Niklas Haas:
> From: Niklas Haas <g...@haasn.dev>
>
> This replaces the myriad of existing lists in AVCodec by a unified API
> call, allowing us to (ultimately) trim down the sizeof(AVCodec) quite
> substantially, while also making this more trivially extensible.
>
> In addition to the already covered lists, add two new entries for color
> space and color range, mirroring the newly added negotiable fields in
> libavfilter.
>
> I decided to drop the explicit length field from the API proposed by
> Andreas Rheinhardt, because having it in place ended up complicating
> both the codec side and the client side implementations, while also
> being strictly less flexible (it's trivial to recover a length given
> a terminator, but requires allocation to add a terminator given
> a length). Using a terminator also presents less of a porting challenge
> for existing users of the current API.
>
> Once the deprecation period passes for the existing public fields, the
> rough plan is to move the commonly used fields (such as
> pix_fmt/sample_fmt) into FFCodec, possibly as a union of audio and video
> configuration types, and then implement the rarely used fields with
> custom callbacks.
> ---
> doc/APIchanges | 5 +++
> libavcodec/avcodec.c | 75 +++++++++++++++++++++++++++++++++++++
> libavcodec/avcodec.h | 27 +++++++++++++
> libavcodec/codec.h | 19 ++++++++--
> libavcodec/codec_internal.h | 24 ++++++++++++
> libavcodec/version.h | 4 +-
> 6 files changed, 148 insertions(+), 6 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 0a39b6d7ab8..fdeae67159d 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -2,6 +2,11 @@ The last version increases of all libraries were on
> 2024-03-07
>
> API changes, most recent first:
>
> +2024-04-xx - xxxxxxxxxx - lavc 59.6.100 - avcodec.h
> + Add avcodec_get_supported_config() and enum AVCodecConfig; deprecate
> + AVCodec.pix_fmts, AVCodec.sample_fmts, AVCodec.supported_framerates,
> + AVCodec.supported_samplerates and AVCodec.ch_layouts.
> +
> 2024-04-03 - xxxxxxxxxx - lavu 59.13.100 - pixfmt.h
> Add AVCOL_SPC_IPT_C2, AVCOL_SPC_YCGCO_RE and AVCOL_SPC_YCGCO_RO
> to map new matrix coefficients defined by H.273 v3.
> diff --git a/libavcodec/avcodec.c b/libavcodec/avcodec.c
> index 525fe516bd2..96728546d6c 100644
> --- a/libavcodec/avcodec.c
> +++ b/libavcodec/avcodec.c
> @@ -700,3 +700,78 @@ int attribute_align_arg
> avcodec_receive_frame(AVCodecContext *avctx, AVFrame *fr
> return ff_decode_receive_frame(avctx, frame);
> return ff_encode_receive_frame(avctx, frame);
> }
> +
> +#define WRAP_CONFIG(allowed_type, field) \
> + do { \
> + if (codec->type != (allowed_type)) \
> + return AVERROR(EINVAL); \
> + *out_configs = (field); \
> + return 0; \
> + } while (0)
> +
> +static const enum AVColorRange color_range_jpeg[] = {
> + AVCOL_RANGE_JPEG, AVCOL_RANGE_UNSPECIFIED
> +};
> +
> +static const enum AVColorRange color_range_mpeg[] = {
> + AVCOL_RANGE_MPEG, AVCOL_RANGE_UNSPECIFIED
> +};
> +
> +static const enum AVColorRange color_range_all[] = {
> + AVCOL_RANGE_MPEG, AVCOL_RANGE_JPEG, AVCOL_RANGE_UNSPECIFIED
> +};
> +
> +static const enum AVColorRange *color_range_table[] = {
> + [AVCOL_RANGE_MPEG] = color_range_mpeg,
> + [AVCOL_RANGE_JPEG] = color_range_jpeg,
> + [AVCOL_RANGE_MPEG | AVCOL_RANGE_JPEG] = color_range_all,
> +};
> +
> +int ff_default_get_supported_config(const AVCodecContext *avctx,
> + const AVCodec *codec,
> + enum AVCodecConfig config,
> + unsigned flags,
> + const void **out_configs)
> +{
> + switch (config) {
> +FF_DISABLE_DEPRECATION_WARNINGS
> + case AV_CODEC_CONFIG_PIX_FORMAT:
> + WRAP_CONFIG(AVMEDIA_TYPE_VIDEO, codec->pix_fmts);
> + case AV_CODEC_CONFIG_FRAME_RATE:
> + WRAP_CONFIG(AVMEDIA_TYPE_VIDEO, codec->supported_framerates);
> + case AV_CODEC_CONFIG_SAMPLE_RATE:
> + WRAP_CONFIG(AVMEDIA_TYPE_AUDIO, codec->supported_samplerates);
