On Sun, Jul 28, 2019 at 12:45:36AM +0200, Reimar Döffinger wrote: > > > On 28.07.2019, at 00:31, Michael Niedermayer <mich...@niedermayer.cc> wrote: > > > This merges several byte operations and avoids some shifts inside the loop > > > > Improves: Timeout (330sec -> 134sec) > > Improves: > > 15599/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSZH_fuzzer-5658127116009472 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > --- > > libavcodec/lcldec.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/libavcodec/lcldec.c b/libavcodec/lcldec.c > > index 104defa5f5..c3787b3cbe 100644 > > --- a/libavcodec/lcldec.c > > +++ b/libavcodec/lcldec.c > > @@ -391,13 +391,13 @@ static int decode_frame(AVCodecContext *avctx, void > > *data, int *got_frame, AVPac > > break; > > case IMGTYPE_YUV422: > > for (row = 0; row < height; row++) { > > - for (col = 0; col < width - 3; col += 4) { > > + for (col = 0; col < (width - 2)>>1; col += 2) { > > memcpy(y_out + col, encoded, 4); > > encoded += 4; > > - u_out[ col >> 1 ] = *encoded++ + 128; > > - u_out[(col >> 1) + 1] = *encoded++ + 128; > > - v_out[ col >> 1 ] = *encoded++ + 128; > > - v_out[(col >> 1) + 1] = *encoded++ + 128; > > + AV_WN16(u_out + col, AV_RN16(encoded) ^ 0x8080); > > + encoded += 2; > > + AV_WN16(v_out + col, AV_RN16(encoded) ^ 0x8080); > > + encoded += 2; > > Huh? Surely the pixel stride used for y_out still needs to be double of the > u/v one?
> I suspect doing only the AV_RN16/xor optimization might be best, the one
> shift saved seems not worth the risk/complexity...
if you want i can remove the shift change ?
with the fixed shift change its 155sec, if i remove the shift optimization its
170sec
patch for the 155 case below:
commit 56998b7d57a2cd0ed7f53981c50e76fd419cd86f (HEAD)
Author: Michael Niedermayer <mich...@niedermayer.cc>
Date: Sat Jul 27 22:46:34 2019 +0200
avcodec/lcldec: Optimize YUV422 case
This merges several byte operations and avoids some shifts inside the loop
Improves: Timeout (330sec -> 155sec)
Improves:
15599/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSZH_fuzzer-5658127116009472
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
diff --git a/libavcodec/lcldec.c b/libavcodec/lcldec.c
index 104defa5f5..9e018ff5a9 100644
--- a/libavcodec/lcldec.c
+++ b/libavcodec/lcldec.c
@@ -391,13 +391,13 @@ static int decode_frame(AVCodecContext *avctx, void
*data, int *got_frame, AVPac
break;
case IMGTYPE_YUV422:
for (row = 0; row < height; row++) {
- for (col = 0; col < width - 3; col += 4) {
- memcpy(y_out + col, encoded, 4);
+ for (col = 0; col < (width - 2)>>1; col += 2) {
+ memcpy(y_out + 2 * col, encoded, 4);
encoded += 4;
- u_out[ col >> 1 ] = *encoded++ + 128;
- u_out[(col >> 1) + 1] = *encoded++ + 128;
- v_out[ col >> 1 ] = *encoded++ + 128;
- v_out[(col >> 1) + 1] = *encoded++ + 128;
+ AV_WN16(u_out + col, AV_RN16(encoded) ^ 0x8080);
+ encoded += 2;
+ AV_WN16(v_out + col, AV_RN16(encoded) ^ 0x8080);
+ encoded += 2;
}
y_out -= frame->linesize[0];
u_out -= frame->linesize[1];
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Many that live deserve death. And some that die deserve life. Can you give
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even the very wise cannot see all ends. -- Gandalf
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