Fix crash when the pixel format is unknown in frames (#794)

### Fix crash when the pixel format is unknown in frames

### Linked issues
n/a

### Summarize your change.
Save the pixel format when the media is opened and use that as fallback
if the pixel format of some frames can not be detected. This assumes
that there is a pixel format when opening the file and if it does not
have one, it will fail at that point before getting to
`decodeImageAtFrame`.

### Describe the reason for the change.
OpenRV was crashing on some AV1 media because the pixel format was
unknown for all the frames.

### Describe what you have tested and on which operating system.
MacOS

### Add a list of changes, and note any that might need special
attention during the review.

### If possible, provide screenshots.

Signed-off-by: Cédrik Fuoco <[email protected]>

Author: cedrik-fuoco-adsk

src/lib/image/MovieFFMpeg/CMakeLists.txt

@@ -24,14 +24,13 @@ TARGET_INCLUDE_DIRECTORIES(
 
 TARGET_LINK_LIBRARIES(
   ${_target}
-  PUBLIC TwkMovie
+  PUBLIC TwkMovie ffmpeg::avutil
   PRIVATE mp4v2Utils
           Boost::filesystem
           TwkUtil
           TwkFB
           ffmpeg::avcodec
           ffmpeg::avformat
-          ffmpeg::avutil
           ffmpeg::swscale
 )
 

src/lib/image/MovieFFMpeg/MovieFFMpeg.cpp

@@ -1480,6 +1480,7 @@ namespace TwkMovie
                 avcodec_free_context(avCodecContext);
                 return false;
             }
+            m_pxlFormatOnOpen = nativeFormat;
         }
 
         //
@@ -3912,6 +3913,26 @@ namespace TwkMovie
         AVPixelFormat nativeFormat = videoCodecContext->sw_pix_fmt;
         outFrame->format = nativeFormat;
         const AVPixFmtDescriptor* desc = av_pix_fmt_desc_get(nativeFormat);
+        if (!desc && nativeFormat == AV_PIX_FMT_NONE)
+        {
+            static bool warned = false;
+            if (!warned)
+            {
+                std::cout << "WARNING: FFmpeg detected pixel format "
+                             "AV_PIX_FMT_NONE for frames in "
+                          << m_filename << ". Using fallback pixel format: "
+                          << av_get_pix_fmt_name(m_pxlFormatOnOpen)
+                          << std::endl;
+                warned = true;
+            }
+            // Use the pixel format detected when the file was opened as a
+            // fallback. Assumes that m_pxlFormatOnOpen is set because the file
+            // was opened.
+            outFrame->format = m_pxlFormatOnOpen;
+            nativeFormat = m_pxlFormatOnOpen;
+            desc = av_pix_fmt_desc_get(nativeFormat);
+        }
+
         int bitSize = desc->comp[0].depth - desc->comp[0].shift;
         int numPlanes = 0;
         bool hasAlpha = (desc->flags & AV_PIX_FMT_FLAG_ALPHA);

src/lib/image/MovieFFMpeg/MovieFFMpeg/MovieFFMpeg.h

@@ -11,6 +11,10 @@
 #include <TwkMovie/MovieWriter.h>
 #include <TwkMovie/MovieIO.h>
 #include <stdint.h>
+extern "C"
+{
+#include <libavutil/pixfmt.h>
+}
 
 //
 // AVClass Forward Declaration Placeholders
@@ -284,6 +288,7 @@ namespace TwkMovie
         AudioState* m_audioState;
         bool m_cloning{false};
         bool m_mustReadFirstFrame{false};
+        AVPixelFormat m_pxlFormatOnOpen{AV_PIX_FMT_NONE};
 
         friend class ContextPool;
     };