| Message ID | 20230228222856.39722-1-stefasab@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] lavc/avcodec.h: extend documentation for avcodec_open2() | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
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(-) Updated with some more information, after I realized there was another related issue.
> On Mar 1, 2023, at 06:40, Stefano Sabatini <stefasab@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
On date Wednesday 2023-03-01 15:04:16 +0800, "zhilizhao(赵志立)" wrote: > > 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? Updated, thanks for the feedback.
On date Sunday 2023-03-05 12:57:38 +0100, Stefano Sabatini wrote: > On date Wednesday 2023-03-01 15:04:16 +0800, "zhilizhao(赵志立)" wrote: [...] > Updated, thanks for the feedback. > From 672de0e5d15ab8a22f3957222680d847f60bced8 Mon Sep 17 00:00:00 2001 > From: Stefano Sabatini <stefasab@gmail.com> > Date: Tue, 28 Feb 2023 23:26:43 +0100 > Subject: [PATCH 1/2] lavc/avcodec.h: extend documentation for avcodec_open2() > > 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 | 36 +++++++++++++++++++++++++++++++----- > 1 file changed, 31 insertions(+), 5 deletions(-) Applied with a few minor fixes.
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h index 9a0fe97cad..2b7fb27721 100644 --- a/libavcodec/avcodec.h +++ b/libavcodec/avcodec.h @@ -2418,8 +2418,9 @@ 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()). + * 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 +2434,35 @@ 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); + * @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);