[vlc-devel] [PATCH] vpx: encode: fix alignment to avoid copying line by line

Thomas Guillem thomas at gllm.fr
Thu Mar 29 09:30:31 CEST 2018



On Wed, Mar 28, 2018, at 20:29, Tristan Matthews wrote:
> On Tue, Mar 20, 2018 at 8:38 PM, Tristan Matthews <tmatth at videolan.org> wrote:
> > This is based on a suggestion by Fran├žois for the aom encoder.
> >
> > ---
> >  modules/codec/vpx.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> >
> > diff --git a/modules/codec/vpx.c b/modules/codec/vpx.c
> > index 76331a714b..fdd75ba256 100644
> > --- a/modules/codec/vpx.c
> > +++ b/modules/codec/vpx.c
> > @@ -441,23 +441,22 @@ static block_t *Encode(encoder_t *p_enc, picture_t *p_pict)
> >      unsigned i_h = p_enc->fmt_in.video.i_visible_height;
> >
> >      /* Create and initialize the vpx_image */
> > -    if (!vpx_img_alloc(&img, VPX_IMG_FMT_I420, i_w, i_h, 1)) {
> > +    if (!vpx_img_alloc(&img, VPX_IMG_FMT_I420, i_w, i_h, 32)) {
> >          VPX_ERR(p_enc, ctx, "Failed to allocate image");
> >          return NULL;
> >      }
> >      for (int plane = 0; plane < p_pict->i_planes; plane++) {
> >          uint8_t *src = p_pict->p[plane].p_pixels;
> >          uint8_t *dst = img.planes[plane];
> > -        int src_stride = p_pict->p[plane].i_pitch;
> >          int dst_stride = img.stride[plane];
> >
> > -        int size = __MIN(src_stride, dst_stride);
> > -        for (int line = 0; line < p_pict->p[plane].i_visible_lines; line++)
> > -        {
> > -            memcpy(dst, src, size);
> > -            src += src_stride;
> > -            dst += dst_stride;
> > +        if (unlikely(dst_stride != p_pict->p[plane].i_pitch)) {
> > +            VPX_ERR(p_enc, ctx, "Unexpected stride mismatch");
> > +            vpx_img_free(&img);

I think that this case could happen, maybe you should foreach (lines) { memcpy() } here, no ?

> > +            return NULL;
> >          }
> > +
> > +        memcpy(dst, src, dst_stride*p_pict->p[plane].i_visible_lines);
> >      }
> >
> >      int flags = 0;
> > --
> > 2.16.2
> >
> 
> Thomas, any thoughts on this? I see that you've been using vpx
> encoding as a fallback for chromecast.
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