2017-05-02 16:21 GMT+02:00 Nicolas George <geo...@nsup.org>:
> Le tridi 13 floréal, an CCXXV, Carl Eugen Hoyos a écrit :
>> Attached patch allows reading the aspect ratio from jpeg2000 files.
>> Kakadu allows to produce samples, the "aspect" is defined as the
>> horizontal and vertical resolution as in tiff.
>
> Did you test what happens with this patch if you try to read two frames
> with the same context (for example with the image2 demuxer), the first
> frame has a non-square-pixels resolution defined and the second has no
> resolution indication at all?
>
> The correct result would be to have a sample aspect ratio on the first
> frame and not on the second.
>
> But with this code, since the first resolution is stored in the context
> and never cleared, it looks like it will be kept for the remaining
> images.
New, fixed patch attached.
(There also was another bug.)
Thank you, Carl Eugen
From 027d46030354c99ce496d299ff3c95e739ecdda2 Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <ceho...@ag.or.at>
Date: Tue, 2 May 2017 16:27:47 +0200
Subject: [PATCH] lavc/jpeg2000dec: Read the sample aspect ratio from the jp2
resolution box.
---
libavcodec/jpeg2000dec.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index e9f5f51..17ca257 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -26,6 +26,7 @@
*/
#include <inttypes.h>
+#include <math.h>
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
@@ -106,6 +107,7 @@ typedef struct Jpeg2000DecoderContext {
int tile_width, tile_height;
unsigned numXtiles, numYtiles;
int maxtilelen;
+ AVRational sar;
Jpeg2000CodingStyle codsty[4];
Jpeg2000QuantStyle qntsty[4];
@@ -1982,6 +1984,7 @@ static int jp2_find_codestream(Jpeg2000DecoderContext *s)
atom2_end = bytestream2_tell(&s->g) + atom2_size - 8;
if (atom2_size < 8 || atom2_end > atom_end || atom2_end < atom2_size)
break;
+ atom2_size -= 8;
if (atom2 == JP2_CODESTREAM) {
return 1;
} else if (atom2 == MKBETAG('c','o','l','r') && atom2_size >= 7) {
@@ -2043,6 +2046,34 @@ static int jp2_find_codestream(Jpeg2000DecoderContext *s)
if (cn < 4 && asoc < 4)
s->cdef[cn] = asoc;
}
+ } else if (atom2 == MKBETAG('r','e','s',' ') && atom2_size >= 18) {
+ int64_t vnum, vden, hnum, hden, vexp, hexp;
+ uint32_t resx;
+ bytestream2_skip(&s->g, 4);
+ resx = bytestream2_get_be32u(&s->g);
+ if (resx != MKBETAG('r','e','s','c') && resx != MKBETAG('r','e','s','d')) {
+ bytestream2_seek(&s->g, atom2_end, SEEK_SET);
+ continue;
+ }
+ vnum = bytestream2_get_be16u(&s->g);
+ vden = bytestream2_get_be16u(&s->g);
+ hnum = bytestream2_get_be16u(&s->g);
+ hden = bytestream2_get_be16u(&s->g);
+ vexp = bytestream2_get_byteu(&s->g);
+ hexp = bytestream2_get_byteu(&s->g);
+ if (vexp > hexp) {
+ vexp -= hexp;
+ hexp = 0;
+ } else {
+ hexp -= vexp;
+ vexp = 0;
+ }
+ if ( INT64_MAX / (hnum * vden) > pow(10, hexp)
+ && INT64_MAX / (vnum * hden) > pow(10, vexp))
+ av_reduce(&s->sar.den, &s->sar.num,
+ hnum * vden * pow(10, hexp),
+ vnum * hden * pow(10, vexp),
+ INT32_MAX);
}
bytestream2_seek(&s->g, atom2_end, SEEK_SET);
} while (atom_end - atom2_end >= 8);
@@ -2125,6 +2156,9 @@ static int jpeg2000_decode_frame(AVCodecContext *avctx, void *data,
if (s->avctx->pix_fmt == AV_PIX_FMT_PAL8)
memcpy(picture->data[1], s->palette, 256 * sizeof(uint32_t));
+ if (s->sar.num && s->sar.den)
+ avctx->sample_aspect_ratio = s->sar;
+ s->sar.num = s->sar.den = 0;
return bytestream2_tell(&s->g);
--
1.7.10.4
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