> + case AV_CODEC_CONFIG_SAMPLE_FORMAT:
> + WRAP_CONFIG(AVMEDIA_TYPE_AUDIO, codec->sample_fmts);
> + case AV_CODEC_CONFIG_CHANNEL_LAYOUT:
> + WRAP_CONFIG(AVMEDIA_TYPE_AUDIO, codec->ch_layouts);
> +FF_ENABLE_DEPRECATION_WARNINGS
> +
> + case AV_CODEC_CONFIG_COLOR_RANGE:
> + if (codec->type != AVMEDIA_TYPE_VIDEO)
> + return AVERROR(EINVAL);
> + *out_configs = color_range_table[ffcodec(codec)->color_ranges];
> + return 0;
> +
> + case AV_CODEC_CONFIG_COLOR_SPACE:
> + *out_configs = NULL;
> + return 0;
> + default:
> + return AVERROR(EINVAL);
> + }
> +}
> +
> +int avcodec_get_supported_config(const AVCodecContext *avctx, const AVCodec
> *codec,
> + enum AVCodecConfig config, unsigned flags,
> + const void **out)
> +{
> + const FFCodec *codec2;
> + if (!codec)
> + codec = avctx->codec;
> + codec2 = ffcodec(codec);
> + if (codec2->get_supported_config) {
> + return codec2->get_supported_config(avctx, codec, config, flags,
> out);
> + } else {
> + return ff_default_get_supported_config(avctx, codec, config, flags,
> out);
> + }
> +}
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 83dc487251c..64f31375fc6 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -2690,6 +2690,33 @@ int avcodec_get_hw_frames_parameters(AVCodecContext
> *avctx,
> enum AVPixelFormat hw_pix_fmt,
> AVBufferRef **out_frames_ref);
>
> +enum AVCodecConfig {
> + AV_CODEC_CONFIG_PIX_FORMAT, ///< AVPixelFormat, terminated by
> AV_PIX_FMT_NONE
> + AV_CODEC_CONFIG_FRAME_RATE, ///< AVRational, terminated by {0, 0}
> + AV_CODEC_CONFIG_SAMPLE_RATE, ///< int, terminated by 0
> + AV_CODEC_CONFIG_SAMPLE_FORMAT, ///< AVSampleFormat, terminated by
> AV_SAMPLE_FMT_NONE
> + AV_CODEC_CONFIG_CHANNEL_LAYOUT, ///< AVChannelLayout, terminated by {0}
> + AV_CODEC_CONFIG_COLOR_RANGE, ///< AVColorRange, terminated by
> AVCOL_RANGE_UNSPECIFIED
> + AV_CODEC_CONFIG_COLOR_SPACE, ///< AVColorSpace, terminated by
> AVCOL_SPC_UNSPECIFIED
> +};
> +
> +/**
> + * Retrieve a list of all supported values for a given configuration type.
> + *
> + * @param avctx An optional context to use. Values such as
> + * `strict_std_compliance` may affect the result. If NULL,
> + * default values are used.
> + * @param codec The codec to query, or NULL to use avctx->codec.
> + * @param config The configuration to query.
> + * @param flags Currently unused; should be set to zero.
> + * @param out_configs On success, set to a list of configurations, terminated
> + * by a config-specific terminator, or NULL if all
> + * possible values are supported.
> + */
> +int avcodec_get_supported_config(const AVCodecContext *avctx,
> + const AVCodec *codec, enum AVCodecConfig
> config,
> + unsigned flags, const void **out_configs);
1. This approach constrains us in several ways, most notably it forces
us to always have static lists for every possible combination. E.g. take
a look at the wavpack encoder: It accepts certain native channel layouts
or certain unspecified channel counts within a range (the encoder
accepts up to 255, the format allows up to 4096). It makes no sense to
have a static list of 4096 unspecified channel layouts. Getting rid of
this requirement seems good, even if it causes allocations.
2. A length field is not "strictly less flexible", to the contrary: It
allows to keep our options open. The length field should be optional and
for the convenience of the user (meaning the list would still be
terminated by a sentinel). But it would allow to e.g. add a flag in the
future that says that *out_configs is already set to some array whose
length is given by the length field which would allow to avoid the
allocation that I just proposed in 1. (e.g. the number of sample formats
is very small and can be put into a stack array; the number of pixel
formats is also small and can be queried at runtime, so that an array of
maximum size can be allocated once to query multiple codecs).
