[FFmpeg-cvslog] snow: remove an obsolete av_assert2

[Andreas Cadhalpun]

ffmpeg | branch: release/2.6 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Thu Jul  9 19:50:34 2015 +0200| [2d89356641f89cad9dc4ee961fa1cecf1e0f548e] | committer: Michael Niedermayer

snow: remove an obsolete av_assert2

It asserts that the frame linesize is larger than 37, but it can be
smaller and decoding such frames works.

Before commit cc884a35 src_stride > 7*MB_SIZE was necessary, because the
blocks were interleaved in the tmp buffer and the last block was added
with an offset of 6*MB_SIZE.
It was changed for src_stride <= 7*MB_SIZE to write the blocks
sequentially, hence the larger tmp_step.
After that the assert was only necessary to make sure that the buffer
remained large enough.
Since commit bd2b6b33 s->scratchbuf is used as tmp buffer.
As part of commit 86e107a7 the minimal scratchbuf size was increased to
256*7*MB_SIZE, which is enough for any src_stride <= 7*MB_SIZE.

Also add a comment explaining the tmp_step calculation.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 3526a120f92929cb0a4009e403ee2f141030c487)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 26cb351452e76dc4a61028f277cf11b8d7abd74b)

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2d89356641f89cad9dc4ee961fa1cecf1e0f548e
---

 libavcodec/snow.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/snow.h b/libavcodec/snow.h
index f5cbae3..6dbcaf3 100644
--- a/libavcodec/snow.h
+++ b/libavcodec/snow.h
@@ -303,6 +303,8 @@ static av_always_inline void add_yblock(SnowContext *s, int sliced, slice_buffer
     BlockNode *lb= lt+b_stride;
     BlockNode *rb= lb+1;
     uint8_t *block[4];
+    // When src_stride is large enough, it is possible to interleave the blocks.
+    // Otherwise the blocks are written sequentially in the tmp buffer.
     int tmp_step= src_stride >= 7*MB_SIZE ? MB_SIZE : MB_SIZE*src_stride;
     uint8_t *tmp = s->scratchbuf;
     uint8_t *ptmp;
@@ -346,8 +348,6 @@ static av_always_inline void add_yblock(SnowContext *s, int sliced, slice_buffer
 
     if(b_w<=0 || b_h<=0) return;
 
-    av_assert2(src_stride > 2*MB_SIZE + 5);
-
     if(!sliced && offset_dst)
         dst += src_x + src_y*dst_stride;
     dst8+= src_x + src_y*src_stride;