lavc: add a FF_API_REQUEST_CHANNELS deprecation macro

And hide request_channels AVOption under it.

libavcodec/avcodec.h

@@ -2590,7 +2590,7 @@ typedef struct AVCodecContext {
      */
     int64_t timecode_frame_start;
 
-#if LIBAVCODEC_VERSION_MAJOR < 53
+#if FF_API_REQUEST_CHANNELS
     /**
      * Decoder should decode to this many channels if it can (0 for default)
      * - encoding: unused

libavcodec/options.c

@@ -408,7 +408,9 @@ static const AVOption options[]={
 {"timecode_frame_start", "GOP timecode frame start number, in non drop frame format", OFFSET(timecode_frame_start), FF_OPT_TYPE_INT64, 0, 0, INT64_MAX, V|E},
 {"drop_frame_timecode", NULL, 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_DROP_FRAME_TIMECODE, INT_MIN, INT_MAX, V|E, "flags2"},
 {"non_linear_q", "use non linear quantizer", 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_NON_LINEAR_QUANT, INT_MIN, INT_MAX, V|E, "flags2"},
+#if FF_API_REQUEST_CHANNELS
 {"request_channels", "set desired number of audio channels", OFFSET(request_channels), FF_OPT_TYPE_INT, DEFAULT, 0, INT_MAX, A|D},
+#endif
 {"drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), FF_OPT_TYPE_FLOAT, 1.0, 0.0, 1.0, A|D},
 {"reservoir", "use bit reservoir", 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_BIT_RESERVOIR, INT_MIN, INT_MAX, A|E, "flags2"},
 {"mbtree", "use macroblock tree ratecontrol (x264 only)", 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_MBTREE, INT_MIN, INT_MAX, V|E, "flags2"},

libavcodec/version.h

@@ -83,5 +83,8 @@
 #ifndef FF_API_ANTIALIAS_ALGO
 #define FF_API_ANTIALIAS_ALGO   (LIBAVCODEC_VERSION_MAJOR < 54)
 #endif
+#ifndef FF_API_REQUEST_CHANNELS
+#define FF_API_REQUEST_CHANNELS (LIBAVCODEC_VERSION_MAJOR < 53)
+#endif
 
 #endif /* AVCODEC_VERSION_H */