Frame: fix isValid() to work with any HW-encoded frames

Sounds like FFmpeg uses data[3] as a reference to the internal HW frame
ID at the same time, when data[0] still is NULL. At same time
hw_frames_ctx is not a NULL.

Also, add isHwFrame().

Fix #175

Author: h4tr3d

src/avcpp/frame.cpp

@@ -646,12 +646,16 @@ bool FrameCommon::isComplete() const { return m_isComplete; }
 bool FrameCommon::isValid() const {
     return (!isNull() &&
             ((m_raw->data[0] && m_raw->linesize[0]) ||
-             ((m_raw->format == AV_PIX_FMT_VAAPI) && ((intptr_t)m_raw->data[3] > 0)))
-            );
+             ((m_raw->hw_frames_ctx) && ((intptr_t)m_raw->data[3] > 0))));
 }
 
 FrameCommon::operator bool() const { return isValid() && isComplete(); }
 
+bool FrameCommon::isHwFrame() const
+{
+    return !isNull() && !!m_raw->hw_frames_ctx;
+}
+
 uint8_t *FrameCommon::data(size_t plane) {
     if (!m_raw || plane >= size_t(AV_NUM_DATA_POINTERS + m_raw->nb_extended_buf))
         return nullptr;

src/avcpp/frame.h

@@ -110,6 +110,8 @@ class FrameCommon : public FFWrapperPtr<AVFrame>
 
     operator bool() const;
 
+    bool isHwFrame() const;
+
     uint8_t *data(size_t plane = 0);
     const uint8_t *data(size_t plane = 0) const;