/*
 * Sierra VMD Audio & Video Decoders
 * Copyright (C) 2004 the ffmpeg project
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Sierra VMD audio & video decoders
 * by Vladimir "VAG" Gneushev (vagsoft at mail.ru)
 * for more information on the Sierra VMD format, visit:
 *   http://www.pcisys.net/~melanson/codecs/
 *
 * The video decoder outputs PAL8 colorspace data. The decoder expects
 * a 0x330-byte VMD file header to be transmitted via extradata during
 * codec initialization. Each encoded frame that is sent to this decoder
 * is expected to be prepended with the appropriate 16-byte frame
 * information record from the VMD file.
 *
 * The audio decoder, like the video decoder, expects each encoded data
 * chunk to be prepended with the appropriate 16-byte frame information
 * record from the VMD file. It does not require the 0x330-byte VMD file
 * header, but it does need the audio setup parameters passed in through
 * normal libavcodec API means.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#include "internal.h"
#include "bytestream.h"

#define VMD_HEADER_SIZE 0x330
#define PALETTE_COUNT 256

/*
 * Video Decoder
 */

typedef struct VmdVideoContext {

    AVCodecContext *avctx;
    AVFrame *prev_frame;

    const unsigned char *buf;
    int size;

    unsigned char palette[PALETTE_COUNT * 4];
    unsigned char *unpack_buffer;
    int unpack_buffer_size;

    int x_off, y_off;
} VmdVideoContext;

#define QUEUE_SIZE 0x1000
#define QUEUE_MASK 0x0FFF

static int lz_unpack(const unsigned char *src, int src_len,
                      unsigned char *dest, int dest_len)
{
    unsigned char *d;
    unsigned char *d_end;
    unsigned char queue[QUEUE_SIZE];
    unsigned int qpos;
    unsigned int dataleft;
    unsigned int chainofs;
    unsigned int chainlen;
    unsigned int speclen;
    unsigned char tag;
    unsigned int i, j;
    GetByteContext gb;

    bytestream2_init(&gb, src, src_len);
    d = dest;
    d_end = d + dest_len;
    dataleft = bytestream2_get_le32(&gb);
    memset(queue, 0x20, QUEUE_SIZE);
    if (bytestream2_get_bytes_left(&gb) < 4)
        return AVERROR_INVALIDDATA;
    if (bytestream2_peek_le32(&gb) == 0x56781234) {
        bytestream2_skipu(&gb, 4);
        qpos = 0x111;
        speclen = 0xF + 3;
    } else {
        qpos = 0xFEE;
        speclen = 100;  /* no speclen */
    }

    while (dataleft > 0 && bytestream2_get_bytes_left(&gb) > 0) {
        tag = bytestream2_get_byteu(&gb);
        if ((tag == 0xFF) && (dataleft > 8)) {
            if (d_end - d < 8 || bytestream2_get_bytes_left(&gb) < 8)
                return AVERROR_INVALIDDATA;
            for (i = 0; i < 8; i++) {
                queue[qpos++] = *d++ = bytestream2_get_byteu(&gb);
                qpos &= QUEUE_MASK;
            }
            dataleft -= 8;
        } else {
            for (i = 0; i < 8; i++) {
                if (dataleft == 0)
                    break;
                if (tag & 0x01) {
                    if (d_end - d < 1 || bytestream2_get_bytes_left(&gb) < 1)
                        return AVERROR_INVALIDDATA;
                    queue[qpos++] = *d++ = bytestream2_get_byteu(&gb);
                    qpos &= QUEUE_MASK;
                    dataleft--;
                } else {
                    chainofs = bytestream2_get_byte(&gb);
                    chainofs |= ((bytestream2_peek_byte(&gb) & 0xF0) << 4);
                    chainlen = (bytestream2_get_byte(&gb) & 0x0F) + 3;
                    if (chainlen == speclen) {
                        chainlen = bytestream2_get_byte(&gb) + 0xF + 3;
                    }
                    if (d_end - d < chainlen)
                        return AVERROR_INVALIDDATA;
                    for (j = 0; j < chainlen; j++) {
                        *d = queue[chainofs++ & QUEUE_MASK];
                        queue[qpos++] = *d++;
                        qpos &= QUEUE_MASK;
                    }
                    dataleft -= chainlen;
                }
                tag >>= 1;
            }
        }
    }
    return d - dest;
}
static int rle_unpack(const unsigned char *src, unsigned char *dest,
                      int src_count, int src_size, int dest_len)
{
    unsigned char *pd;
    int i, l, used = 0;
    unsigned char *dest_end = dest + dest_len;
    GetByteContext gb;
    uint16_t run_val;

