That have unused symbols coded in DHT.
Signed-off-by: Paul B Mahol <one...@gmail.com>
---
libavcodec/jpegtables.c | 15 ++-------------
libavcodec/mjpegdec.c | 41 +++++++++++++++++++++++++++++------------
2 files changed, 31 insertions(+), 25 deletions(-)
diff --git a/libavcodec/jpegtables.c b/libavcodec/jpegtables.c
index fa5c6f9fc5..e44bc7a22a 100644
--- a/libavcodec/jpegtables.c
+++ b/libavcodec/jpegtables.c
@@ -130,25 +130,14 @@ void ff_mjpeg_build_huffman_codes(uint8_t *huff_size,
uint16_t *huff_code,
{
int i, j, k,nb, code, sym;
- /* Some badly encoded files [1] map 2 different codes to symbol 0.
- Only the first one is valid, so we zero-initialize this here and
- make sure we only set it once (the first time) in the loop below.
-
- [1]: Embedded JPEGs in "X7 RAW" and "X7 CinemaDNG" samples here:
- https://www.dji.com/gr/zenmuse-x7/info#downloads
- */
- huff_size[0] = 0;
-
k = 0;
code = 0;
for(i=1;i<=16;i++) {
nb = bits_table[i];
for(j=0;j<nb;j++) {
sym = val_table[k++];
- if (sym != 0 || huff_size[sym] == 0) { /* see comment above */
- huff_size[sym] = i;
- huff_code[sym] = code;
- }
+ huff_size[sym] = i;
+ huff_code[sym] = code;
code++;
}
code <<= 1;
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index e7a4e08c1c..d4286684df 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -50,6 +50,25 @@
#include "bytestream.h"
+static void build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code,
+ const uint8_t *bits_table)
+{
+ int i, j, k,nb, code;
+
+ k = 0;
+ code = 0;
+ for(i=1;i<=16;i++) {
+ nb = bits_table[i];
+ for(j=0;j<nb;j++) {
+ huff_size[k] = i;
+ huff_code[k] = code;
+ code++;
+ k++;
+ }
+ code <<= 1;
+ }
+}
+
static int build_vlc(VLC *vlc, const uint8_t *bits_table,
const uint8_t *val_table, int nb_codes,
int use_static, int is_ac)
@@ -61,13 +80,14 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table,
av_assert0(nb_codes <= 256);
- ff_mjpeg_build_huffman_codes(huff_size, huff_code, bits_table, val_table);
+ build_huffman_codes(huff_size, huff_code, bits_table);
- for (i = 0; i < 256; i++)
- huff_sym[i] = i + 16 * is_ac;
+ for (i = 0; i < 256; i++) {
+ huff_sym[i] = val_table[i] + 16 * is_ac;
- if (is_ac)
- huff_sym[0] = 16 * 256;
+ if (is_ac && !val_table[i])
+ huff_sym[i] = 16 * 256;
+ }
return ff_init_vlc_sparse(vlc, 9, nb_codes, huff_size, 1, 1,
huff_code, 2, 2, huff_sym, 2, 2, use_static);
@@ -240,7 +260,7 @@ int ff_mjpeg_decode_dqt(MJpegDecodeContext *s)
/* decode huffman tables and build VLC decoders */
int ff_mjpeg_decode_dht(MJpegDecodeContext *s)
{
- int len, index, i, class, n, v, code_max;
+ int len, index, i, class, n, v;
uint8_t bits_table[17];
uint8_t val_table[256];
int ret = 0;
@@ -270,11 +290,8 @@ int ff_mjpeg_decode_dht(MJpegDecodeContext *s)
if (len < n || n > 256)
return AVERROR_INVALIDDATA;
- code_max = 0;
for (i = 0; i < n; i++) {
v = get_bits(&s->gb, 8);
- if (v > code_max)
- code_max = v;
val_table[i] = v;
}
len -= n;
@@ -282,15 +299,15 @@ int ff_mjpeg_decode_dht(MJpegDecodeContext *s)
/* build VLC and flush previous vlc if present */
ff_free_vlc(&s->vlcs[class][index]);
av_log(s->avctx, AV_LOG_DEBUG, "class=%d index=%d nb_codes=%d\n",
- class, index, code_max + 1);
+ class, index, n + 1);
if ((ret = build_vlc(&s->vlcs[class][index], bits_table, val_table,
- code_max + 1, 0, class > 0)) < 0)
+ n + 1, 0, class > 0)) < 0)
return ret;
if (class > 0) {
ff_free_vlc(&s->vlcs[2][index]);
if ((ret = build_vlc(&s->vlcs[2][index], bits_table, val_table,
- code_max + 1, 0, 0)) < 0)
+ n + 1, 0, 0)) < 0)
return ret;
}
--
2.17.1
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
