On Wed, Oct 24, 2018 at 5:09 PM Hendrik Leppkes <h.lepp...@gmail.com> wrote:
>
> On Wed, Oct 24, 2018 at 5:06 PM Jun Zhao <mypopy...@gmail.com> wrote:
> >
> > From: Jun Zhao <jun.z...@intel.com>
> >
> > Add checking to avoid calling ff_thread_get_format repeatedly
> > whenever new slice header decoded.
> >
> > Signed-off-by: Lin Xie <lin....@intel.com>
> > Signed-off-by: Jun Zhao <jun.z...@intel.com>
> > ---
> > libavcodec/hevcdec.c | 17 +++++++++++------
> > 1 files changed, 11 insertions(+), 6 deletions(-)
> >
> > diff --git a/libavcodec/hevcdec.c b/libavcodec/hevcdec.c
> > index a3b5c8c..16032a5 100644
> > --- a/libavcodec/hevcdec.c
> > +++ b/libavcodec/hevcdec.c
> > @@ -317,7 +317,6 @@ static void export_stream_params(AVCodecContext *avctx,
> > const HEVCParamSets *ps,
> > const HEVCWindow *ow = &sps->output_window;
> > unsigned int num = 0, den = 0;
> >
> > - avctx->pix_fmt = sps->pix_fmt;
> > avctx->coded_width = sps->width;
> > avctx->coded_height = sps->height;
> > avctx->width = sps->width - ow->left_offset -
> > ow->right_offset;
> > @@ -357,7 +356,7 @@ static void export_stream_params(AVCodecContext *avctx,
> > const HEVCParamSets *ps,
> > num, den, 1 << 30);
> > }
> >
> > -static enum AVPixelFormat get_format(HEVCContext *s, const HEVCSPS *sps)
> > +static enum AVPixelFormat get_format(HEVCContext *s, const HEVCSPS *sps,
> > int force_callback)
> > {
> > #define HWACCEL_MAX (CONFIG_HEVC_DXVA2_HWACCEL + \
> > CONFIG_HEVC_D3D11VA_HWACCEL * 2 + \
> > @@ -366,6 +365,8 @@ static enum AVPixelFormat get_format(HEVCContext *s,
> > const HEVCSPS *sps)
> > CONFIG_HEVC_VIDEOTOOLBOX_HWACCEL + \
> > CONFIG_HEVC_VDPAU_HWACCEL)
> > enum AVPixelFormat pix_fmts[HWACCEL_MAX + 2], *fmt = pix_fmts;
> > + const enum AVPixelFormat *choices = pix_fmts;
> > + int i;
> >
> > switch (sps->pix_fmt) {
> > case AV_PIX_FMT_YUV420P:
> > @@ -418,6 +419,11 @@ static enum AVPixelFormat get_format(HEVCContext *s,
> > const HEVCSPS *sps)
> > *fmt++ = sps->pix_fmt;
> > *fmt = AV_PIX_FMT_NONE;
> >
> > + if (!force_callback)
> > + for (i = 0; choices[i] != AV_PIX_FMT_NONE; i++)
> > + if (choices[i] == s->avctx->pix_fmt)
> > + return choices[i];
> > +
Additionally, there can be a lot more properties that might result in
a different hwaccel selection, or even software fallback. Resolution,
frame rate, who knows what else.
The point of get_format is not only to determine the frame format, but
also notify the usercode / hwaccel about any changes in stream
properties.
If too many calls to get_format cause serious issues, then typically
the usercode that implements get_format is written badly. It should
verify that the current hwaccel is still capable of decoding the new
format, and only then act, instead of always re-creating the hardware
decoder. I realize that our avcodec code is also guilty of that, but
I've complained about that before, and thats the prime reason I also
don't use it. :)
- Hendrik
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