> On Mar 1, 2023, at 06:40, Stefano Sabatini <stefa...@gmail.com> wrote: > > On date Tuesday 2023-02-28 23:28:56 +0100, Stefano Sabatini wrote: >> In particular, clarify how to set options in the codec context, and mention >> when to use >> avcodec_parameters_to_context(). >> >> Fix trac issue http://trac.ffmpeg.org/ticket/5781. >> --- >> libavcodec/avcodec.h | 29 ++++++++++++++++++++++++----- >> 1 file changed, 24 insertions(+), 5 deletions(-) >
> In particular, clarify how to set options in the codec context, and mention > when to use > avcodec_parameters_to_context(). > > Fix trac issues: > http://trac.ffmpeg.org/ticket/5781 > http://trac.ffmpeg.org/ticket/5838 > --- > libavcodec/avcodec.h | 34 +++++++++++++++++++++++++++++----- > 1 file changed, 29 insertions(+), 5 deletions(-) > > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h > index 9a0fe97cad..fbf1d3d83c 100644 > --- a/libavcodec/avcodec.h > +++ b/libavcodec/avcodec.h > @@ -2418,8 +2418,14 @@ int avcodec_parameters_to_context(AVCodecContext > *codec, > * avcodec_find_decoder() and avcodec_find_encoder() provide an easy way for > * retrieving a codec. > * > - * @note Always call this function before using decoding routines (such as > - * @ref avcodec_receive_frame()). > + * Depending on the codec, you might need to set options in the codec context > + * also for decoding (e.g. width, height, or the pixel or audio sample > format in > + * case the information is not is not available in the bitstream, e.g. as in 'is not is not' > + * case of decoding raw audio or video). in ’the’ case of. > + * > + * Options on the codec context can be either set by providing the options > + * specified in an AVDictionary, or by setting the values on the context > itself, > + * directly or by using the av_opt_set() API. > * > * @code > * av_dict_set(&opts, "b", "2.5M", 0); > @@ -2433,17 +2439,35 @@ int avcodec_parameters_to_context(AVCodecContext > *codec, > * exit(1); > * @endcode > * > + * In case AVCodecParameters are available (e.g. when demuxing a stream using > + * libavformat, and accessing the AVStream contained in the demuxer), the > codec > + * parameters can be copied to the codec context using > + * avcodec_parameters_to_context(), as in the following code: > + * > + * @code > + * context = avcodec_alloc_context3(codec); > + * if (avcodec_parameters_to_context(*dec_ctx, codecpar) < 0) > + * exit(1); > + * if (avcodec_open2(context, codec, NULL) < 0) > + * exit(1); What’s the dec_ctx? > + * @endcode > + * > + * @note Always call this function before using decoding routines (such as > + * @ref avcodec_receive_frame()). > + * > * @param avctx The context to initialize. > * @param codec The codec to open this context for. If a non-NULL codec has > been > * previously passed to avcodec_alloc_context3() or > * for this context, then this parameter MUST be either NULL or > * equal to the previously passed codec. > - * @param options A dictionary filled with AVCodecContext and codec-private > options. > - * On return this object will be filled with options that > were not found. > + * @param options A dictionary filled with AVCodecContext and codec-private > + * options, which are set on top of the options already set in > + * avctx, can be NULL. On return this object will be filled > with > + * options that were not found in avctx. > * > * @return zero on success, a negative value on error > * @see avcodec_alloc_context3(), avcodec_find_decoder(), > avcodec_find_encoder(), > - * av_dict_set(), av_opt_find(). > + * av_dict_set(), av_opt_set(), av_opt_find(), > avcodec_parameters_to_context() > */ > int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary > **options); > > -- > 2.25.1 _______________________________________________ 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".
