api: make frame copying const for source frame

Don't bump version, as API is not broken. Breaks ABI, but we do not set
the SONAME tag, meaning we don't have an ABI version.

Change-Id: I5bc436f00e20eca7a789b0d8f5863d6622f82d0f
Reviewed-by: Sebastien Blin <sebastien.blin@savoirfairelinux.com>

src/client/videomanager.cpp

@@ -53,7 +53,7 @@ MediaFrame::MediaFrame()
 }
 
 void
-MediaFrame::copyFrom(MediaFrame& o)
+MediaFrame::copyFrom(const MediaFrame& o)
 {
     reset();
     av_frame_ref(frame_.get(), o.frame_.get());
@@ -80,7 +80,7 @@ VideoFrame::reset() noexcept
 }
 
 void
-VideoFrame::copyFrom(VideoFrame& o)
+VideoFrame::copyFrom(const VideoFrame& o)
 {
     MediaFrame::copyFrom(o);
     ptr_ = o.ptr_;

src/dring/videomanager_interface.h

@@ -79,7 +79,7 @@ public:
     AVFrame* pointer() const noexcept { return frame_.get(); }
 
     // Fill this MediaFrame with data from o
-    void copyFrom(MediaFrame& o);
+    void copyFrom(const MediaFrame& o);
 
     // Reset internal buffers (return to an empty MediaFrame)
     virtual void reset() noexcept;
@@ -100,7 +100,7 @@ public:
     void reset() noexcept override;
 
     // Fill this VideoFrame with data from o
-    void copyFrom(VideoFrame& o);
+    void copyFrom(const VideoFrame& o);
 
     // Return frame size in bytes
     std::size_t size() const noexcept;