    bytestream2_init(&gb, src, src_size);
    pd = dest;
    if (src_count & 1) {
        if (bytestream2_get_bytes_left(&gb) < 1)
            return 0;
        *pd++ = bytestream2_get_byteu(&gb);
        used++;
    }

    do {
        if (bytestream2_get_bytes_left(&gb) < 1)
            break;
        l = bytestream2_get_byteu(&gb);
        if (l & 0x80) {
            l = (l & 0x7F) * 2;
            if (dest_end - pd < l || bytestream2_get_bytes_left(&gb) < l)
                return bytestream2_tell(&gb);
            bytestream2_get_bufferu(&gb, pd, l);
            pd += l;
        } else {
            if (dest_end - pd < 2*l || bytestream2_get_bytes_left(&gb) < 2)
                return bytestream2_tell(&gb);
            run_val = bytestream2_get_ne16(&gb);
            for (i = 0; i < l; i++) {
                AV_WN16(pd, run_val);
                pd += 2;
            }
            l *= 2;
        }
        used += l;
    } while (used < src_count);

    return bytestream2_tell(&gb);
}

static int vmd_decode(VmdVideoContext *s, AVFrame *frame)
{
    int i;
    unsigned int *palette32;
    unsigned char r, g, b;

    GetByteContext gb;

    unsigned char meth;
    unsigned char *dp;   /* pointer to current frame */
    unsigned char *pp;   /* pointer to previous frame */
    unsigned char len;
    int ofs;

    int frame_x, frame_y;
    int frame_width, frame_height;

    frame_x = AV_RL16(&s->buf[6]);
    frame_y = AV_RL16(&s->buf[8]);
    frame_width = AV_RL16(&s->buf[10]) - frame_x + 1;
    frame_height = AV_RL16(&s->buf[12]) - frame_y + 1;

    if ((frame_width == s->avctx->width && frame_height == s->avctx->height) &&
        (frame_x || frame_y)) {

        s->x_off = frame_x;
        s->y_off = frame_y;
    }
    frame_x -= s->x_off;
    frame_y -= s->y_off;

    if (frame_x < 0 || frame_width < 0 ||
        frame_x >= s->avctx->width ||
        frame_width > s->avctx->width ||
        frame_x + frame_width > s->avctx->width) {
        av_log(s->avctx, AV_LOG_ERROR,
               "Invalid horizontal range %d-%d\n",
               frame_x, frame_width);
        return AVERROR_INVALIDDATA;
    }
    if (frame_y < 0 || frame_height < 0 ||
        frame_y >= s->avctx->height ||
        frame_height > s->avctx->height ||
        frame_y + frame_height > s->avctx->height) {
        av_log(s->avctx, AV_LOG_ERROR,
               "Invalid vertical range %d-%d\n",
               frame_x, frame_width);
        return AVERROR_INVALIDDATA;
    }

    /* if only a certain region will be updated, copy the entire previous
     * frame before the decode */
    if (s->prev_frame->data[0] &&
        (frame_x || frame_y || (frame_width != s->avctx->width) ||
        (frame_height != s->avctx->height))) {

        memcpy(frame->data[0], s->prev_frame->data[0],
            s->avctx->height * frame->linesize[0]);
    }

