On Fri, Sep 02, 2016 at 04:49:54PM -0700, Jonathan Campbell wrote: > > On 09/02/2016 04:37 PM, Michael Niedermayer wrote: > >On Fri, Sep 02, 2016 at 04:05:44PM -0700, Jonathan Campbell wrote: > >>On 09/02/2016 01:56 PM, Michael Niedermayer wrote: > >>>On Fri, Sep 02, 2016 at 01:13:33PM -0700, Jonathan Campbell wrote: > >>>>On 09/02/2016 01:01 PM, Michael Niedermayer wrote: > >>>>>On Fri, Sep 02, 2016 at 10:19:23AM -0700, Jonathan Campbell wrote: > >>>>>[...] > >>>>>>CRC computation isn't fast enough? What should I use then? A sum of > >>>>>>byte values? > >>>>>av_lfg_init() calls av_md5_sum() > >>>>>av_md5_sum() is too slow to be called per ac3 frame > >>>>> > >>>>>[...] > >>>>> > >>>>> > >>>>>_______________________________________________ > >>>>>ffmpeg-devel mailing list > >>>>>ffmpeg-devel@ffmpeg.org > >>>>>http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > >>>>Then for this to work at better performance, I'm going to have to > >>>>either directly modify the AVLFG struct state (probably not a good > >>>>idea), or add a function to libavutil/lfg.c that allows "fast > >>>>seeding" without the use of MD5 which could probably be something as > >>>>simple as copy the 32-bit seed 16 times through c->state[] with or > >>>>without modification during the loop. Sound good? > >>>yes, something like this > >>>probably spliting the input into 16 parts get 16 CRCs and use them > >>>instead of replication is probably better > >>> > >>> > >>>[...] > >>> > >>> > >>>_______________________________________________ > >>>ffmpeg-devel mailing list > >>>ffmpeg-devel@ffmpeg.org > >>>http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > >>How's this: > >> > >>void av_lfg_init_from_data(AVLFG *c, const unsigned char *data, > >>unsigned int length) { > >> unsigned int beg, end, segm; > >> const AVCRC *avcrc; > >> uint32_t crc = 0; > >1 might be better > > > >should be ok otherwise didnt review it deeply though > > > >[...] > > > > > >_______________________________________________ > >ffmpeg-devel mailing list > >ffmpeg-devel@ffmpeg.org > >http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > Finished patch. Hopefully it won't get garbled as an attachment. > > Jonathan Campbell >
> libavcodec/ac3dec.c | 7 +++++++ > libavcodec/ac3dec.h | 4 ++++ > libavcodec/ac3dec_fixed.c | 1 + > libavcodec/ac3dec_float.c | 1 + > libavutil/lfg.c | 27 +++++++++++++++++++++++++++ > libavutil/lfg.h | 5 +++++ should be in a different patch also needs minor version bump and APIChanges update also please generate patches with git format-patch or git send-email see the respective man pages (otherwise they woul be lacking commit messages) thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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