On 28.07.2019, at 13:56, Michael Niedermayer <mich...@niedermayer.cc> wrote:
> 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: I can't decide, it's a little uglier but a little faster... Unless someone else has an opinion, go with whatever you prefer. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".