[FFmpeg-cvslog] avcodec/utvideodec: Move bitstream end check out of inner loop

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Tue Jun 27 21:47:31 2017 +0200| [1835c5e7a4fd3a1e7c8a51ed410cecbfe6804ade] | committer: Michael Niedermayer

avcodec/utvideodec: Move bitstream end check out of inner loop

This is not needed when the buffer is large enough for the worst case of a line

2% faster vlc reading

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1835c5e7a4fd3a1e7c8a51ed410cecbfe6804ade
---

 libavcodec/utvideodec.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/libavcodec/utvideodec.c b/libavcodec/utvideodec.c
index 44841aaa65..815b71cfb6 100644
--- a/libavcodec/utvideodec.c
+++ b/libavcodec/utvideodec.c
@@ -196,11 +196,6 @@ static int decode_plane10(UtvideoContext *c, int plane_no,
         prev = 0x200;
         for (j = sstart; j < send; j++) {
             for (i = 0; i < width * step; i += step) {
-                if (get_bits_left(&gb) <= 0) {
-                    av_log(c->avctx, AV_LOG_ERROR,
-                           "Slice decoding ran out of bits\n");
-                    goto fail;
-                }
                 pix = get_vlc2(&gb, vlc.table, vlc.bits, 3);
                 if (pix < 0) {
                     av_log(c->avctx, AV_LOG_ERROR, "Decoding error\n");
@@ -214,6 +209,11 @@ static int decode_plane10(UtvideoContext *c, int plane_no,
                 dest[i] = pix;
             }
             dest += stride;
+            if (get_bits_left(&gb) < 0) {
+                av_log(c->avctx, AV_LOG_ERROR,
+                        "Slice decoding ran out of bits\n");
+                goto fail;
+            }
         }
         if (get_bits_left(&gb) > 32)
             av_log(c->avctx, AV_LOG_WARNING,
@@ -302,11 +302,6 @@ static int decode_plane(UtvideoContext *c, int plane_no,
         prev = 0x80;
         for (j = sstart; j < send; j++) {
             for (i = 0; i < width * step; i += step) {
-                if (get_bits_left(&gb) <= 0) {
-                    av_log(c->avctx, AV_LOG_ERROR,
-                           "Slice decoding ran out of bits\n");
-                    goto fail;
-                }
                 pix = get_vlc2(&gb, vlc.table, vlc.bits, 3);
                 if (pix < 0) {
                     av_log(c->avctx, AV_LOG_ERROR, "Decoding error\n");
@@ -318,6 +313,11 @@ static int decode_plane(UtvideoContext *c, int plane_no,
                 }
                 dest[i] = pix;
             }
+            if (get_bits_left(&gb) < 0) {
+                av_log(c->avctx, AV_LOG_ERROR,
+                        "Slice decoding ran out of bits\n");
+                goto fail;
+            }
             dest += stride;
         }
         if (get_bits_left(&gb) > 32)
@@ -610,6 +610,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
 
     c->frame_pred = (c->frame_info >> 8) & 3;
 
+    max_slice_size += 4*avctx->width;
+
     av_fast_malloc(&c->slice_bits, &c->slice_bits_size,
                    max_slice_size + AV_INPUT_BUFFER_PADDING_SIZE);