lavc: deprecate avcodec_get_context_defaults3()

This function is supposed to "reset" a codec context to a clean state so
that it can be opened again. The only reason it exists is to allow using
AVStream.codec as a decoding context (after it was already
opened/used/closed by avformat_find_stream_info()). Since that behaviour
is now deprecated, there is no reason for this function to exist
anymore.

libavcodec/avcodec.h

@@ -3619,7 +3619,6 @@ void avcodec_register_all(void);
  *              important mainly for encoders, e.g. libx264).
  *
  * @return An AVCodecContext filled with default values or NULL on failure.
- * @see avcodec_get_context_defaults
  */
 AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);
 
@@ -3629,16 +3628,14 @@ AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);
  */
 void avcodec_free_context(AVCodecContext **avctx);
 
+#if FF_API_GET_CONTEXT_DEFAULTS
 /**
- * Set the fields of the given AVCodecContext to default values corresponding
+ * @deprecated This function should not be used, as closing and opening a codec
- * to the given codec (defaults may be codec-dependent).
+ * context multiple time is not supported. A new codec context should be
- *
+ * allocated for each new use.
- * Do not call this function if a non-NULL codec has been passed
- * to avcodec_alloc_context3() that allocated this AVCodecContext.
- * If codec is non-NULL, it is illegal to call avcodec_open2() with a
- * different codec on this AVCodecContext.
  */
 int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec);
+#endif
 
 /**
  * Get the AVClass for AVCodecContext. It can be used in combination with
@@ -3741,9 +3738,8 @@ int avcodec_parameters_to_context(AVCodecContext *codec,
  * @param avctx The context to initialize.
  * @param codec The codec to open this context for. If a non-NULL codec has been
  *              previously passed to avcodec_alloc_context3() or
- *              avcodec_get_context_defaults3() for this context, then this
+ *              for this context, then this parameter MUST be either NULL or
- *              parameter MUST be either NULL or equal to the previously passed
+ *              equal to the previously passed codec.
- *              codec.
  * @param options A dictionary filled with AVCodecContext and codec-private options.
  *                On return this object will be filled with options that were not found.
  *
@@ -3758,9 +3754,8 @@ int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **op
  * (but not the AVCodecContext itself).
  *
  * Calling this function on an AVCodecContext that hasn't been opened will free
- * the codec-specific data allocated in avcodec_alloc_context3() /
+ * the codec-specific data allocated in avcodec_alloc_context3() with a non-NULL
- * avcodec_get_context_defaults3() with a non-NULL codec. Subsequent calls will
+ * codec. Subsequent calls will do nothing.
- * do nothing.
  */
 int avcodec_close(AVCodecContext *avctx);
 

libavcodec/options.c

@@ -80,7 +80,7 @@ static const AVClass av_codec_context_class = {
     .child_class_next        = codec_child_class_next,
 };
 
-int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec)
+static int init_context_defaults(AVCodecContext *s, const AVCodec *codec)
 {
     memset(s, 0, sizeof(AVCodecContext));
 
@@ -125,6 +125,13 @@ int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec)
     return 0;
 }
 
+#if FF_API_GET_CONTEXT_DEFAULTS
+int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec)
+{
+    return init_context_defaults(s, codec);
+}
+#endif
+
 AVCodecContext *avcodec_alloc_context3(const AVCodec *codec)
 {
     AVCodecContext *avctx= av_malloc(sizeof(AVCodecContext));
@@ -132,7 +139,7 @@ AVCodecContext *avcodec_alloc_context3(const AVCodec *codec)
     if (!avctx)
         return NULL;
 
-    if(avcodec_get_context_defaults3(avctx, codec) < 0){
+    if (init_context_defaults(avctx, codec) < 0) {
         av_free(avctx);
         return NULL;
     }

libavcodec/version.h

@@ -203,5 +203,8 @@
 #ifndef FF_API_COPY_CONTEXT
 #define FF_API_COPY_CONTEXT     (LIBAVCODEC_VERSION_MAJOR < 59)
 #endif
+#ifndef FF_API_GET_CONTEXT_DEFAULTS
+#define FF_API_GET_CONTEXT_DEFAULTS (LIBAVCODEC_VERSION_MAJOR < 59)
+#endif
 
 #endif /* AVCODEC_VERSION_H */