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

libavcodec/avcodec.h

@@ -3978,12 +3978,26 @@ typedef struct AVCodecParameters {
     int seek_preroll;
 } AVCodecParameters;
 
+/**
+ * Iterate over all registered codecs.
+ *
+ * @param opaque a pointer where libavcodec will store the iteration state. Must
+ *               point to NULL to start the iteration.
+ *
+ * @return the next registered codec or NULL when the iteration is
+ *         finished
+ */
+const AVCodec *av_codec_iterate(void **opaque);
+
+#if FF_API_NEXT
 /**
  * If c is NULL, returns the first registered codec,
  * if c is non-NULL, returns the next registered codec after c,
  * or NULL if c is the last one.
  */
+attribute_deprecated
 AVCodec *av_codec_next(const AVCodec *c);
+#endif
 
 /**
  * Return the LIBAVCODEC_VERSION_INT constant.
@@ -4000,6 +4014,7 @@ const char *avcodec_configuration(void);
  */
 const char *avcodec_license(void);
 
+#if FF_API_NEXT
 /**
  * Register the codec codec and initialize libavcodec.
  *
@@ -4008,6 +4023,7 @@ const char *avcodec_license(void);
  *
  * @see avcodec_register_all()
  */
+attribute_deprecated
 void avcodec_register(AVCodec *codec);
 
 /**
@@ -4020,7 +4036,9 @@ void avcodec_register(AVCodec *codec);
  * @see av_register_codec_parser
  * @see av_register_bitstream_filter
  */
+attribute_deprecated
 void avcodec_register_all(void);
+#endif
 
 /**
  * Allocate an AVCodecContext and set its fields to default values. The
@@ -5120,8 +5138,21 @@ typedef struct AVCodecParser {
     struct AVCodecParser *next;
 } AVCodecParser;
 
+/**
+ * Iterate over all registered codec parsers.
+ *
+ * @param opaque a pointer where libavcodec will store the iteration state. Must
+ *               point to NULL to start the iteration.
+ *
+ * @return the next registered codec parser or NULL when the iteration is
+ *         finished
+ */
+const AVCodecParser *av_parser_iterate(void **opaque);
+
+attribute_deprecated
 AVCodecParser *av_parser_next(const AVCodecParser *c);
 
+attribute_deprecated
 void av_register_codec_parser(AVCodecParser *parser);
 AVCodecParserContext *av_parser_init(int codec_id);
 

libavcodec/parser.c

@@ -32,36 +32,100 @@
 #include "internal.h"
 #include "parser.h"
 
-static AVCodecParser *av_first_parser = NULL;
+/* Parsers */
+extern AVCodecParser ff_aac_parser;
+extern AVCodecParser ff_aac_latm_parser;
+extern AVCodecParser ff_ac3_parser;
+extern AVCodecParser ff_adx_parser;
+extern AVCodecParser ff_bmp_parser;
+extern AVCodecParser ff_cavsvideo_parser;
+extern AVCodecParser ff_cook_parser;
+extern AVCodecParser ff_dca_parser;
+extern AVCodecParser ff_dirac_parser;
+extern AVCodecParser ff_dnxhd_parser;
+extern AVCodecParser ff_dpx_parser;
+extern AVCodecParser ff_dvaudio_parser;
+extern AVCodecParser ff_dvbsub_parser;
+extern AVCodecParser ff_dvdsub_parser;
+extern AVCodecParser ff_dvd_nav_parser;
+extern AVCodecParser ff_flac_parser;
+extern AVCodecParser ff_g729_parser;
+extern AVCodecParser ff_gsm_parser;
+extern AVCodecParser ff_h261_parser;
+extern AVCodecParser ff_h263_parser;
+extern AVCodecParser ff_h264_parser;
+extern AVCodecParser ff_hevc_parser;
+extern AVCodecParser ff_mjpeg_parser;
+extern AVCodecParser ff_mlp_parser;
+extern AVCodecParser ff_mpeg4video_parser;
+extern AVCodecParser ff_mpegaudio_parser;
+extern AVCodecParser ff_mpegvideo_parser;
+extern AVCodecParser ff_opus_parser;
+extern AVCodecParser ff_png_parser;
+extern AVCodecParser ff_pnm_parser;
+extern AVCodecParser ff_rv30_parser;
+extern AVCodecParser ff_rv40_parser;
+extern AVCodecParser ff_sipr_parser;
+extern AVCodecParser ff_tak_parser;
+extern AVCodecParser ff_vc1_parser;
+extern AVCodecParser ff_vorbis_parser;
+extern AVCodecParser ff_vp3_parser;
+extern AVCodecParser ff_vp8_parser;
+extern AVCodecParser ff_vp9_parser;
+extern AVCodecParser ff_xma_parser;
+
+#include "libavcodec/parser_list.c"
+
+static AVOnce av_parser_next_init = AV_ONCE_INIT;
+
+static void av_parser_init_next(void)
+{
+    AVCodecParser *prev = NULL, *p;
+    int i = 0;
+    while ((p = (AVCodecParser*)parser_list[i++])) {
+        if (prev)
+            prev->next = p;
+        prev = p;
+    }
+}
 
 AVCodecParser *av_parser_next(const AVCodecParser *p)
 {
+    ff_thread_once(&av_parser_next_init, av_parser_init_next);
+
     if (p)
         return p->next;
     else
-        return av_first_parser;
+        return (AVCodecParser*)parser_list[0];
 }
 
