[ffmpeg] packet

API调用

常用API

AVPacket *av_packet_alloc(void); // 构建 packet 结构体
void av_packet_free(AVPacket **pkt); // 释放 packet 结构体
void av_packet_rescale_ts(AVPacket *pkt, AVRational tb_src, AVRational tb_dst); // pts,dts,duration 基于前后时间基进行转换

结构体介绍

typedef struct AVPacket {
    AVBufferRef *buf; // data 实际保存的地方，通过 ref 控制是否真的释放
    int64_t pts; // 渲染时间，基于 time_base 单位，必须 pts >= dts
    int64_t dts; // 解码时间，基于 time_base 单位 
    uint8_t *data; // 指向 buf->data
    int   size;
    int   stream_index; // 流索引，和 avformat 上下文中的 stream 对应
    int   flags;
    AVPacketSideData *side_data;
    int side_data_elems;
    int64_t duration; // 渲染时间，基于 time_base 单位。等于 next_pts - this_pts
    int64_t pos; // 在流中的位置
    void *opaque; // 私有数据
    AVBufferRef *opaque_ref;
    AVRational time_base; // 时间基，视频为 1/fps 
} AVPacket;

struct AVBuffer {
    uint8_t *data; /**< data described by this buffer */
    size_t size; /**< size of data in bytes */
    atomic_uint refcount;
    void (*free)(void *opaque, uint8_t *data);
    void *opaque;
    int flags;
    int flags_internal;
};

其他

AVPacket *av_packet_alloc(void);
AVPacket *av_packet_clone(const AVPacket *src);
void av_packet_free(AVPacket **pkt);
void av_init_packet(AVPacket *pkt);
int av_new_packet(AVPacket *pkt, int size);
void av_shrink_packet(AVPacket *pkt, int size);
int av_grow_packet(AVPacket *pkt, int grow_by);
int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size);
uint8_t* av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type, size_t size);
int av_packet_add_side_data(AVPacket *pkt, enum AVPacketSideDataType type, uint8_t *data, size_t size);
int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type, size_t size);
uint8_t* av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type, size_t *size);
const char *av_packet_side_data_name(enum AVPacketSideDataType type);
uint8_t *av_packet_pack_dictionary(AVDictionary *dict, size_t *size);
int av_packet_unpack_dictionary(const uint8_t *data, size_t size, AVDictionary **dict);
void av_packet_free_side_data(AVPacket *pkt);
int av_packet_ref(AVPacket *dst, const AVPacket *src);
void av_packet_unref(AVPacket *pkt);
void av_packet_move_ref(AVPacket *dst, AVPacket *src);
int av_packet_copy_props(AVPacket *dst, const AVPacket *src);
int av_packet_make_refcounted(AVPacket *pkt);
int av_packet_make_writable(AVPacket *pkt);
void av_packet_rescale_ts(AVPacket *pkt, AVRational tb_src, AVRational tb_dst);