[FFmpeg-devel] [PATCH 1/4] lavu/frame: allow calling av_frame_make_writable() on non-refcounted frames

[Anton Khirnov]

This is an easy way to make a refcounted frame from a non-refcounted
one.
---
 doc/APIchanges      | 5 +++++
 libavutil/frame.c   | 3 ---
 libavutil/frame.h   | 3 ++-
 libavutil/version.h | 2 +-
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index f9a1484bbc..4e218af94e 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -14,6 +14,11 @@ libavutil:     2021-04-27
 
 API changes, most recent first:
 
+2022-07-xx - xxxxxxxxxx - lavu 57.30.100 - frame.h
+  av_frame_make_writable() may now be called on non-refcounted
+  frames and will make a refcounted copy out of them.
+  Previously an error was returned in such cases.
+
 -------- 8< --------- FFmpeg 5.1 was cut here -------- 8< ---------
 
 2022-06-12 - 7cae3d8b76 - lavf 59.25.100 - avio.h
diff --git a/libavutil/frame.c b/libavutil/frame.c
index 4c16488c66..7408817e1f 100644
--- a/libavutil/frame.c
+++ b/libavutil/frame.c
@@ -542,9 +542,6 @@ int av_frame_make_writable(AVFrame *frame)
     AVFrame tmp;
     int ret;
 
-    if (!frame->buf[0])
-        return AVERROR(EINVAL);
-
     if (av_frame_is_writable(frame))
         return 0;
 
diff --git a/libavutil/frame.h b/libavutil/frame.h
index 33fac2054c..cc55d67e3c 100644
--- a/libavutil/frame.h
+++ b/libavutil/frame.h
@@ -818,7 +818,8 @@ int av_frame_is_writable(AVFrame *frame);
  * Ensure that the frame data is writable, avoiding data copy if possible.
  *
  * Do nothing if the frame is writable, allocate new buffers and copy the data
- * if it is not.
+ * if it is not. Non-refcounted frames behave as non-writable, i.e. a copy
+ * is always made.
  *
  * @return 0 on success, a negative AVERROR on error.
  *
diff --git a/libavutil/version.h b/libavutil/version.h
index f185322550..734d3f8330 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  29
+#define LIBAVUTIL_VERSION_MINOR  30
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.34.1