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 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I do not agree with what you have to say, but I'll defend to the death your right to say it. -- Voltaire
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