[FFmpeg-devel] [PATCH] avformat, ffmpeg: deprecate old rotation API

wm4 nfxjfg at googlemail.com
Tue Mar 21 09:42:58 EET 2017


The old "API" that signaled rotation as a metadata value has been
replaced by DISPLAYMATRIX side data quite a while ago.

There is no reason to make muxers/demuxers/API users support both. In
addition, the metadata API is dangerous, as user tags could "leak" into
it, creating unintended features or bugs.

Unfortunately, hacks have been added, that allow the user to override
rotation by setting metadata explicitly, e.g. via

  -metadata:s:v:0 rotate=0

See references to trac #4560. fate-filter-meta-4560-rotate0 tests this.
It's easier to adjust the hack for supporting it than arguing for its
removal, so ffmpeg CLI now explicitly catches this case, and essentially
replaces the "rotate" value with a display matrix side data. (It would
be easier for both user and implementation to create an explicit option
for rotation.)

When the code under FF_API_OLD_ROTATE_API is disabled, one FATE
reference file has to be updated (because "rotate" is not exported
anymore).
---
 cmdutils.c            |  4 ++++
 ffmpeg.c              | 11 ++++++++---
 ffmpeg.h              |  1 +
 ffmpeg_opt.c          | 12 ++++++++----
 libavformat/mov.c     |  2 ++
 libavformat/movenc.c  |  4 ++++
 libavformat/version.h |  3 +++
 7 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/cmdutils.c b/cmdutils.c
index 2373dbf841..594581faa4 100644
--- a/cmdutils.c
+++ b/cmdutils.c
@@ -2097,17 +2097,21 @@ void *grow_array(void *array, int elem_size, int *size, int new_size)
 
 double get_rotation(AVStream *st)
 {
+#if FF_API_OLD_ROTATE_API
     AVDictionaryEntry *rotate_tag = av_dict_get(st->metadata, "rotate", NULL, 0);
+#endif
     uint8_t* displaymatrix = av_stream_get_side_data(st,
                                                      AV_PKT_DATA_DISPLAYMATRIX, NULL);
     double theta = 0;
 
+#if FF_API_OLD_ROTATE_API
     if (rotate_tag && *rotate_tag->value && strcmp(rotate_tag->value, "0")) {
         char *tail;
         theta = av_strtod(rotate_tag->value, &tail);
         if (*tail)
             theta = 0;
     }
+#endif
     if (displaymatrix && !theta)
         theta = -av_display_rotation_get((int32_t*) displaymatrix);
 
diff --git a/ffmpeg.c b/ffmpeg.c
index dcb7720241..6dc36c9e0a 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -50,6 +50,7 @@
 #include "libavutil/internal.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/dict.h"
+#include "libavutil/display.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/avstring.h"
@@ -3051,9 +3052,6 @@ static int init_output_stream_streamcopy(OutputStream *ost)
             const AVPacketSideData *sd_src = &ist->st->side_data[i];
             AVPacketSideData *sd_dst = &ost->st->side_data[ost->st->nb_side_data];
 
-            if (ost->rotate_overridden && sd_src->type == AV_PKT_DATA_DISPLAYMATRIX)
-                continue;
-
             sd_dst->data = av_malloc(sd_src->size);
             if (!sd_dst->data)
                 return AVERROR(ENOMEM);
@@ -3064,6 +3062,13 @@ static int init_output_stream_streamcopy(OutputStream *ost)
         }
     }
 
+    if (ost->rotate_overridden) {
+        uint8_t *sd = av_stream_new_side_data(ost->st, AV_PKT_DATA_DISPLAYMATRIX,
+                                              sizeof(int32_t) * 9);
+        if (sd)
+            av_display_rotation_set((int32_t *)sd, -ost->rotate_override_value);
+    }
+
     ost->parser = av_parser_init(par_dst->codec_id);
     ost->parser_avctx = avcodec_alloc_context3(NULL);
     if (!ost->parser_avctx)
diff --git a/ffmpeg.h b/ffmpeg.h
index c3ed6ced78..4d0456c1fb 100644
--- a/ffmpeg.h
+++ b/ffmpeg.h
@@ -475,6 +475,7 @@ typedef struct OutputStream {
     int force_fps;
     int top_field_first;
     int rotate_overridden;
+    double rotate_override_value;
 
