avcodec, avformat: deprecate anything related to side data merging

This patch deprecates anything that has to do with merging/splitting
side data. Automatic side data merging (and splitting), as well as all
API symbols involved in it, are removed completely.

Two FF_API_ defines are dedicated to deprecating API symbols related to
this: FF_API_MERGE_SD_API removes av_packet_split/merge_side_data in
libavcodec, and FF_API_LAVF_KEEPSIDE_FLAG deprecates
AVFMT_FLAG_KEEP_SIDE_DATA in libavformat.

Since it was claimed that changing the default from merging side data to
not doing it is an ABI change, there are two additional FF_API_ defines,
which stop using the side data merging/splitting by default (and remove
any code in avformat/avcodec doing this): FF_API_MERGE_SD in libavcodec,
and FF_API_LAVF_MERGE_SD in libavformat.

It is very much intended that FF_API_MERGE_SD and FF_API_LAVF_MERGE_SD
are quickly defined to 0 in the next ABI bump, while the API symbols are
retained for a longer time for the sake of compatibility.
AVFMT_FLAG_KEEP_SIDE_DATA will (very much intentionally) do nothing for
most of the time it will still be defined. Keep in mind that no code
exists that actually tries to unset this flag for any reason, nor does
such code need to exist. Code setting this flag explicitly will work as
before. Thus it's ok for AVFMT_FLAG_KEEP_SIDE_DATA to do nothing once
side data merging has been removed from libavformat.

In order to avoid that anyone in the future does this incorrectly, here
is a small guide how to update the internal code on bumps:

- next ABI bump (probably soon):
  - define FF_API_LAVF_MERGE_SD to 0, and remove all code covered by it
  - define FF_API_MERGE_SD to 0, and remove all code covered by it
- next API bump (typically two years in the future or so):
  - define FF_API_LAVF_KEEPSIDE_FLAG to 0, and remove all code covered
    by it
  - define FF_API_MERGE_SD_API to 0, and remove all code covered by it

This forces anyone who actually wants packet side data to temporarily
use deprecated API to get it all. If you ask me, this is batshit fucked
up crazy, but it's how we roll. Making AVFMT_FLAG_KEEP_SIDE_DATA to be
set by default was rejected as an ABI change, so I'm going all the way
to get rid of this once and for all.

Reviewed-by: James Almer <jamrial@gmail.com>
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>

5 files changed, 28 insertions, 2 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 4c1b18e002..4ab217dc17 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1468,7 +1468,9 @@ typedef struct AVFormatContext {
 #define AVFMT_FLAG_MP4A_LATM    0x8000 ///< Enable RTP MP4A-LATM payload
 #define AVFMT_FLAG_SORT_DTS    0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
 #define AVFMT_FLAG_PRIV_OPT    0x20000 ///< Enable use of private options by delaying codec open (this could be made default once all code is converted)
-#define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate.
+#if FF_API_LAVF_KEEPSIDE_FLAG
+#define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate. Deprecated, will be the default.
+#endif
 #define AVFMT_FLAG_FAST_SEEK   0x80000 ///< Enable fast, but inaccurate seeks for some formats
 #define AVFMT_FLAG_SHORTEST   0x100000 ///< Stop muxing when the shortest stream stops.
 #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Wait for packet data before writing a header, and add bitstream filters as requested by the muxer
diff --git a/libavformat/mux.c b/libavformat/mux.c
index e500531789..11b09f1b6e 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -752,7 +752,11 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
         }
     }
 
+#if FF_API_LAVF_MERGE_SD
+FF_DISABLE_DEPRECATION_WARNINGS
     did_split = av_packet_split_side_data(pkt);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
 
     if (!s->internal->header_written) {
         ret = s->internal->write_header_ret ? s->internal->write_header_ret : write_header_internal(s);
@@ -777,8 +781,12 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
     }
 
 fail:
+#if FF_API_LAVF_MERGE_SD
+FF_DISABLE_DEPRECATION_WARNINGS
     if (did_split)
         av_packet_merge_side_data(pkt);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
 
     if (ret < 0) {
         pkt->pts = pts_backup;
@@ -875,8 +883,12 @@ static int do_packet_auto_bsf(AVFormatContext *s, AVPacket *pkt) {
         }
     }
 
+#if FF_API_LAVF_MERGE_SD
+FF_DISABLE_DEPRECATION_WARNINGS
     if (st->internal->nb_bsfcs)
         av_packet_split_side_data(pkt);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
 
     for (i = 0; i < st->internal->nb_bsfcs; i++) {
         AVBSFContext *ctx = st->internal->bsfcs[i];
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index a537dda95e..0c1915d6d4 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -48,7 +48,9 @@ static const AVOption avformat_options[] = {
 {"igndts", "ignore dts", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_IGNDTS }, INT_MIN, INT_MAX, D, "fflags"},
 {"discardcorrupt", "discard corrupted frames", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_DISCARD_CORRUPT }, INT_MIN, INT_MAX, D, "fflags"},
 {"sortdts", "try to interleave outputted packets by dts", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_SORT_DTS }, INT_MIN, INT_MAX, D, "fflags"},
+#if FF_API_LAVF_KEEPSIDE_FLAG
 {"keepside", "don't merge side data", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_KEEP_SIDE_DATA }, INT_MIN, INT_MAX, D, "fflags"},
+#endif
 {"fastseek", "fast but inaccurate seeks", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_FAST_SEEK }, INT_MIN, INT_MAX, D, "fflags"},
 {"latm", "enable RTP MP4A-LATM payload", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_MP4A_LATM }, INT_MIN, INT_MAX, E, "fflags"},
 {"nobuffer", "reduce the latency introduced by optional buffering", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOBUFFER }, 0, INT_MAX, D, "fflags"},
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 37d7024465..8227d1bbe1 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1675,8 +1675,12 @@ FF_ENABLE_DEPRECATION_WARNINGS
             st->inject_global_side_data = 0;
         }
 
+#if FF_API_LAVF_MERGE_SD
+FF_DISABLE_DEPRECATION_WARNINGS
         if (!(s->flags & AVFMT_FLAG_KEEP_SIDE_DATA))
             av_packet_merge_side_data(pkt);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
     }
 
     av_opt_get_dict_val(s, "metadata", AV_OPT_SEARCH_CHILDREN, &metadata);
diff --git a/libavformat/version.h b/libavformat/version.h
index dc689d45fb..bfc42e3f15 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -33,7 +33,7 @@
 // Also please add any ticket numbers that you believe might be affected here
 #define LIBAVFORMAT_VERSION_MAJOR  57
 #define LIBAVFORMAT_VERSION_MINOR  66
-#define LIBAVFORMAT_VERSION_MICRO 104
+#define LIBAVFORMAT_VERSION_MICRO 105
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \
@@ -88,6 +88,12 @@
 #ifndef FF_API_HLS_WRAP
 #define FF_API_HLS_WRAP                 (LIBAVFORMAT_VERSION_MAJOR < 58)
 #endif
+#ifndef FF_API_LAVF_MERGE_SD
+#define FF_API_LAVF_MERGE_SD            (LIBAVFORMAT_VERSION_MAJOR < 58)
+#endif
+#ifndef FF_API_LAVF_KEEPSIDE_FLAG
+#define FF_API_LAVF_KEEPSIDE_FLAG       (LIBAVFORMAT_VERSION_MAJOR < 58)
+#endif
 
 
 #ifndef FF_API_R_FRAME_RATE