[FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: ensure the display_rotation option is honored (PR #20276)

[James Almer via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #20276 opened by James Almer (jamrial)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20276
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20276.patch

If requested, it should have priotity over any coded value

Fixes trac ticket #11649.


From e90c889ee2cefbe173a2f61e1433b18c33436a0c Mon Sep 17 00:00:00 2001
From: James Almer <jamrial@gmail.com>
Date: Mon, 18 Aug 2025 11:16:23 -0300
Subject: [PATCH 1/2] avcodec/mjpegdec: use ff_frame_new_side_data() to export
 display matrix

Otherwise, the user requested priority of packet side data will be ignored.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/mjpegdec.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 87d1d02077..b6bf1ab224 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -2876,15 +2876,15 @@ the_end:
             AVFrameSideData *sd = NULL;
 
             if (orientation >= 2 && orientation <= 8) {
-                int32_t *matrix;
-
-                sd = av_frame_new_side_data(frame, AV_FRAME_DATA_DISPLAYMATRIX, sizeof(int32_t) * 9);
-                if (!sd) {
+                ret = ff_frame_new_side_data(avctx, frame, AV_FRAME_DATA_DISPLAYMATRIX,
+                                             sizeof(int32_t) * 9, &sd);
+                if (ret < 0) {
                     av_log(avctx, AV_LOG_ERROR, "Could not allocate frame side data\n");
-                    return AVERROR(ENOMEM);
+                    return ret;
                 }
-
-                matrix = (int32_t *)sd->data;
+            }
+            if (sd) {
+                int32_t *matrix = (int32_t *)sd->data;
 
                 switch (orientation) {
                 case 2:
-- 
2.49.1


From 66563b40f34741a725d8bbd17ae352ed109af8b1 Mon Sep 17 00:00:00 2001
From: James Almer <jamrial@gmail.com>
Date: Mon, 18 Aug 2025 12:22:09 -0300
Subject: [PATCH 2/2] fftools/ffmpeg_demux: ensure the display_rotation option
 is honored

If requested, it should have priotity over any coded value.
Fixes ticket #11649.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 fftools/ffmpeg_demux.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index 78d8ff6b7d..a67d71387a 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -67,6 +67,7 @@ typedef struct DemuxStream {
     int                      reinit_filters;
     int                      autorotate;
     int                      apply_cropping;
+    int                      force_display_matrix;
     int                      drop_changed;
 
 
@@ -1183,6 +1184,7 @@ static int add_display_matrix_to_stream(const OptionsContext *o,
                                         AVFormatContext *ctx, InputStream *ist)
 {
     AVStream *st = ist->st;
+    DemuxStream *ds = ds_from_ist(ist);
     AVPacketSideData *sd;
     double rotation = DBL_MAX;
     int hflip = -1, vflip = -1;
@@ -1217,6 +1219,8 @@ static int add_display_matrix_to_stream(const OptionsContext *o,
                            hflip_set ? hflip : 0,
                            vflip_set ? vflip : 0);
 
+    ds->force_display_matrix = 1;
+
     return 0;
 }
 
@@ -1455,6 +1459,13 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st, AVDictiona
     av_dict_set_int(&ds->decoder_opts, "apply_cropping",
                     ds->apply_cropping && ds->apply_cropping != CROP_CONTAINER, 0);
 
+    if (ds->force_display_matrix) {
+        char buf[32];
+        if (av_dict_get(ds->decoder_opts, "side_data_prefer_packet", NULL, 0))
+            snprintf(buf, sizeof(buf), ",");
+        av_strlcat(buf, "displaymatrix", sizeof(buf));
+        av_dict_set(&ds->decoder_opts, "side_data_prefer_packet", buf, AV_DICT_APPEND);
+    }
     /* Attached pics are sparse, therefore we would not want to delay their decoding
      * till EOF. */
     if (ist->st->disposition & AV_DISPOSITION_ATTACHED_PIC)
-- 
2.49.1

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