lavc: deprecate unused AVCodecContext.stream_codec_tag

libavcodec/avcodec.h

@@ -1081,13 +1081,13 @@ typedef struct AVCodecContext {
      */
     unsigned int codec_tag;
 
+#if FF_API_STREAM_CODEC_TAG
     /**
-     * fourcc from the AVI stream header (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
+     * @deprecated this field is unused
-     * This is used to work around some encoder bugs.
-     * - encoding: unused
-     * - decoding: Set by user, will be converted to uppercase by libavcodec during init.
      */
+    attribute_deprecated
     unsigned int stream_codec_tag;
+#endif
 
     void *priv_data;
 

libavcodec/mpegvideo.c

@@ -1288,8 +1288,6 @@ av_cold int ff_mpv_common_init(MpegEncContext *s)
     /* convert fourcc to upper case */
     s->codec_tag          = avpriv_toupper4(s->avctx->codec_tag);
 
-    s->stream_codec_tag   = avpriv_toupper4(s->avctx->stream_codec_tag);
-
     FF_ALLOCZ_OR_GOTO(s->avctx, s->picture,
                       MAX_PICTURE_COUNT * sizeof(Picture), fail);
     for (i = 0; i < MAX_PICTURE_COUNT; i++) {

libavcodec/options_table.h

@@ -308,7 +308,9 @@ static const AVOption avcodec_options[] = {
 {"simple", "use mbcmp (default)", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MB_DECISION_SIMPLE }, INT_MIN, INT_MAX, V|E, "mbd"},
 {"bits", "use fewest bits", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MB_DECISION_BITS }, INT_MIN, INT_MAX, V|E, "mbd"},
 {"rd", "use best rate distortion", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MB_DECISION_RD }, INT_MIN, INT_MAX, V|E, "mbd"},
+#if FF_API_STREAM_CODEC_TAG
 {"stream_codec_tag", NULL, OFFSET(stream_codec_tag), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX},
+#endif
 {"sc_threshold", "scene change threshold", OFFSET(scenechange_threshold), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, V|E},
 #if FF_API_MPV_OPT
 {"lmin", "deprecated, use encoder private options instead", OFFSET(lmin), AV_OPT_TYPE_INT, {.i64 =  0 }, 0, INT_MAX, V|E},

libavcodec/version.h

@@ -162,5 +162,8 @@
 #ifndef FF_API_MPV_OPT
 #define FF_API_MPV_OPT           (LIBAVCODEC_VERSION_MAJOR < 59)
 #endif
+#ifndef FF_API_STREAM_CODEC_TAG
+#define FF_API_STREAM_CODEC_TAG  (LIBAVCODEC_VERSION_MAJOR < 59)
+#endif
 
 #endif /* AVCODEC_VERSION_H */