From: Matthieu Bouron <matthieu.bou...@stupeflix.com>
---
From random 3264x2448 jpegs, scan data copy on a Nexus5 goes from [15, 28]ms to
[3, 12]ms.
---
libavcodec/mjpegdec.c | 43 +++++++++++++++++++++++++++++++++----------
1 file changed, 33 insertions(+), 10 deletions(-)
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 863738d..9a501d2 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1917,24 +1917,47 @@ int ff_mjpeg_find_marker(MJpegDecodeContext *s,
/* unescape buffer of SOS, use special treatment for JPEG-LS */
if (start_code == SOS && !s->ls) {
const uint8_t *src = *buf_ptr;
+ const uint8_t *ptr = src;
uint8_t *dst = s->buffer;
- while (src < buf_end) {
- uint8_t x = *(src++);
+ #define copy_data_segment(skipped) do { \
+ ssize_t length = (ptr - src) - (skipped); \
+ if (length > 0) { \
+ memcpy(dst, src, length); \
+ dst += length; \
+ src = ptr; \
+ } \
+ } while (0)
+
+ if (s->avctx->codec_id == AV_CODEC_ID_THP) {
+ ptr = buf_end;
+ copy_data_segment(0);
+ } else {
+ while (ptr < buf_end) {
+ uint8_t x = *(ptr++);
- *(dst++) = x;
- if (s->avctx->codec_id != AV_CODEC_ID_THP) {
if (x == 0xff) {
- while (src < buf_end && x == 0xff)
- x = *(src++);
+ ssize_t skipped = -1;
+ while (ptr < buf_end && x == 0xff) {
+ x = *(ptr++);
+ skipped++;
+ }
- if (x >= 0xd0 && x <= 0xd7)
- *(dst++) = x;
- else if (x)
- break;
+ if (skipped > 0)
+ copy_data_segment(skipped);
+
+ if (x < 0xd0 || x > 0xd7) {
+ copy_data_segment(1);
+ if (x)
+ break;
+ }
}
}
+ if (src < ptr)
+ copy_data_segment(0);
}
+ #undef copy_data_segment
+
*unescaped_buf_ptr = s->buffer;
*unescaped_buf_size = dst - s->buffer;
memset(s->buffer + *unescaped_buf_size, 0,
--
2.7.0
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