    /* check if there is a new palette */
    bytestream2_init(&gb, s->buf + 16, s->size - 16);
    if (s->buf[15] & 0x02) {
        bytestream2_skip(&gb, 2);
        palette32 = (unsigned int *)s->palette;
        if (bytestream2_get_bytes_left(&gb) >= PALETTE_COUNT * 3) {
            for (i = 0; i < PALETTE_COUNT; i++) {
                r = bytestream2_get_byteu(&gb) * 4;
                g = bytestream2_get_byteu(&gb) * 4;
                b = bytestream2_get_byteu(&gb) * 4;
                palette32[i] = 0xFFU << 24 | (r << 16) | (g << 8) | (b);
                palette32[i] |= palette32[i] >> 6 & 0x30303;
            }
        } else {
            av_log(s->avctx, AV_LOG_ERROR, "Incomplete palette\n");
            return AVERROR_INVALIDDATA;
        }
    }

    if (!s->size)
        return 0;

    /* originally UnpackFrame in VAG's code */
    if (bytestream2_get_bytes_left(&gb) < 1)
        return AVERROR_INVALIDDATA;
    meth = bytestream2_get_byteu(&gb);
    if (meth & 0x80) {
        int size;
        if (!s->unpack_buffer_size) {
            av_log(s->avctx, AV_LOG_ERROR,
                   "Trying to unpack LZ-compressed frame with no LZ buffer\n");
            return AVERROR_INVALIDDATA;
        }
        size = lz_unpack(gb.buffer, bytestream2_get_bytes_left(&gb),
                         s->unpack_buffer, s->unpack_buffer_size);
        if (size < 0)
            return size;
        meth &= 0x7F;
        bytestream2_init(&gb, s->unpack_buffer, size);
    }

    dp = &frame->data[0][frame_y * frame->linesize[0] + frame_x];
    pp = &s->prev_frame->data[0][frame_y * s->prev_frame->linesize[0] + frame_x];
    switch (meth) {
    case 1:
        for (i = 0; i < frame_height; i++) {
            ofs = 0;
            do {
                len = bytestream2_get_byte(&gb);
                if (len & 0x80) {
                    len = (len & 0x7F) + 1;
                    if (ofs + len > frame_width ||
                        bytestream2_get_bytes_left(&gb) < len)
                        return AVERROR_INVALIDDATA;
                    bytestream2_get_bufferu(&gb, &dp[ofs], len);
                    ofs += len;
                } else {
                    /* interframe pixel copy */
                    if (ofs + len + 1 > frame_width || !s->prev_frame->data[0])
                        return AVERROR_INVALIDDATA;
                    memcpy(&dp[ofs], &pp[ofs], len + 1);
                    ofs += len + 1;
                }
            } while (ofs < frame_width);
            if (ofs > frame_width) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "offset > width (%d > %d)\n",
                       ofs, frame_width);
                return AVERROR_INVALIDDATA;
            }
            dp += frame->linesize[0];
            pp += s->prev_frame->linesize[0];
        }
        break;

    case 2:
        for (i = 0; i < frame_height; i++) {
            bytestream2_get_buffer(&gb, dp, frame_width);
            dp += frame->linesize[0];
            pp += s->prev_frame->linesize[0];
        }
        break;

