[FFmpeg-cvslog] avcodec/mpegvideo_dec: Notify users of reinit

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Mar 25 09:08:50 2025 +0100| [1d5f660ff662d340ee120734c8ea2423857902b2] | committer: Andreas Rheinhardt

avcodec/mpegvideo_dec: Notify users of reinit

Namely of reinititialization performed by
ff_mpeg_update_thread_context(), so that they can simply
update their own dimension-based buffers accordingly.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1d5f660ff662d340ee120734c8ea2423857902b2
---

 libavcodec/mpegvideo_dec.c | 6 ++++--
 libavcodec/mpegvideodec.h  | 9 +++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c
index 4019b4f0da..75c765218c 100644
--- a/libavcodec/mpegvideo_dec.c
+++ b/libavcodec/mpegvideo_dec.c
@@ -80,7 +80,7 @@ int ff_mpeg_update_thread_context(AVCodecContext *dst,
 {
     MpegEncContext *const s1 = src->priv_data;
     MpegEncContext *const s  = dst->priv_data;
-    int ret;
+    int ret = 0;
 
     if (dst == src)
         return 0;
@@ -102,6 +102,7 @@ int ff_mpeg_update_thread_context(AVCodecContext *dst,
         if (s1->context_initialized) {
             if ((err = ff_mpv_common_init(s)) < 0)
                 return err;
+            ret = 1;
         }
     }
 
@@ -110,6 +111,7 @@ int ff_mpeg_update_thread_context(AVCodecContext *dst,
         s->width  = s1->width;
         if ((ret = ff_mpv_common_frame_size_change(s)) < 0)
             return ret;
+        ret = 1;
     }
 
     s->quarter_sample       = s1->quarter_sample;
@@ -139,7 +141,7 @@ int ff_mpeg_update_thread_context(AVCodecContext *dst,
     memcpy(&s->progressive_sequence, &s1->progressive_sequence,
            (char *) &s1->first_field + sizeof(s1->first_field) - (char *) &s1->progressive_sequence);
 
-    return 0;
+    return ret;
 }
 
 av_cold int ff_mpv_decode_close(AVCodecContext *avctx)
diff --git a/libavcodec/mpegvideodec.h b/libavcodec/mpegvideodec.h
index 6100364715..bc4bc90590 100644
--- a/libavcodec/mpegvideodec.h
+++ b/libavcodec/mpegvideodec.h
@@ -62,6 +62,15 @@ void ff_mpv_frame_end(MpegEncContext *s);
 
 int ff_mpv_export_qp_table(const MpegEncContext *s, AVFrame *f,
                            const MPVPicture *p, int qp_type);
+/**
+ * update_thread_context for mpegvideo-based decoders. It updates
+ * the MPVPictures and generic stream-level parameters. If necessary
+ * (on dimension changes), it also performs reinitialization.
+ *
+ * @retval 1 if a reinitialization happened
+ * @retval 0 on success if no reinitialization happened
+ * @retval "<0" error code
+ */
 int ff_mpeg_update_thread_context(AVCodecContext *dst, const AVCodecContext *src);
 void ff_mpeg_draw_horiz_band(MpegEncContext *s, int y, int h);
 void ff_mpeg_flush(AVCodecContext *avctx);