On 8/8/15, wm4 <nfx...@googlemail.com> wrote: > On Sat, 8 Aug 2015 18:17:37 +0200 > Michael Niedermayer <mich...@niedermayer.cc> wrote: > >> On Sat, Aug 08, 2015 at 05:58:29PM +0200, wm4 wrote: >> > On Sat, 8 Aug 2015 17:14:58 +0200 >> > Michael Niedermayer <michae...@gmx.at> wrote: >> > >> > > From: Michael Niedermayer <mich...@niedermayer.cc> >> > > >> > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> >> > > --- >> > > libswscale/swscale.h | 11 +++++++++++ >> > > libswscale/swscale_internal.h | 11 ----------- >> > > libswscale/version.h | 4 ++-- >> > > 3 files changed, 13 insertions(+), 13 deletions(-) >> > > >> > > diff --git a/libswscale/swscale.h b/libswscale/swscale.h >> > > index 903e120..055c9fc 100644 >> > > --- a/libswscale/swscale.h >> > > +++ b/libswscale/swscale.h >> > > @@ -161,6 +161,17 @@ int sws_isSupportedEndiannessConversion(enum >> > > AVPixelFormat pix_fmt); >> > > struct SwsContext *sws_alloc_context(void); >> > > >> > > /** >> > > + * Allocate and return an SwsContext. >> > > + * This is like sws_getContext() but does not perform the init step, >> > > allowing >> > > + * the user to set additional AVOptions. >> > > + * >> > > + * @see sws_getContext() >> > > + */ >> > > +struct SwsContext *sws_alloc_set_opts(int srcW, int srcH, enum >> > > AVPixelFormat srcFormat, >> > > + int dstW, int dstH, enum >> > > AVPixelFormat dstFormat, >> > > + int flags, const double >> > > *param); >> > > + >> > >> > This looks excessively useless and un-nice to use. >> >> what do you suggest ? >> >> The function is intended to replace: >> >> context = sws_alloc_context() >> if (!context) >> handle error >> >> ret0 = av_opt_set_int(context, "sws_flags", flags, 0); >> ret1 = av_opt_set_int(context, "srcw", srcW, 0); >> ret2 = av_opt_set_int(context, "srch", srcH, 0); >> ret3 = av_opt_set_int(context, "dstw", dstW, 0); >> ret4 = av_opt_set_int(context, "dsth", dstH, 0); >> ret5 = av_opt_set_int(context, "src_format", srcFormat, 0); >> ret6 = av_opt_set_int(context, "dst_format", dstFormat, 0); >> ret7 = av_opt_set(context, "alphablend", "none", 0); > > This does look better to me than a function which has some required > parameters (and at least 1 optional one!), but not all parameters which > are reasonably needed for general pixfmt conversion. Where are the > input and output colorspaces and ranges set? > > The "param" parameter is the worst part if this proposed function. What > does it even mean? I don't know because I didn't read the > implementation. > >> if (ret0 <0) >> handle error, free context, return ret0 >> if (ret1 <0) >> handle error, free context, return ret1 >> if (ret2 <0) >> handle error, free context, return ret2 >> if (ret3 <0) >> handle error, free context, return ret3 >> if (ret4 <0) >> handle error, free context, return ret4 >> if (ret5 <0) >> handle error, free context, return ret5 >> if (ret6 <0) >> handle error, free context, return ret6 >> if (ret7 <0) >> handle error, free context, return ret7 > > Oh come on, why would you need to check av_opt_set calls for options > that are guaranteed to exist? The codebase has hundreds of such > "unchecked" calls. > > And even if you insist that's it's necessary, you wrote it in a way > that makes it look like such error handling is more code. E.g. you > could write: > > if ((ret = av_opt_set_int(...)) < 0) goto error; > > (Or even put all av_opt_set calls into one if condition; it's not like > the error code will be useful anyway.) > >> by this: >> >> context = sws_alloc_set_opts(srcW, srcH, srcFormat, dstW, dstH, >> dstFormat, flags, NULL); >> if (!context) >> handle error >> >> ret = av_opt_set(context, "alphablend", "none", 0); >> >> if (ret <0) >> handle error, free context, return ret >> >> and that looks alot nicer to me, >> but if someone has a even better idea? >> >> > > There's my very old patch, which made libswscale transparently set the > parameters of an input AVFrame. This would actually be the simplest API.
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