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-rw-r--r--lib/libv4lconvert/jpeg.c37
1 files changed, 24 insertions, 13 deletions
diff --git a/lib/libv4lconvert/jpeg.c b/lib/libv4lconvert/jpeg.c
index aa9cacec..0142d444 100644
--- a/lib/libv4lconvert/jpeg.c
+++ b/lib/libv4lconvert/jpeg.c
@@ -242,23 +242,34 @@ static int decode_libjpeg_h_samp2(struct v4lconvert_data *data,
y_rows[y] = ydest;
ydest += width;
}
- for (y = 0; y < 8; y++) {
- u_rows[y] = udest;
- v_rows[y] = vdest;
- udest += width / 2;
- vdest += width / 2;
+ /*
+ * For v_samp == 1 were going to get 1 set of uv values per
+ * line, but we need only 1 set per 2 lines since our output
+ * has v_samp == 2. We store every 2 sets in 1 line,
+ * effectively using the second set for each output line.
+ */
+ if (v_samp == 1) {
+ for (y = 0; y < 8; y++) {
+ u_rows[y] = udest;
+ v_rows[y] = vdest;
+ y++;
+ u_rows[y] = udest;
+ v_rows[y] = vdest;
+ udest += width / 2;
+ vdest += width / 2;
+ }
+ } else { /* v_samp == 2 */
+ for (y = 0; y < 8; y++) {
+ u_rows[y] = udest;
+ v_rows[y] = vdest;
+ udest += width / 2;
+ vdest += width / 2;
+ }
}
+
y = jpeg_read_raw_data(cinfo, rows, 8 * v_samp);
if (y != 8 * v_samp)
return -1;
-
- /* For v_samp == 1 were going to get another set of uv values,
- but we need only 1 set since our output has v_samp == 2, so
- rewind u and vdest and overwrite the previous set. */
- if (cinfo->output_scanline % 16) {
- udest -= width * 8 / 2;
- vdest -= width * 8 / 2;
- }
}
return 0;
}

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