-static AVMutex parser_register_mutex = AV_MUTEX_INITIALIZER;
+const AVCodecParser *av_parser_iterate(void **opaque)
+{
+    uintptr_t i = (uintptr_t)*opaque;
+    const AVCodecParser *p = parser_list[i];
+
+    if (p)
+        *opaque = (void*)(i + 1);
+
+    return p;
+}
 
 void av_register_codec_parser(AVCodecParser *parser)
 {
-    ff_mutex_lock(&parser_register_mutex);
-    parser->next = av_first_parser;
-    av_first_parser = parser;
-    ff_mutex_unlock(&parser_register_mutex);
+    ff_thread_once(&av_parser_next_init, av_parser_init_next);
 }
 
 AVCodecParserContext *av_parser_init(int codec_id)
 {
     AVCodecParserContext *s = NULL;
-    AVCodecParser *parser;
+    const AVCodecParser *parser;
+    void *i = 0;
     int ret;
 
     if (codec_id == AV_CODEC_ID_NONE)
         return NULL;
 
-    for (parser = av_first_parser; parser; parser = parser->next) {
+    while ((parser = av_parser_iterate(&i))) {
         if (parser->codec_ids[0] == codec_id ||
             parser->codec_ids[1] == codec_id ||
             parser->codec_ids[2] == codec_id ||
@@ -75,7 +139,7 @@ found:
     s = av_mallocz(sizeof(AVCodecParserContext));
     if (!s)
         goto err_out;
-    s->parser = parser;
+    s->parser = (AVCodecParser*)parser;
     s->priv_data = av_mallocz(parser->priv_data_size);
     if (!s->priv_data)
         goto err_out;

libavcodec/utils.c

@@ -46,7 +46,6 @@
 #include "decode.h"
 #include "hwaccel.h"
 #include "libavutil/opt.h"
-#include "me_cmp.h"
 #include "mpegvideo.h"
 #include "thread.h"
 #include "frame_thread_encoder.h"
@@ -92,18 +91,6 @@ void av_fast_padded_mallocz(void *ptr, unsigned int *size, size_t min_size)
         memset(*p, 0, min_size + AV_INPUT_BUFFER_PADDING_SIZE);
 }
 
-/* encoder management */
-static AVCodec *first_avcodec = NULL;
-static AVCodec **last_avcodec = &first_avcodec;
-
-AVCodec *av_codec_next(const AVCodec *c)
-{
-    if (c)
-        return c->next;
-    else
-        return first_avcodec;
-}
-
 int av_codec_is_encoder(const AVCodec *codec)
 {
     return codec && (codec->encode_sub || codec->encode2 ||codec->send_frame);
@@ -114,27 +101,6 @@ int av_codec_is_decoder(const AVCodec *codec)
     return codec && (codec->decode || codec->receive_frame);
 }
 
-static AVMutex codec_register_mutex = AV_MUTEX_INITIALIZER;
-
-av_cold void avcodec_register(AVCodec *codec)
-{
-    AVCodec **p;
-
-    ff_mutex_lock(&codec_register_mutex);
-    p = last_avcodec;
-
-    while (*p)
-        p = &(*p)->next;
-    *p          = codec;
-    codec->next = NULL;
-    last_avcodec = &codec->next;
-
-    ff_mutex_unlock(&codec_register_mutex);
-
-    if (codec->init_static_data)
-        codec->init_static_data(codec);
-}
-
 int ff_set_dimensions(AVCodecContext *s, int width, int height)
 {
     int ret = av_image_check_size2(width, height, s->max_pixels, AV_PIX_FMT_NONE, 0, s);
@@ -1155,71 +1121,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
     return 0;
 }
 
-static enum AVCodecID remap_deprecated_codec_id(enum AVCodecID id)
-{
-    switch(id){
-        //This is for future deprecatec codec ids, its empty since
-        //last major bump but will fill up again over time, please don't remove it
-        default                                         : return id;
-    }
-}
-
-static AVCodec *find_encdec(enum AVCodecID id, int encoder)
-{
-    AVCodec *p, *experimental = NULL;
-    p = first_avcodec;
-    id= remap_deprecated_codec_id(id);
-    while (p) {
-        if ((encoder ? av_codec_is_encoder(p) : av_codec_is_decoder(p)) &&
-            p->id == id) {
-            if (p->capabilities & AV_CODEC_CAP_EXPERIMENTAL && !experimental) {
-                experimental = p;
-            } else
-                return p;
-        }
-        p = p->next;
-    }
-    return experimental;
-}
-
-AVCodec *avcodec_find_encoder(enum AVCodecID id)
-{
-    return find_encdec(id, 1);
-}
-
-AVCodec *avcodec_find_encoder_by_name(const char *name)
-{
-    AVCodec *p;
-    if (!name)
-        return NULL;
-    p = first_avcodec;
-    while (p) {
-        if (av_codec_is_encoder(p) && strcmp(name, p->name) == 0)
-            return p;
-        p = p->next;
-    }
-    return NULL;
-}
-
-AVCodec *avcodec_find_decoder(enum AVCodecID id)
-{
-    return find_encdec(id, 0);
-}
-
-AVCodec *avcodec_find_decoder_by_name(const char *name)
-{
-    AVCodec *p;
-    if (!name)
-        return NULL;
-    p = first_avcodec;
-    while (p) {
-        if (av_codec_is_decoder(p) && strcmp(name, p->name) == 0)
-            return p;
-        p = p->next;
-    }
-    return NULL;
-}
-
 const char *avcodec_get_name(enum AVCodecID id)
 {
     const AVCodecDescriptor *cd;

libavcodec/version.h

@@ -129,6 +129,9 @@
 #ifndef FF_API_LOCKMGR
 #define FF_API_LOCKMGR (LIBAVCODEC_VERSION_MAJOR < 59)
 #endif
+#ifndef FF_API_NEXT
+#define FF_API_NEXT              (LIBAVCODEC_VERSION_MAJOR < 59)
+#endif
 
 
 #endif /* AVCODEC_VERSION_H */