On Fri, Mar 24, 2023 at 01:08:56AM +0100, Michael Niedermayer wrote:
> On Thu, Mar 23, 2023 at 08:32:48AM -0300, James Almer wrote:
> > On 3/23/2023 6:50 AM, Michael Niedermayer wrote:
> > > On Mon, Mar 20, 2023 at 07:07:59PM -0300, James Almer wrote:
> > > > On 3/19/2023 4:42 PM, Michael Niedermayer wrote:
> > > > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > > > ---
> > > > >    libavcodec/snowenc.c | 10 +++++++++-
> > > > >    1 file changed, 9 insertions(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/libavcodec/snowenc.c b/libavcodec/snowenc.c
> > > > > index 658684c575..5fb5906ed8 100644
> > > > > --- a/libavcodec/snowenc.c
> > > > > +++ b/libavcodec/snowenc.c
> > > > > @@ -26,6 +26,7 @@
> > > > >    #include "avcodec.h"
> > > > >    #include "codec_internal.h"
> > > > >    #include "encode.h"
> > > > > +#include "internal.h" //For AVCodecInternal.recon_frame
> > > > >    #include "me_cmp.h"
> > > > >    #include "packet_internal.h"
> > > > >    #include "snow_dwt.h"
> > > > > @@ -1576,6 +1577,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
> > > > >    {
> > > > >        SnowContext *s = avctx->priv_data;
> > > > >        RangeCoder * const c= &s->c;
> > > > > +    AVCodecInternal *avci = avctx->internal;
> > > > >        AVFrame *pic;
> > > > >        const int width= s->avctx->width;
> > > > >        const int height= s->avctx->height;
> > > > > @@ -1877,6 +1879,10 @@ redo_frame:
> > > > >                                       s->encoding_error,
> > > > >                                       (s->avctx->flags&AV_CODEC_FLAG_PSNR) ? SNOW_MAX_PLANES : 0,
> > > > >                                       s->current_picture->pict_type);
> > > > > +    if (s->avctx->flags & AV_CODEC_FLAG_RECON_FRAME) {
> > > > > +        av_frame_unref(avci->recon_frame);
> > > > > +        av_frame_ref(avci->recon_frame, s->current_picture);
> > > > > +    }
> > > > >        pkt->size = ff_rac_terminate(c, 0);
> > > > >        if (s->current_picture->key_frame)
> > > > > @@ -1934,7 +1940,9 @@ const FFCodec ff_snow_encoder = {
> > > > >        CODEC_LONG_NAME("Snow"),
> > > > >        .p.type         = AVMEDIA_TYPE_VIDEO,
> > > > >        .p.id           = AV_CODEC_ID_SNOW,
> > > > > -    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
> > > > > +    .p.capabilities = AV_CODEC_CAP_DR1 |
> > > > > +                      AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE |
> > > > > +                      AV_CODEC_CAP_ENCODER_RECON_FRAME,
> > > > >        .priv_data_size = sizeof(SnowContext),
> > > > >        .init           = encode_init,
> > > > >        FF_CODEC_ENCODE_CB(encode_frame),
> > > > 
> > > > Testing with the tool from https://git.khirnov.net/libav.git/commit/?h=recon&id=d78e17840347abfe10b2bc7e789c60665de56e1f
> > > > (Which i hope will be upstreamed eventually) i get
> > > > 
> > > > $ tools/enc_recon_frame_test input.y4m snow flags=+bitexact 10
> > > > Checksum mismatch in frame ts=0, plane 0
> > > 
> > > I cannot replicate this, using matrixbench and above command line i get no
> > > mismatches, where can i find the input.y4m you used ?
> > 
> > It was https://0x0.st/sfRh.y4m
> > 
> > > 
> > > also would be nice if this tool would write a image showing the difference
> > > 
> > > thx
> > > 
> > > > 
> > > > I don't know if this really matters for snow (is it mean to be bitexact?),
> > > > but it seems the very first frame returned by the reconstructed frame API is
> > > > not the same as the one output by the snow decoder. The rest seem to match,
> > > > though.
> > > 
> > > This sounds rather strange, the first frame would be used as reference for
> > > motion compensation so the subsequent frames matching after a mismatch is
> > > "surprising"
> > 
> > I tried other supported encoders like libx264 and librav1e and none of them
> > report mismatches.
> 
> bugs
> ill send a patchset

will apply the fix as well as these 3 patches here


[...]

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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
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