On 9/4/2021 12:28 PM, Michael Niedermayer wrote:
On Fri, Sep 03, 2021 at 03:45:55PM -0300, James Almer wrote:
On 9/3/2021 3:39 PM, Michael Niedermayer wrote:
Fixes: Timeout (56sec -> 15sec)
Fixes:
37141/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-6192122867875840
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavcodec/mpegutils.c | 56 ++++++++++++++++++++++++------------------
1 file changed, 32 insertions(+), 24 deletions(-)
diff --git a/libavcodec/mpegutils.c b/libavcodec/mpegutils.c
index e5105ecc58..e91c554781 100644
--- a/libavcodec/mpegutils.c
+++ b/libavcodec/mpegutils.c
@@ -187,7 +187,6 @@ void ff_print_debug_info2(AVCodecContext *avctx, AVFrame
*pict, uint8_t *mbskip_
av_freep(&mvs);
}
-
Stray change.
/* TODO: export all the following to make them accessible for users (and
filters) */
if (avctx->hwaccel || !mbtype_table)
return;
@@ -195,71 +194,80 @@ void ff_print_debug_info2(AVCodecContext *avctx, AVFrame
*pict, uint8_t *mbskip_
if (avctx->debug & (FF_DEBUG_SKIP | FF_DEBUG_QP | FF_DEBUG_MB_TYPE)) {
int x,y;
+#define MB_STRING_SIZE 6
+ char *mbstring = av_malloc(MB_STRING_SIZE * mb_width + 1);
+ if (!mbstring)
+ return;
av_log(avctx, AV_LOG_DEBUG, "New frame, type: %c\n",
av_get_picture_type_char(pict->pict_type));
for (y = 0; y < mb_height; y++) {
+ char *mbs = mbstring;
for (x = 0; x < mb_width; x++) {
+ av_assert0(mbs - mbstring <= MB_STRING_SIZE * x);
if (avctx->debug & FF_DEBUG_SKIP) {
int count = mbskip_table ? mbskip_table[x + y *
mb_stride] : 0;
if (count > 9)
count = 9;
- av_log(avctx, AV_LOG_DEBUG, "%1d", count);
+ *mbs++ = '0' + count;
This is ugly and not very obvious at first glance. Can you use lavu's bprint
or something like that instead?
the whole point of the patch is to eliminate the string formating overhead.
(which surprisingly is significant)
so as long as we have a "%d" style format in there, it at least feels like we
arent doing a good job at eliminating it
Is the string formatting the problem, or the constant calls to av_log()?
av_bprintf() would do the string formatting, but append each character
into a buffer you can then use to call av_log() once at the end.
Something like
av_bprint_init(&bp, MB_STRING_SIZE * mb_width + 1, UINT_MAX);
[...]
av_bprintf(&bp, "%1d", count);
av_bprint_chars(&bp, 'P', 1);
[...]
av_bprint_finalize(&bp, &buf);
av_log(avctx, AV_LOG_DEBUG, "%s\n" buf);
av_free(buf);
would moving this in a seperate function resolve this concern too ?
If the above doesn't perform well (Or you don't feel like trying it),
then an inline function or macro should be fine.
thx
[...]
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