Fix building with newer FFmpeg

Index: src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp
--- src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp.orig
+++ src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp
@@ -51,7 +51,11 @@ FFmpegDecoderVideo::~FFmpegDecoderVideo()
 
     if (m_context)
     {
+#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(61, 3, 100)
         avcodec_close(m_context);
+#else
+        avcodec_free_context(&m_context);
+#endif
     }
 
     OSG_INFO<<"Destructed FFmpegDecoderVideo"<<std::endl;
@@ -62,7 +66,9 @@ FFmpegDecoderVideo::~FFmpegDecoderVideo()
 void FFmpegDecoderVideo::open(AVStream * const stream)
 {
     m_stream = stream;
-    m_context = stream->codec;
+    m_codecpar = stream->codecpar;
+    const AVCodec* p_codec = avcodec_find_decoder(m_codecpar->codec_id);
+    m_context = avcodec_alloc_context3(p_codec);
 
     // Trust the video size given at this point
     // (avcodec_open seems to sometimes return a 0x0 size)
@@ -74,11 +80,7 @@ void FFmpegDecoderVideo::open(AVStream * const stream)
     m_alpha_channel = (m_context->pix_fmt == AV_PIX_FMT_YUVA420P);
 
     // Find out the framerate
-    #if LIBAVCODEC_VERSION_MAJOR >= 56
     m_frame_rate = av_q2d(stream->avg_frame_rate);
-    #else
-    m_frame_rate = av_q2d(stream->r_frame_rate);
-    #endif
 
     // Find the decoder for the video stream
     m_codec = avcodec_find_decoder(m_context->codec_id);
@@ -99,11 +101,12 @@ void FFmpegDecoderVideo::open(AVStream * const stream)
 
     // Allocate converted RGB frame
     m_frame_rgba.reset(av_frame_alloc());
-    m_buffer_rgba[0].resize(avpicture_get_size(AV_PIX_FMT_RGB24, width(), height()));
+    m_buffer_rgba[0].resize(av_image_get_buffer_size(AV_PIX_FMT_RGB24, width(), height(), 1));
     m_buffer_rgba[1].resize(m_buffer_rgba[0].size());
 
     // Assign appropriate parts of the buffer to image planes in m_frame_rgba
-    avpicture_fill((AVPicture *) (m_frame_rgba).get(), &(m_buffer_rgba[0])[0], AV_PIX_FMT_RGB24, width(), height());
+    AVFrame *avf = m_frame_rgba.get();
+    av_image_fill_arrays(avf->data, avf->linesize, &(m_buffer_rgba[0])[0], AV_PIX_FMT_RGB24, width(), height(), 1);
 
     // Override get_buffer()/release_buffer() from codec context in order to retrieve the PTS of each frame.
     m_context->opaque = this;
@@ -169,7 +172,7 @@ void FFmpegDecoderVideo::decodeLoop()
             int frame_finished = 0;
 
             // We want to use the entire packet since some codecs will require extra information for decoding
-            const int bytes_decoded = avcodec_decode_video2(m_context, m_frame.get(), &frame_finished, &(packet.packet));
+            const int bytes_decoded = avcodec_receive_frame(m_context, m_frame.get());
 
             if (bytes_decoded < 0)
                 throw std::runtime_error("avcodec_decode_video failed()");
@@ -180,40 +183,9 @@ void FFmpegDecoderVideo::decodeLoop()
             // Publish the frame if we have decoded a complete frame
             if (frame_finished)
             {
-#if LIBAVCODEC_VERSION_INT <= AV_VERSION_INT(57,24,102)
-                //ffmpeg-3.0 and below
-                AVRational timebase;
                 // Find out the frame pts
                 if (m_frame->pts != int64_t(AV_NOPTS_VALUE))
                 {
-                    pts = m_frame->pts;
-                    timebase = m_context->time_base;
-                }
-                else if (packet.packet.dts == int64_t(AV_NOPTS_VALUE) &&
-                        m_frame->opaque != 0 &&
-                        *reinterpret_cast<const int64_t*>(m_frame->opaque) != int64_t(AV_NOPTS_VALUE))
-                {
-                    pts = *reinterpret_cast<const int64_t*>(m_frame->opaque);
-                    timebase = m_stream->time_base;
-                }
-                else if (packet.packet.dts != int64_t(AV_NOPTS_VALUE))
-                {
-                    pts = packet.packet.dts;
-                    timebase = m_stream->time_base;
-                }
-                else
-                {
-                    pts = 0;
-                    timebase = m_context->time_base;
-                }
-
-                pts *= av_q2d(timebase);
-
-#else
-                //above ffmpeg-3.0
-                // Find out the frame pts
-                if (m_frame->pts != int64_t(AV_NOPTS_VALUE))
-                {
                     pts = av_q2d(m_stream->time_base) * m_frame->pts;
                 }
                 else if (packet.packet.dts == int64_t(AV_NOPTS_VALUE) &&
@@ -230,7 +202,6 @@ void FFmpegDecoderVideo::decodeLoop()
                 {
                     pts = 0;
                 }
-#endif
                 const double synched_pts = m_clocks.videoSynchClock(m_frame.get(), av_q2d(av_inv_q(m_context->framerate)), pts);
                 const double frame_delay = m_clocks.videoRefreshSchedule(synched_pts);
 
@@ -283,7 +254,7 @@ void FFmpegDecoderVideo::findAspectRatio()
     m_pixel_aspect_ratio = ratio;
 }
 
-int FFmpegDecoderVideo::convert(AVPicture *dst, int dst_pix_fmt, AVPicture *src,
+int FFmpegDecoderVideo::convert(AVFrame *dst, int dst_pix_fmt, AVFrame *src,
             int src_pix_fmt, int src_width, int src_height)
 {
     osg::Timer_t startTick = osg::Timer::instance()->tick();
@@ -334,11 +305,11 @@ void FFmpegDecoderVideo::publishFrame(const double del
         return;
 #endif
 
-    AVPicture * const src = (AVPicture *) m_frame.get();
-    AVPicture * const dst = (AVPicture *) m_frame_rgba.get();
+    AVFrame * const src = (AVFrame *) m_frame.get();
+    AVFrame * const dst = (AVFrame *) m_frame_rgba.get();
 
     // Assign appropriate parts of the buffer to image planes in m_frame_rgba
-    avpicture_fill((AVPicture *) (m_frame_rgba).get(), &(m_buffer_rgba[m_writeBuffer])[0], AV_PIX_FMT_RGB24, width(), height());
+    av_image_fill_arrays(dst->data, dst->linesize, &(m_buffer_rgba[m_writeBuffer])[0], AV_PIX_FMT_RGB24, width(), height(), 1);
 
     // Convert YUVA420p (i.e. YUV420p plus alpha channel) using our own routine
 
@@ -370,7 +341,7 @@ void FFmpegDecoderVideo::publishFrame(const double del
 
 
 
-void FFmpegDecoderVideo::yuva420pToRgba(AVPicture * const dst, AVPicture * const src, int width, int height)
+void FFmpegDecoderVideo::yuva420pToRgba(AVFrame * const dst, AVFrame * const src, int width, int height)
 {
     convert(dst, AV_PIX_FMT_RGB24, src, m_context->pix_fmt, width, height);