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

[gautamramk at gmail.com]

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;
         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;
+            }
+        }
+    }
+
     if (avctx->pix_fmt == AV_PIX_FMT_NONE) {
         av_log(avctx, AV_LOG_ERROR, "Unable to determine pixel format.\n");
         ret = AVERROR_UNKNOWN;
-- 
2.17.1