typedef struct AVCodec {
    /**
     * Name of the codec implementation.
     * The name is globally unique among encoders and among decoders (but an
     * encoder and a decoder can share the same name).
     * This is the primary way to find a codec from the user perspective.
     */
    const char *name;
    /**
     * Descriptive name for the codec, meant to be more human readable than name.
     * You should use the NULL_IF_CONFIG_SMALL() macro to define it.
     */
    const char *long_name;
    enum AVMediaType type;
    enum AVCodecID id;
    /**
     * Codec capabilities.
     * see CODEC_CAP_*
     */
    int capabilities;
    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
    const uint64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
#if FF_API_LOWRES
    attribute_deprecated uint8_t max_lowres; ///< maximum value for lowres supported by the decoder
#endif
    const AVClass *priv_class;              ///< AVClass for the private context
    const AVProfile *profiles;              ///< array of recognized profiles, or NULL if unknown, array is terminated by {FF_PROFILE_UNKNOWN}

    /*****************************************************************
     * No fields below this line are part of the public API. They
     * may not be used outside of libavcodec and can be changed and
     * removed at will.
     * New public fields should be added right above.
     *****************************************************************
     */
    int priv_data_size;
    struct AVCodec *next;
    /**
     * @name Frame-level threading support functions
     * @{
     */
    /**
     * If defined, called on thread contexts when they are created.
     * If the codec allocates writable tables in init(), re-allocate them here.
     * priv_data will be set to a copy of the original.
     */
    int (*init_thread_copy)(AVCodecContext *);
    /**
     * Copy necessary context variables from a previous thread context to the current one.
     * If not defined, the next thread will start automatically; otherwise, the codec
     * must call ff_thread_finish_setup().
     *
     * dst and src will (rarely) point to the same context, in which case memcpy should be skipped.
     */
    int (*update_thread_context)(AVCodecContext *dst, const AVCodecContext *src);
    /** @} */

    /**
     * Private codec-specific defaults.
     */
    const AVCodecDefault *defaults;

    /**
     * Initialize codec static data, called from avcodec_register().
     */
    void (*init_static_data)(struct AVCodec *codec);

    int (*init)(AVCodecContext *);
    int (*encode_sub)(AVCodecContext *, uint8_t *buf, int buf_size,
                      const struct AVSubtitle *sub);
    /**
     * Encode data to an AVPacket.
     *
     * @param      avctx          codec context
     * @param      avpkt          output AVPacket (may contain a user-provided buffer)
     * @param[in]  frame          AVFrame containing the raw data to be encoded
     * @param[out] got_packet_ptr encoder sets to 0 or 1 to indicate that a
     *                            non-empty packet was returned in avpkt.
     * @return 0 on success, negative error code on failure
     */
    int (*encode2)(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame,
                   int *got_packet_ptr);
    int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
    int (*close)(AVCodecContext *);
    /**
     * Flush buffers.
     * Will be called when seeking
     */
    void (*flush)(AVCodecContext *);
} AVCodec;

OBJS-$(CONFIG_VP8_DECODER)             += vp8.o vp8dsp.o vp56rac.o
OBJS-$(CONFIG_VP9_DECODER)             += vp9.o vp9data.o vp9dsp.o \
                                          vp9block.o vp9prob.o vp9mvs.o vp56rac.o

vp8_decoder_select="h264pred videodsp"
vp9_decoder_select="videodsp"

struct SliceData {
    int y;
    int colour;
};

/* simply draw something in slice */
static void worker(AVCodecContext *avctx, void *arg2)
{
    LocalCodecContext *c = avctx->priv_data;
    struct SliceData *sd = arg2;
    int i;

    for (i = 0; i < 20; i++)
        c->frame->data[0][i + sd->y * c->frame->linesize[0]] = sd->colour;
}

/* let's assume we have N slices */
static void decode_slices(AVCodecContext *avctx)
{
    int i;
    LocalCodecContext *c = avctx->priv_data;
    struct SliceData *data = c->slice_data;

    for (i = 0; i < N; i++) {
        data[i].y = avctx->width * i / N;
        data[i].colour = i * 3 + N;
    }

    avctx->execute(avctx, worker, data, NULL, N, sizeof(data[0]));
}

#include "thread.h"

static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                        AVPacket *avpkt)
{
    ThreadFrame frame = { .f = data };

    if ((ret = ff_thread_get_buffer(avctx, &frame, 0)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return ret;
    }

    ff_thread_finish_setup(avctx);

    // continue working with frame.f as usual
    ...
}

static const int twolame_samplerates[] = {
    16000, 22050, 24000, 32000, 44100, 48000, 0
};

...

    .sample_fmts    = (const enum AVSampleFormat[]) {
        AV_SAMPLE_FMT_FLT,
        AV_SAMPLE_FMT_FLTP,
        AV_SAMPLE_FMT_S16,
        AV_SAMPLE_FMT_S16P,
        AV_SAMPLE_FMT_NONE
    },
    .channel_layouts = (const uint64_t[]) {
        AV_CH_LAYOUT_MONO,
        AV_CH_LAYOUT_STEREO,
        0 },
    .supported_samplerates = twolame_samplerates,