PeerStreamer

/*

 * Aura 2 decoder

 *

 * 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

 * Aura 2 decoder

 */

#include "avcodec.h"

typedef struct AuraDecodeContext {

    AVCodecContext *avctx;

    AVFrame frame;

} AuraDecodeContext;

static av_cold int aura_decode_init(AVCodecContext *avctx)

{

    AuraDecodeContext *s = avctx->priv_data;

    s->avctx = avctx;

    /* width needs to be divisible by 4 for this codec to work */

    if (avctx->width & 0x3)

        return -1;

    avctx->pix_fmt = PIX_FMT_YUV422P;

    return 0;

}

static int aura_decode_frame(AVCodecContext *avctx,

                             void *data, int *data_size,

                             AVPacket *pkt)

{

    AuraDecodeContext *s=avctx->priv_data;

    uint8_t *Y, *U, *V;

    uint8_t val;

    int x, y;

    const uint8_t *buf = pkt->data;

    /* prediction error tables (make it clear that they are signed values) */

    const int8_t *delta_table = (const int8_t*)buf + 16;

    if (pkt->size != 48 + avctx->height * avctx->width) {

        av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",

               pkt->size, 48 + avctx->height * avctx->width);

        return -1;

    }

    /* pixel data starts 48 bytes in, after 3x16-byte tables */

    buf += 48;

    if(s->frame.data[0])

        avctx->release_buffer(avctx, &s->frame);

    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;

    s->frame.reference = 0;

    if(avctx->get_buffer(avctx, &s->frame) < 0) {

        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

        return -1;

    }

    Y = s->frame.data[0];

    U = s->frame.data[1];

    V = s->frame.data[2];

    /* iterate through each line in the height */

    for (y = 0; y < avctx->height; y++) {

        /* reset predictors */

        val = *buf++;

        U[0] = val & 0xF0;

        Y[0] = val << 4;

        val = *buf++;

        V[0] = val & 0xF0;

        Y[1] = Y[0] + delta_table[val & 0xF];

        Y += 2; U++; V++;

        /* iterate through the remaining pixel groups (4 pixels/group) */

        for (x = 1; x < (avctx->width >> 1); x++) {

            val = *buf++;

            U[0] = U[-1] + delta_table[val >> 4];

            Y[0] = Y[-1] + delta_table[val & 0xF];

            val = *buf++;

            V[0] = V[-1] + delta_table[val >> 4];

            Y[1] = Y[ 0] + delta_table[val & 0xF];

            Y += 2; U++; V++;

        }

        Y += s->frame.linesize[0] -  avctx->width;

        U += s->frame.linesize[1] - (avctx->width >> 1);

        V += s->frame.linesize[2] - (avctx->width >> 1);

    }

    *data_size=sizeof(AVFrame);

    *(AVFrame*)data= s->frame;

    return pkt->size;

}

static av_cold int aura_decode_end(AVCodecContext *avctx)

{

    AuraDecodeContext *s = avctx->priv_data;

    if (s->frame.data[0])

        avctx->release_buffer(avctx, &s->frame);

    return 0;

}

AVCodec ff_aura2_decoder = {

    "aura2",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_AURA2,

    sizeof(AuraDecodeContext),

    aura_decode_init,

    NULL,

    aura_decode_end,

    aura_decode_frame,

    CODEC_CAP_DR1,

    NULL,

    .long_name = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),

};