play music some times produce sigsegv in VideoDecoderFFmpegBase::decode at avcodec_decode_video2

[SGD9919]

class:
VideoDecoderFFmpegBase

part:
ret = avcodec_decode_video2(d.codec_ctx, d.frame, &got_frame_ptr,sendPacket);

debug:
I use qtcreator find d.codec_ctx is 0x0; I got an qt wanning log Audio Decode failed in console
The problem is random, and it is normal for the music file to play again。

may resolve：
check the codec_ctx is null or return false;

I add those in the decode function；I've been testing it for a while
if(!d.codec_ctx||!d.is_open)
{
qWarning("codec context not ready");
return false;
}

deep problem:

in AVDecoderPrivate at line 99;
codec_ctx = avcodec_alloc_context3(NULL);
in ffmpeg introduce：
/**

• Allocate an AVCodecContext and set its fields to default values. The
• resulting struct should be freed with avcodec_free_context().
• @param codec if non-NULL, allocate private data and initialize defaults

•          for the given codec. It is illegal to then call avcodec_open2()
  

•          with a different codec.
  

•          If NULL, then the codec-specific defaults won't be initialized,
  

•          which may result in suboptimal default settings (this is
  

•          important mainly for encoders, e.g. libx264).
  

• @return An AVCodecContext filled with default values or NULL on failure.
  */
  AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);

this function may return null ，but it is not check by any if code。