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* [FFmpeg-devel] [PATCH 1/5] avcodec/progressframe: Explain how unnamed union can simplify accesses
@ 2024-04-19 15:58 Andreas Rheinhardt
  2024-04-19 16:07 ` [FFmpeg-devel] [PATCH 2/5] avcodec/hevcdec: Use union for AVFrame* and ProgressFrame Andreas Rheinhardt
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Andreas Rheinhardt @ 2024-04-19 15:58 UTC (permalink / raw)
  To: ffmpeg-devel; +Cc: Andreas Rheinhardt

This relies on the common initial seqence guarantee
(and on C11 support for unnamed members).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
Alternatively, we could rely on type punning via unions and even use
    union {
        AVFrame *const f;
        ProgressFrame pf;
    };

 libavcodec/progressframe.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/libavcodec/progressframe.h b/libavcodec/progressframe.h
index dc841f30d2..428a461659 100644
--- a/libavcodec/progressframe.h
+++ b/libavcodec/progressframe.h
@@ -58,6 +58,18 @@
 
 struct AVCodecContext;
 
+/**
+ * The ProgressFrame structure.
+ * Hint: It is guaranteed that the AVFrame pointer is at the start
+ *       of ProgressFrame. This allows to use an unnamed
+ *       union {
+ *            struct {
+ *                AVFrame *f;
+ *            };
+ *            ProgressFrame pf;
+ *       };
+ *       to simplify accessing the embedded AVFrame.
+ */
 typedef struct ProgressFrame {
     struct AVFrame *f;
     struct ProgressInternal *progress;
-- 
2.40.1

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^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2024-04-20 20:22 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-19 15:58 [FFmpeg-devel] [PATCH 1/5] avcodec/progressframe: Explain how unnamed union can simplify accesses Andreas Rheinhardt
2024-04-19 16:07 ` [FFmpeg-devel] [PATCH 2/5] avcodec/hevcdec: Use union for AVFrame* and ProgressFrame Andreas Rheinhardt
2024-04-19 16:07 ` [FFmpeg-devel] [PATCH 3/5] avcodec/av1dec: Use ProgressFrames Andreas Rheinhardt
2024-04-20 20:22   ` James Almer
2024-04-19 16:07 ` [FFmpeg-devel] [PATCH 4/5] avcodec/av1dec: Make av1_frame_replace() out of av1_frame_ref() Andreas Rheinhardt
2024-04-19 16:07 ` [FFmpeg-devel] [PATCH 5/5] avcodec/vaapi_av1: Use ProgressFrames Andreas Rheinhardt

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