[FFmpeg-devel] [PATCH v2 12/13] cbs_mpeg2.c: improve readability of start code search (part 2)

Scott Theisen scott.the.elm at gmail.com
Thu Feb 3 20:44:49 EET 2022


If the last four bytes form a valid start code, the loop would run another time.
Since (start == buf_end), start_code is invalidated so the loop terminates.

However, calling avpriv_find_start_code() with p == end, it will immediately
return due to the zero size buffer.  Thus the history is not needed.
---
 libavcodec/cbs_mpeg2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index f2efedde5d..bf95fb7546 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -168,8 +168,9 @@ static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
             // the next unit will be treated as the last unit.
             start_code = 0;
         }
-
-        end = avpriv_find_start_code(start, buf_end, &start_code, 0);
+        else {
+            end = avpriv_find_start_code(start, buf_end, &start_code, 1);
+        }
         start--;
         // decrement so start points to the byte containing the start_code_identifier
         // (may be the last byte of fragment->data); end points to the byte
-- 
2.32.0



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