On Wed, Mar 1, 2023 at 2:07 PM James Almer <jamr...@gmail.com> wrote: > > On 3/1/2023 3:50 PM, Jeremy Dorfman wrote: > > null pointer arithmetic is undefined behavior in C. > > --- > > libavcodec/h264dec.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c > > index 2d691731c5..ef698f2630 100644 > > --- a/libavcodec/h264dec.c > > +++ b/libavcodec/h264dec.c > > @@ -912,8 +912,8 @@ static int finalize_frame(H264Context *h, AVFrame *dst, H264Picture *out, int *g > > av_log(h->avctx, AV_LOG_DEBUG, "Duplicating field %d to fill missing\n", field); > > > > for (p = 0; p<4; p++) { > > - dst_data[p] = f->data[p] + (field^1)*f->linesize[p]; > > - src_data[p] = f->data[p] + field *f->linesize[p]; > > + dst_data[p] = f->data[p] ? f->data[p] + (field^1)*f->linesize[p] : NULL; > > + src_data[p] = f->data[p] ? f->data[p] + field *f->linesize[p] : NULL; > > linesizes[p] = 2*f->linesize[p]; > > } > > Probably cleaner and clearer to do it like this: > > dst_data[p] = FF_PTR_ADD(f->data[p], (field^1)*f->linesize[p]); > src_data[p] = FF_PTR_ADD(f->data[p], field *f->linesize[p]);
Thank you for the feedback. That seems reasonable to me; I wasn't aware of FF_PTR_ADD. --- libavcodec/h264dec.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c index 2d691731c5..0ac04baa4d 100644 --- a/libavcodec/h264dec.c +++ b/libavcodec/h264dec.c @@ -31,6 +31,7 @@ #include "libavutil/avassert.h" #include "libavutil/imgutils.h" +#include "libavutil/internal.h" #include "libavutil/opt.h" #include "libavutil/thread.h" #include "libavutil/video_enc_params.h" @@ -912,8 +913,8 @@ static int finalize_frame(H264Context *h, AVFrame *dst, H264Picture *out, int *g av_log(h->avctx, AV_LOG_DEBUG, "Duplicating field %d to fill missing\n", field); for (p = 0; p<4; p++) { - dst_data[p] = f->data[p] + (field^1)*f->linesize[p]; - src_data[p] = f->data[p] + field *f->linesize[p]; + dst_data[p] = FF_PTR_ADD(f->data[p], (field^1)*f->linesize[p]); + src_data[p] = FF_PTR_ADD(f->data[p], field *f->linesize[p]); linesizes[p] = 2*f->linesize[p]; } _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".