[FFmpeg-devel] [RFC PATCH] libavcodec/libopenjpeg: pix fmt selection change

[Michael Bradshaw]

On Tue, Jun 9, 2020 at 6:07 AM <gautamramk at gmail.com> wrote:

> From: Gautam Ramakrishnan <gautamramk at gmail.com>
>
> This patch makes selection of pix_fmt similar to
> that in the native decoder. This makes samples such
> as p0_05.j2k and p1_03.j2k decodable by libopenjpeg.
> ---
>  libavcodec/libopenjpegdec.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/libopenjpegdec.c b/libavcodec/libopenjpegdec.c
> index 344c5ba5a3..f5f208784e 100644
> --- a/libavcodec/libopenjpegdec.c
> +++ b/libavcodec/libopenjpegdec.c
> @@ -272,11 +272,11 @@ static inline void libopenjpeg_copyto8(AVFrame
> *picture, opj_image_t *image) {
>      int *comp_data;
>      uint8_t *img_ptr;
>      int index, x, y;
> -
>      for (index = 0; index < image->numcomps; index++) {
> +        int plane = index?index-1:image->numcomps-1;
>

Won't this break things for other pictures (e.g., RGB, YUV, etc.)?

         comp_data = image->comps[index].data;
>          for (y = 0; y < image->comps[index].h; y++) {
> -            img_ptr = picture->data[index] + y * picture->linesize[index];
> +            img_ptr = picture->data[plane] + y * picture->linesize[plane];
>              for (x = 0; x < image->comps[index].w; x++) {
>                  *img_ptr = 0x80 * image->comps[index].sgnd + *comp_data;
>                  img_ptr++;
> @@ -408,6 +408,23 @@ static int libopenjpeg_decode_frame(AVCodecContext
> *avctx,
>      if (avctx->pix_fmt == AV_PIX_FMT_NONE)
>          avctx->pix_fmt = libopenjpeg_guess_pix_fmt(image);
>
> +    if (avctx->pix_fmt == AV_PIX_FMT_NONE) {
> +        if (image->numcomps == 4 &&
> +            image->comps[0].dx == 1 && image->comps[0].dy == 1 &&
> +            image->comps[1].dx == 1 && image->comps[1].dy == 1 &&
> +            image->comps[2].dx == image->comps[3].dx &&
> +            image->comps[2].dy == image->comps[3].dy) {
> +            int maxprec = 0;
> +            for (int i = 0; i < 4; i++)
> +                maxprec = FFMAX(maxprec, image->comps[i].prec);
> +            if (maxprec == 8 &&
> +                image->comps[2].dx == 2 &&
> +                image->comps[2].dy == 2) {
> +                    avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
> +            }
> +        }
> +    }
> +
>

Please move this up to libopenjpeg_guess_pix_fmt.

Also, are the planes stored in this image stored in AYUV order?