIST
+"
+PARSER_LIST=$(find_things_extern parser AVCodecParser libavcodec/parser.c)
 BSF_LIST=$(find_things_extern bsf AVBitStreamFilter libavcodec/bitstream_filters.c)
 HWACCEL_LIST=$(find_things_extern hwaccel AVHWAccel libavcodec/hwaccels.h)
 PROTOCOL_LIST=$(find_things_extern protocol URLProtocol libavformat/protocols.c)
@@ -7029,6 +7033,8 @@ print_enabled_components(){
     cp_if_changed $TMPH $file
 }
 
+print_enabled_components libavcodec/codec_list.c AVCodec codec_list $CODEC_LIST
+print_enabled_components libavcodec/parser_list.c AVCodecParser parser_list $PARSER_LIST
 print_enabled_components libavcodec/bsf_list.c AVBitStreamFilter bitstream_filters $BSF_LIST
 print_enabled_components libavformat/protocol_list.c URLProtocol url_protocols $PROTOCOL_LIST
 

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2018-01-xx - xxxxxxx - lavc 58.9.100 - avcodec.h
+  Deprecate use of avcodec_register(), avcodec_register_all(), and
+  av_codec_next(). Add av_codec_iterate().
+
 2018-02-xx - xxxxxxx - lavf 58.8.100 - avformat.h
   Deprecate the current names of the RTSP "timeout", "stimeout", "user-agent"
   options. Introduce "listen_timeout" as replacement for the current "timeout"

libavcodec/.gitignore

@@ -2,3 +2,5 @@
 /*_tables.c
 /*_tables.h
 /bsf_list.c
+/codec_list.c
+/parser_list.c