> +
>
>
> /**
> diff --git a/libavcodec/codec.h b/libavcodec/codec.h
> index 6f9b42760d7..f7541ffc42b 100644
> --- a/libavcodec/codec.h
> +++ b/libavcodec/codec.h
> @@ -205,10 +205,19 @@ typedef struct AVCodec {
> */
> int capabilities;
> uint8_t max_lowres; ///< maximum value for lowres
> supported by the decoder
> - const AVRational *supported_framerates; ///< array of supported
> framerates, or NULL if any, array is terminated by {0,0}
> - const enum AVPixelFormat *pix_fmts; ///< array of supported pixel
> formats, or NULL if unknown, array is terminated by -1
> - const int *supported_samplerates; ///< array of supported audio
> samplerates, or NULL if unknown, array is terminated by 0
> - const enum AVSampleFormat *sample_fmts; ///< array of supported sample
> formats, or NULL if unknown, array is terminated by -1
> +
> + /**
> + * Deprecated codec capabilities.
> + */
> + attribute_deprecated
> + const AVRational *supported_framerates; ///< @deprecated use
> avcodec_get_supported_config()
> + attribute_deprecated
> + const enum AVPixelFormat *pix_fmts; ///< @deprecated use
> avcodec_get_supported_config()
> + attribute_deprecated
> + const int *supported_samplerates; ///< @deprecated use
> avcodec_get_supported_config()
> + attribute_deprecated
> + const enum AVSampleFormat *sample_fmts; ///< @deprecated use
> avcodec_get_supported_config()
> +
> const AVClass *priv_class; ///< AVClass for the private
> context
> const AVProfile *profiles; ///< array of recognized
> profiles, or NULL if unknown, array is terminated by {AV_PROFILE_UNKNOWN}
>
> @@ -226,7 +235,9 @@ typedef struct AVCodec {
>
> /**
> * Array of supported channel layouts, terminated with a zeroed layout.
> + * @deprecated use avcodec_get_supported_config()
> */
> + attribute_deprecated
> const AVChannelLayout *ch_layouts;
> } AVCodec;
>
> diff --git a/libavcodec/codec_internal.h b/libavcodec/codec_internal.h
> index 2134f184094..bac3e30ba2c 100644
> --- a/libavcodec/codec_internal.h
> +++ b/libavcodec/codec_internal.h
> @@ -22,6 +22,7 @@
> #include <stdint.h>
>
> #include "libavutil/attributes.h"
> +#include "avcodec.h"
> #include "codec.h"
> #include "config.h"
>
> @@ -270,8 +271,31 @@ typedef struct FFCodec {
> * List of supported codec_tags, terminated by FF_CODEC_TAGS_END.
> */
> const uint32_t *codec_tags;
> +
> + /**
> + * Custom callback for avcodec_get_supported_config(). If absent,
> + * ff_default_get_supported_config() will be used.
> + */
> + int (*get_supported_config)(const AVCodecContext *avctx,
> + const AVCodec *codec,
> + enum AVCodecConfig config,
> + unsigned flags,
> + const void **out_configs);
> } FFCodec;
>
> +/**
> + * Default implementation for avcodec_get_supported_config(). Will return the
> + * relevant fields from AVCodec if present, or NULL otherwise.
> + *
> + * For AVCODEC_CONFIG_COLOR_RANGE, the output will depend on the bitmask in
> + * FFCodec.color_ranges, with a value of 0 returning NULL.
> + */
> +int ff_default_get_supported_config(const AVCodecContext *avctx,
> + const AVCodec *codec,
> + enum AVCodecConfig config,
> + unsigned flags,
> + const void **out_configs);
> +
> #if CONFIG_SMALL
> #define CODEC_LONG_NAME(str) .p.long_name = NULL
> #else
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index 84a1c02ce4a..da54f878874 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -29,8 +29,8 @@
>
> #include "version_major.h"
>
> -#define LIBAVCODEC_VERSION_MINOR 5
> -#define LIBAVCODEC_VERSION_MICRO 101
> +#define LIBAVCODEC_VERSION_MINOR 6
> +#define LIBAVCODEC_VERSION_MICRO 100
>
> #define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
> LIBAVCODEC_VERSION_MINOR, \
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