     AVRational frame_aspect_ratio;
 
diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
index fc885dfac3..ffe1abdb38 100644
--- a/ffmpeg_opt.c
+++ b/ffmpeg_opt.c
@@ -2549,8 +2549,6 @@ loop_end:
             av_dict_copy(&output_streams[i]->st->metadata, ist->st->metadata, AV_DICT_DONT_OVERWRITE);
             if (!output_streams[i]->stream_copy) {
                 av_dict_set(&output_streams[i]->st->metadata, "encoder", NULL, 0);
-                if (ist->autorotate)
-                    av_dict_set(&output_streams[i]->st->metadata, "rotate", NULL, 0);
             }
         }
 
@@ -2640,9 +2638,15 @@ loop_end:
             for (j = 0; j < oc->nb_streams; j++) {
                 ost = output_streams[nb_output_streams - oc->nb_streams + j];
                 if ((ret = check_stream_specifier(oc, oc->streams[j], stream_spec)) > 0) {
-                    av_dict_set(&oc->streams[j]->metadata, o->metadata[i].u.str, *val ? val : NULL, 0);
                     if (!strcmp(o->metadata[i].u.str, "rotate")) {
-                        ost->rotate_overridden = 1;
+                        char *tail;
+                        double theta = av_strtod(val, &tail);
+                        if (!*tail) {
+                            ost->rotate_overridden = 1;
+                            ost->rotate_override_value = theta;
+                        }
+                    } else {
+                        av_dict_set(&oc->streams[j]->metadata, o->metadata[i].u.str, *val ? val : NULL, 0);
                     }
                 } else if (ret < 0)
                     exit_program(1);
diff --git a/libavformat/mov.c b/libavformat/mov.c
index f7dd2502c5..9581c965a3 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4030,6 +4030,7 @@ static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
             for (j = 0; j < 3; j++)
                 sc->display_matrix[i * 3 + j] = res_display_matrix[i][j];
 
+#if FF_API_OLD_ROTATE_API
         rotate = av_display_rotation_get(sc->display_matrix);
         if (!isnan(rotate)) {
             char rotate_buf[64];
@@ -4039,6 +4040,7 @@ static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
             snprintf(rotate_buf, sizeof(rotate_buf), "%g", rotate);
             av_dict_set(&st->metadata, "rotate", rotate_buf, 0);
         }
+#endif
     }
 
     // transform the display width/height according to the matrix
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index a28621080d..c049aa972f 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -2496,19 +2496,23 @@ static int mov_write_tkhd_tag(AVIOContext *pb, MOVMuxContext *mov,
     avio_wb16(pb, 0); /* reserved */
 
     /* Matrix structure */
+#if FF_API_OLD_ROTATE_API
     if (st && st->metadata) {
         AVDictionaryEntry *rot = av_dict_get(st->metadata, "rotate", NULL, 0);
         rotation = (rot && rot->value) ? atoi(rot->value) : 0;
     }
+#endif
     if (display_matrix) {
         for (i = 0; i < 9; i++)
             avio_wb32(pb, display_matrix[i]);
+#if FF_API_OLD_ROTATE_API
     } else if (rotation == 90) {
         write_matrix(pb,  0,  1, -1,  0, track->par->height, 0);
     } else if (rotation == 180) {
         write_matrix(pb, -1,  0,  0, -1, track->par->width, track->par->height);
     } else if (rotation == 270) {
         write_matrix(pb,  0, -1,  1,  0, 0, track->par->width);
+#endif
     } else {
         write_matrix(pb,  1,  0,  0,  1, 0, 0);
     }
diff --git a/libavformat/version.h b/libavformat/version.h
index bfc42e3f15..2ff4e4e9d0 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -94,6 +94,9 @@
 #ifndef FF_API_LAVF_KEEPSIDE_FLAG
 #define FF_API_LAVF_KEEPSIDE_FLAG       (LIBAVFORMAT_VERSION_MAJOR < 58)
 #endif
+#ifndef FF_API_OLD_ROTATE_API
+#define FF_API_OLD_ROTATE_API           (LIBAVFORMAT_VERSION_MAJOR < 58)
+#endif
 
 
 #ifndef FF_API_R_FRAME_RATE
-- 
2.11.0



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