| Message ID | 20190727223122.28243-1-michael@niedermayer.cc |
|---|---|
| State | Superseded |
| Headers | show |
On 28.07.2019, at 00:31, Michael Niedermayer <michael@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 <michael@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...
On Sun, Jul 28, 2019 at 12:45:36AM +0200, Reimar Döffinger wrote: > > > On 28.07.2019, at 00:31, Michael Niedermayer <michael@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 <michael@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... will fix and retest while ensuring this code is actually tested thanks [...]
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; } y_out -= frame->linesize[0]; u_out -= frame->linesize[1];
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 <michael@niedermayer.cc> --- libavcodec/lcldec.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)