    case 3:
        for (i = 0; i < frame_height; i++) {
            ofs = 0;
            do {
                len = bytestream2_get_byte(&gb);
                if (len & 0x80) {
                    len = (len & 0x7F) + 1;
                    if (bytestream2_peek_byte(&gb) == 0xFF) {
                        int slen = len;
                        bytestream2_get_byte(&gb);
                        len = rle_unpack(gb.buffer, &dp[ofs],
                                         len, bytestream2_get_bytes_left(&gb),
                                         frame_width - ofs);
                        ofs += slen;
                        bytestream2_skip(&gb, len);
                    } else {
                        if (ofs + len > frame_width ||
                            bytestream2_get_bytes_left(&gb) < len)
                            return AVERROR_INVALIDDATA;
                        bytestream2_get_buffer(&gb, &dp[ofs], len);
                        ofs += len;
                    }
                } else {
                    /* interframe pixel copy */
                    if (ofs + len + 1 > frame_width || !s->prev_frame->data[0])
                        return AVERROR_INVALIDDATA;
                    memcpy(&dp[ofs], &pp[ofs], len + 1);
                    ofs += len + 1;
                }
            } while (ofs < frame_width);
            if (ofs > frame_width) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "offset > width (%d > %d)\n",
                       ofs, frame_width);
                return AVERROR_INVALIDDATA;
            }
            dp += frame->linesize[0];
            pp += s->prev_frame->linesize[0];
        }
        break;
    }
    return 0;
}

static av_cold int vmdvideo_decode_end(AVCodecContext *avctx)
{
    VmdVideoContext *s = avctx->priv_data;

    av_frame_free(&s->prev_frame);
    av_freep(&s->unpack_buffer);
    s->unpack_buffer_size = 0;

    return 0;
}

static av_cold int vmdvideo_decode_init(AVCodecContext *avctx)
{
    VmdVideoContext *s = avctx->priv_data;
    int i;
    unsigned int *palette32;
    int palette_index = 0;
    unsigned char r, g, b;
    unsigned char *vmd_header;
    unsigned char *raw_palette;

    s->avctx = avctx;
    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    /* make sure the VMD header made it */
    if (s->avctx->extradata_size != VMD_HEADER_SIZE) {
        av_log(s->avctx, AV_LOG_ERROR, "expected extradata size of %d\n",
            VMD_HEADER_SIZE);
        return AVERROR_INVALIDDATA;
    }
    vmd_header = (unsigned char *)avctx->extradata;

    s->unpack_buffer_size = AV_RL32(&vmd_header[800]);
    if (s->unpack_buffer_size) {
        s->unpack_buffer = av_malloc(s->unpack_buffer_size);
        if (!s->unpack_buffer)
            return AVERROR(ENOMEM);
    }

    /* load up the initial palette */
    raw_palette = &vmd_header[28];
    palette32 = (unsigned int *)s->palette;
    for (i = 0; i < PALETTE_COUNT; i++) {
        r = raw_palette[palette_index++] * 4;
        g = raw_palette[palette_index++] * 4;
        b = raw_palette[palette_index++] * 4;
        palette32[i] = 0xFFU << 24 | (r << 16) | (g << 8) | (b);
        palette32[i] |= palette32[i] >> 6 & 0x30303;
    }

    s->prev_frame = av_frame_alloc();
    if (!s->prev_frame) {
        vmdvideo_decode_end(avctx);
        return AVERROR(ENOMEM);
    }

    return 0;
}

static int vmdvideo_decode_frame(AVCodecContext *avctx,
                                 void *data, int *got_frame,
                                 AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    VmdVideoContext *s = avctx->priv_data;
    AVFrame *frame = data;
    int ret;

    s->buf = buf;
    s->size = buf_size;

    if (buf_size < 16)
        return AVERROR_INVALIDDATA;

    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
        return ret;

    if ((ret = vmd_decode(s, frame)) < 0)
        return ret;

    /* make the palette available on the way out */
    memcpy(frame->data[1], s->palette, PALETTE_COUNT * 4);

    /* shuffle frames */
    av_frame_unref(s->prev_frame);
    if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
        return ret;

    *got_frame      = 1;

