On Sat, 9 Feb 2013 02:11:31 +0100, Vittorio Giovara <vittorio.giov...@gmail.com> wrote: > So, following up from the discussion on IRC, I think it better to start out > fresh. > > I think I have fixed cropping for the right and bottom offset (with just > minor modifications and only two files touched). > What this patch does is: > 1. keep the video size (width and height) to the full size of the video > surface (in ff_h264_decode_seq_parameter_set() ); > 2. apply the cropping on the picture when the whole frame has been decoded > (near the return value of decode_frame); > 3. apply the cropping one more time on the context when the decoder is > closed (in h264_decode_end() ); > 4. remove the error for the "brainfart cropping". > > Wrt 1, I'm aware that coded_width and coded_height should be used to > represent the full bitstream dimensions, but they are not present in > H264Context; the ones in the AVCodecContext interact in unclear ways (to me > at least) with width and height (see avcodec_set_dimensions); > Wrt 2, this is fine and it's what the h264 specs actually mandate; > Wrt 3, I had to add this because otherwise try_decode_frame would report > incorrect dimensions and subsequent frame decoding would fail. > (wrt 4, I never understood why it was 'brainfart'... theoretically you > could crop any offset in any direction, but oh well) > > I think that other approaches might require a LOT more modifications and > readability would be hindered (imho). > Also, I would like to defend the design choice of applying the cropping at > the end of frame decoding on the picture itself (even if avframe values > become different) because this exactly what cropping is for: decode the > whole frame and display just a portion of it, ignoring anything outside it. > > Finally, this patch fixes half of bug 378 (and does not break FATE). >
Forgot to actually attach the patch? -- Anton Khirnov _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel
