On date Saturday 2023-09-02 22:07:53 +0200, Michael Niedermayer wrote: > On Fri, Sep 01, 2023 at 08:38:26PM +0200, Stefano Sabatini wrote: > > On date Friday 2023-09-01 18:54:40 +0200, Michael Niedermayer wrote: > > > On Thu, Aug 31, 2023 at 07:16:20PM +0200, Stefano Sabatini wrote: > > [...] > > > > +/** > > > > + * Compute and return a normalized Gaussian vector. > > > > + * > > > > + * @param vecp: pointer where the computed vector is put in case of > > > > + * success > > > > + * @param standard_deviation the standard deviation used to generate > > > > + * the Gaussian vector, must be a non-negative value > > > > + * @param quality the quality of the generated Gaussian vector, must > > > > + * be a non-negative value. It affects the lenght of the > > > > generated > > > > + * vector. A value equal to 3 corresponds to high quality. > > > > + * @param log_ctx a pointer to an arbitrary struct of which the first > > > > + * field is a pointer to an AVClass struct (used for av_log) > > > > + * used for logging, can be NULL > > > > + * > > > > + * @return a negative error code on error, non negative otherwise > > > > + */ > > > > +int sws_get_gaussian_vec(SwsVector **vecp, > > > > + double standard_deviation, double quality, > > > > + void *log_ctx); > > > > > > which of the two do you consider better? > > > > > > First, here the central part we return is the vector > > > > > > SwsVector *gaus_vec = sws_getGaussianVec(NULL, 1, 2); > > > SwsVector *temp_vec = sws_ConvolveVec(NULL, in_vec, gaus_vec); > > > sws_averageVec(temp_vec, temp_vec, in_vec); > > > > > > av_free(gaus_vec); > > > return temp_vec; // Error checking here happens by temp_vec being NULL in > > > all cases of error > > > > > > vs. > > > > > > Second, here the central part we return is the error code > > > > > > SwsVector *gaus_vec = NULL; > > > SwsVector *temp_vec = NULL; > > > int err = sws_getGaussianVec(&gaus_vec, 1, 2); > > > if (err<0) > > > goto fail; > > > > > > err = sws_ConvolveVec(&temp_vec, in_vec, gaus_vec); > > > if (err<0) > > > goto fail; > > > > > > err = sws_averageVec(&temp_vec, temp_vec, in_vec); > > > if (err<0) > > > goto fail; > > > > The latter pattern enables differentiation between error codes (ENOMEM > > or EINVAL) and provides feedback in the log message. With the former > > you only know if it fails, but you don't know why (relevant in case > > e.g. we make the parameter tunable by a filter and we don't want to > > add additional validation and logging at the filter level). >
> can the API be designed so that optionally the user could choose to > only check the error code after several steps ? > (this would avoid the need for 1 check per call where the fine grained > information is not needed) > I mean similar to the concept of NAN in floating point so that a failure > can be propagated and only at the end checked. Well, with the new approach you can do: SwsVector *gaus_vec, *temp_vec, *avg_vec; sws_get_gaussian_vec(&gaus_vec, 1, 2); sws_get_convolution_vec(&temp_vec, in_vec, gaus_vec); sws_get_average_vec(&avg_vec, temp_vec, in_vec); av_free(gaus_vec); av_free(temp_vec); return avg_vec; // Error checking here happens by avg_vec being NULL in all cases of error If you want to disable the log we could add a log_ctx_offset parameter. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