    /* report that the buffer was completely consumed */
    return buf_size;
}

/*
 * Audio Decoder
 */

#define BLOCK_TYPE_AUDIO    1
#define BLOCK_TYPE_INITIAL  2
#define BLOCK_TYPE_SILENCE  3

typedef struct VmdAudioContext {
    int out_bps;
    int chunk_size;
} VmdAudioContext;

static const uint16_t vmdaudio_table[128] = {
    0x000, 0x008, 0x010, 0x020, 0x030, 0x040, 0x050, 0x060, 0x070, 0x080,
    0x090, 0x0A0, 0x0B0, 0x0C0, 0x0D0, 0x0E0, 0x0F0, 0x100, 0x110, 0x120,
    0x130, 0x140, 0x150, 0x160, 0x170, 0x180, 0x190, 0x1A0, 0x1B0, 0x1C0,
    0x1D0, 0x1E0, 0x1F0, 0x200, 0x208, 0x210, 0x218, 0x220, 0x228, 0x230,
    0x238, 0x240, 0x248, 0x250, 0x258, 0x260, 0x268, 0x270, 0x278, 0x280,
    0x288, 0x290, 0x298, 0x2A0, 0x2A8, 0x2B0, 0x2B8, 0x2C0, 0x2C8, 0x2D0,
    0x2D8, 0x2E0, 0x2E8, 0x2F0, 0x2F8, 0x300, 0x308, 0x310, 0x318, 0x320,
    0x328, 0x330, 0x338, 0x340, 0x348, 0x350, 0x358, 0x360, 0x368, 0x370,
    0x378, 0x380, 0x388, 0x390, 0x398, 0x3A0, 0x3A8, 0x3B0, 0x3B8, 0x3C0,
    0x3C8, 0x3D0, 0x3D8, 0x3E0, 0x3E8, 0x3F0, 0x3F8, 0x400, 0x440, 0x480,
    0x4C0, 0x500, 0x540, 0x580, 0x5C0, 0x600, 0x640, 0x680, 0x6C0, 0x700,
    0x740, 0x780, 0x7C0, 0x800, 0x900, 0xA00, 0xB00, 0xC00, 0xD00, 0xE00,
    0xF00, 0x1000, 0x1400, 0x1800, 0x1C00, 0x2000, 0x3000, 0x4000
};

static av_cold int vmdaudio_decode_init(AVCodecContext *avctx)
{
    VmdAudioContext *s = avctx->priv_data;

    if (avctx->channels < 1 || avctx->channels > 2) {
        av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
        return AVERROR(EINVAL);
    }
    if (avctx->block_align < 1 || avctx->block_align % avctx->channels) {
        av_log(avctx, AV_LOG_ERROR, "invalid block align\n");
        return AVERROR(EINVAL);
    }

    avctx->channel_layout = avctx->channels == 1 ? AV_CH_LAYOUT_MONO :
                                                   AV_CH_LAYOUT_STEREO;

    if (avctx->bits_per_coded_sample == 16)
        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
    else
        avctx->sample_fmt = AV_SAMPLE_FMT_U8;
    s->out_bps = av_get_bytes_per_sample(avctx->sample_fmt);

    s->chunk_size = avctx->block_align + avctx->channels * (s->out_bps == 2);

    av_log(avctx, AV_LOG_DEBUG, "%d channels, %d bits/sample, "
           "block align = %d, sample rate = %d\n",
           avctx->channels, avctx->bits_per_coded_sample, avctx->block_align,
           avctx->sample_rate);

    return 0;
}

static void decode_audio_s16(int16_t *out, const uint8_t *buf, int buf_size,
                             int channels)
{
    int ch;
    const uint8_t *buf_end = buf + buf_size;
    int predictor[2];
    int st = channels - 1;

    /* decode initial raw sample */
    for (ch = 0; ch < channels; ch++) {
        predictor[ch] = (int16_t)AV_RL16(buf);
        buf += 2;
        *out++ = predictor[ch];
    }

