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[82.8.130.139]) by smtp.gmail.com with ESMTPSA id w16sm14706791wrg.95.2020.07.27.09.32.44 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jul 2020 09:32:44 -0700 (PDT) From: Mark Thompson To: ffmpeg-devel@ffmpeg.org Date: Mon, 27 Jul 2020 17:32:18 +0100 Message-Id: <20200727163237.23371-4-sw@jkqxz.net> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200727163237.23371-1-sw@jkqxz.net> References: <20200727163237.23371-1-sw@jkqxz.net> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH v6 03/22] cbs: Describe allocate/free methods in tabular form X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Unit types are split into three categories, depending on how their content is managed: * POD structure - these require no special treatment. * Structure containing references to refcounted buffers - these can use a common free function when the offsets of all the internal references are known. * More complex structures - these still require ad-hoc treatment. For each codec we can then maintain a table of descriptors for each set of equivalent unit types, defining the mechanism needed to allocate/free that unit content. This is not required to be used immediately - a new alloc function supports this, but does not replace the old one which works without referring to these tables. --- libavcodec/cbs.c | 69 +++++++++++++++++++++++++++++++++++++++ libavcodec/cbs.h | 9 +++++ libavcodec/cbs_internal.h | 61 ++++++++++++++++++++++++++++++++++ 3 files changed, 139 insertions(+) diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c index 6464980c8e..61cf8e3466 100644 --- a/libavcodec/cbs.c +++ b/libavcodec/cbs.c @@ -802,3 +802,72 @@ void ff_cbs_delete_unit(CodedBitstreamFragment *frag, frag->units + position + 1, (frag->nb_units - position) * sizeof(*frag->units)); } + +static void cbs_default_free_unit_content(void *opaque, uint8_t *data) +{ + const CodedBitstreamUnitTypeDescriptor *desc = opaque; + if (desc->content_type == CBS_CONTENT_TYPE_INTERNAL_REFS) { + int i; + for (i = 0; i < desc->nb_ref_offsets; i++) { + void **ptr = (void**)(data + desc->ref_offsets[i]); + av_buffer_unref((AVBufferRef**)(ptr + 1)); + } + } + av_free(data); +} + +static const CodedBitstreamUnitTypeDescriptor + *cbs_find_unit_type_desc(CodedBitstreamContext *ctx, + CodedBitstreamUnit *unit) +{ + const CodedBitstreamUnitTypeDescriptor *desc; + int i, j; + + if (!ctx->codec->unit_types) + return NULL; + + for (i = 0;; i++) { + desc = &ctx->codec->unit_types[i]; + if (desc->nb_unit_types == 0) + break; + if (desc->nb_unit_types == CBS_UNIT_TYPE_RANGE) { + if (unit->type >= desc->unit_type_range_start && + unit->type <= desc->unit_type_range_end) + return desc; + } else { + for (j = 0; j < desc->nb_unit_types; j++) { + if (desc->unit_types[j] == unit->type) + return desc; + } + } + } + return NULL; +} + +int ff_cbs_alloc_unit_content2(CodedBitstreamContext *ctx, + CodedBitstreamUnit *unit) +{ + const CodedBitstreamUnitTypeDescriptor *desc; + + av_assert0(!unit->content && !unit->content_ref); + + desc = cbs_find_unit_type_desc(ctx, unit); + if (!desc) + return AVERROR(ENOSYS); + + unit->content = av_mallocz(desc->content_size); + if (!unit->content) + return AVERROR(ENOMEM); + + unit->content_ref = + av_buffer_create(unit->content, desc->content_size, + desc->content_free ? desc->content_free + : cbs_default_free_unit_content, + (void*)desc, 0); + if (!unit->content_ref) { + av_freep(&unit->content); + return AVERROR(ENOMEM); + } + + return 0; +} diff --git a/libavcodec/cbs.h b/libavcodec/cbs.h index 07faf18c5b..ea8d942894 100644 --- a/libavcodec/cbs.h +++ b/libavcodec/cbs.h @@ -349,6 +349,15 @@ int ff_cbs_alloc_unit_content(CodedBitstreamUnit *unit, size_t size, void (*free)(void *opaque, uint8_t *content)); +/** + * Allocate a new internal content buffer matching the type of the unit. + * + * The content will be zeroed. + */ +int ff_cbs_alloc_unit_content2(CodedBitstreamContext *ctx, + CodedBitstreamUnit *unit); + + /** * Allocate a new internal data buffer of the given size in the unit. * diff --git a/libavcodec/cbs_internal.h b/libavcodec/cbs_internal.h index 4c5a535ca6..282492bc88 100644 --- a/libavcodec/cbs_internal.h +++ b/libavcodec/cbs_internal.h @@ -25,11 +25,72 @@ #include "put_bits.h" +enum CBSContentType { + // Unit content is a simple structure. + CBS_CONTENT_TYPE_POD, + // Unit content contains some references to other structures, but all + // managed via buffer reference counting. The descriptor defines the + // structure offsets of every buffer reference. + CBS_CONTENT_TYPE_INTERNAL_REFS, + // Unit content is something more complex. The descriptor defines + // special functions to manage the content. + CBS_CONTENT_TYPE_COMPLEX, +}; + +enum { + // Maximum number of unit types described by the same unit type + // descriptor. + CBS_MAX_UNIT_TYPES = 3, + // Maximum number of reference buffer offsets in any one unit. + CBS_MAX_REF_OFFSETS = 2, + // Special value used in a unit type descriptor to indicate that it + // applies to a large range of types rather than a set of discrete + // values. + CBS_UNIT_TYPE_RANGE = -1, +}; + +typedef const struct CodedBitstreamUnitTypeDescriptor { + // Number of entries in the unit_types array, or the special value + // CBS_UNIT_TYPE_RANGE to indicate that the range fields should be + // used instead. + int nb_unit_types; + + // Array of unit types that this entry describes. + const CodedBitstreamUnitType unit_types[CBS_MAX_UNIT_TYPES]; + + // Start and end of unit type range, used if nb_unit_types is + // CBS_UNIT_TYPE_RANGE. + const CodedBitstreamUnitType unit_type_range_start; + const CodedBitstreamUnitType unit_type_range_end; + + // The type of content described. + enum CBSContentType content_type; + // The size of the structure which should be allocated to contain + // the decomposed content of this type of unit. + size_t content_size; + + // Number of entries in the ref_offsets array. Only used if the + // content_type is CBS_CONTENT_TYPE_INTERNAL_REFS. + int nb_ref_offsets; + // The structure must contain two adjacent elements: + // type *field; + // AVBufferRef *field_ref; + // where field points to something in the buffer referred to by + // field_ref. This offset is then set to offsetof(struct, field). + size_t ref_offsets[CBS_MAX_REF_OFFSETS]; + + void (*content_free)(void *opaque, uint8_t *data); +} CodedBitstreamUnitTypeDescriptor; + typedef struct CodedBitstreamType { enum AVCodecID codec_id; size_t priv_data_size; + // List of unit type descriptors for this codec. + // Terminated by a descriptor with nb_unit_types equal to zero. + const CodedBitstreamUnitTypeDescriptor *unit_types; + // Split frag->data into coded bitstream units, creating the // frag->units array. Fill data but not content on each unit. // The header argument should be set if the fragment came from