When an empty annex B NAL unit (i.e. 0x000001 immediately followed by a
three or four-byte start code) is encountered during annex B->mp4
conversion, a NAL unit of size zero is created; this is invalid.
Furthermore, several functions simply presumed all NAL units to be
nonempty and treated the first byte as the NAL unit type.
Ticket #7200 contains a sample with such NAL units.
This commit skips empty NAL units during annex B->mp4 conversion,
ensuring that the callers don't need to check for themselves.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
libavformat/avc.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/libavformat/avc.c b/libavformat/avc.c
index 98462940ad..17fcd1e73f 100644
--- a/libavformat/avc.c
+++ b/libavformat/avc.c
@@ -104,6 +104,7 @@ const uint8_t *ff_avc_parse_nalu(const uint8_t **start,
const uint8_t **nal_end,
p += 3;
}
+search_again:
next = avc_find_startcode_internal(p, end);
if (next) {
@@ -112,6 +113,12 @@ const uint8_t *ff_avc_parse_nalu(const uint8_t **start,
const uint8_t **nal_end,
} else {
*nal_end = end;
}
+ if (*nal_end == p) {
+ if (!next)
+ return NULL;
+ p = next;
+ goto search_again;
+ }
*start = next;
return p;
}
--
2.20.1
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