    /* decode DPCM samples */
    ch = 0;
    while (buf < buf_end) {
        uint8_t b = *buf++;
        if (b & 0x80)
            predictor[ch] -= vmdaudio_table[b & 0x7F];
        else
            predictor[ch] += vmdaudio_table[b];
        predictor[ch] = av_clip_int16(predictor[ch]);
        *out++ = predictor[ch];
        ch ^= st;
    }
}

static int vmdaudio_decode_frame(AVCodecContext *avctx, void *data,
                                 int *got_frame_ptr, AVPacket *avpkt)
{
    AVFrame *frame     = data;
    const uint8_t *buf = avpkt->data;
    const uint8_t *buf_end;
    int buf_size = avpkt->size;
    VmdAudioContext *s = avctx->priv_data;
    int block_type, silent_chunks, audio_chunks;
    int ret;
    uint8_t *output_samples_u8;
    int16_t *output_samples_s16;

    if (buf_size < 16) {
        av_log(avctx, AV_LOG_WARNING, "skipping small junk packet\n");
        *got_frame_ptr = 0;
        return buf_size;
    }

    block_type = buf[6];
    if (block_type < BLOCK_TYPE_AUDIO || block_type > BLOCK_TYPE_SILENCE) {
        av_log(avctx, AV_LOG_ERROR, "unknown block type: %d\n", block_type);
        return AVERROR(EINVAL);
    }
    buf      += 16;
    buf_size -= 16;

    /* get number of silent chunks */
    silent_chunks = 0;
    if (block_type == BLOCK_TYPE_INITIAL) {
        uint32_t flags;
        if (buf_size < 4) {
            av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
            return AVERROR(EINVAL);
        }
        flags         = AV_RB32(buf);
        silent_chunks = av_popcount(flags);
        buf      += 4;
        buf_size -= 4;
    } else if (block_type == BLOCK_TYPE_SILENCE) {
        silent_chunks = 1;
        buf_size = 0; // should already be zero but set it just to be sure
    }

    /* ensure output buffer is large enough */
    audio_chunks = buf_size / s->chunk_size;

    /* drop incomplete chunks */
    buf_size     = audio_chunks * s->chunk_size;

    /* get output buffer */
    frame->nb_samples = ((silent_chunks + audio_chunks) * avctx->block_align) /
                        avctx->channels;
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;
    output_samples_u8  =            frame->data[0];
    output_samples_s16 = (int16_t *)frame->data[0];

    /* decode silent chunks */
    if (silent_chunks > 0) {
        int silent_size = avctx->block_align * silent_chunks;
        av_assert0(avctx->block_align * silent_chunks <= frame->nb_samples * avctx->channels);

        if (s->out_bps == 2) {
            memset(output_samples_s16, 0x00, silent_size * 2);
            output_samples_s16 += silent_size;
        } else {
            memset(output_samples_u8,  0x80, silent_size);
            output_samples_u8 += silent_size;
        }
    }

    /* decode audio chunks */
    if (audio_chunks > 0) {
        buf_end = buf + buf_size;
        av_assert0((buf_size & (avctx->channels > 1)) == 0);
        while (buf_end - buf >= s->chunk_size) {
            if (s->out_bps == 2) {
                decode_audio_s16(output_samples_s16, buf, s->chunk_size,
                                 avctx->channels);
                output_samples_s16 += avctx->block_align;
            } else {
                memcpy(output_samples_u8, buf, s->chunk_size);
                output_samples_u8  += avctx->block_align;
            }
            buf += s->chunk_size;
        }
    }

    *got_frame_ptr = 1;

    return avpkt->size;
}


/*
 * Public Data Structures
 */

AVCodec ff_vmdvideo_decoder = {
    .name           = "vmdvideo",
    .long_name      = NULL_IF_CONFIG_SMALL("Sierra VMD video"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_VMDVIDEO,
    .priv_data_size = sizeof(VmdVideoContext),
    .init           = vmdvideo_decode_init,
    .close          = vmdvideo_decode_end,
    .decode         = vmdvideo_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
};

AVCodec ff_vmdaudio_decoder = {
    .name           = "vmdaudio",
    .long_name      = NULL_IF_CONFIG_SMALL("Sierra VMD audio"),
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_VMDAUDIO,
    .priv_data_size = sizeof(VmdAudioContext),
    .init           = vmdaudio_decode_init,
    .decode         = vmdaudio_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
};