avcodec YUV to RGB

问题

I'm trying to convert an YUV frame to RGB using libswscale.

Here is my code :

AVFrame *RGBFrame;
SwsContext *ConversionContext;

ConversionContext = sws_getCachedContext(NULL, FrameWidth, FrameHeight, AV_PIX_FMT_YUV420P, FrameWidth, FrameHeight, AV_PIX_FMT_RGB24, SWS_BILINEAR, 0, 0, 0);
RGBFrame = av_frame_alloc();

avpicture_fill((AVPicture *)RGBFrame, &FillVect[0], AV_PIX_FMT_RGB24, FrameWidth, FrameHeight);

sws_scale(ConversionContext, VideoFrame->data, VideoFrame->linesize, 0, VideoFrame->height, RGBFrame->data, RGBFrame->linesize);

My program do SEGFAULT on the sws_scale function.

VideoFrame is an AVFrame struct who hold my decoded frame.

I think this is because the YUV frame come from avcodec_decode_video2, which return an array like this :

VideoFrame->data[0] // Y array, linesize = frame width
VideoFrame->data[1] // U array, linesize = frame width/2
VideoFrame->data[2] // V array, linesize = frame width/2

While YUV420P have theoretically only one plane (according to Wikipedia, YUV420P is a planar format, then Y, U, V data are grouped together). So, i don't know how to proceed to convert my array where Y, U, V data are separated into RGB24, using swscale.

Please help me, thanks :)

回答1:

av_frame_alloc only allocates memory for the frame object itself, it does not allocate memory to store the image data. Have you done:

FillVect.resize( avpicture_get_size( PIX_FMT_RGB24, FrameWidth, FrameHeight ) );

somewhere in your code before calling avpicture_fill? Or some other way to make sure FillVect allocates enough memory to keep the whole decoded picture?

Did you try to run it under valgrind to see what exactly trigges SEGFAULT?

来源：https://stackoverflow.com/questions/24970182/avcodec-yuv-to-rgb