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ffmpeg / libavcodec / aura.c @ 2912e87a

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/*
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 * Aura 2 decoder
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * Aura 2 decoder
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 */
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#include "avcodec.h"
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typedef struct AuraDecodeContext {
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    AVCodecContext *avctx;
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    AVFrame frame;
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} AuraDecodeContext;
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static av_cold int aura_decode_init(AVCodecContext *avctx)
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{
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    AuraDecodeContext *s = avctx->priv_data;
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    s->avctx = avctx;
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    /* width needs to be divisible by 4 for this codec to work */
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    if (avctx->width & 0x3)
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        return -1;
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    avctx->pix_fmt = PIX_FMT_YUV422P;
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    return 0;
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}
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static int aura_decode_frame(AVCodecContext *avctx,
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                             void *data, int *data_size,
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                             AVPacket *pkt)
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{
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    AuraDecodeContext *s=avctx->priv_data;
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    uint8_t *Y, *U, *V;
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    uint8_t val;
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    int x, y;
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    const uint8_t *buf = pkt->data;
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    /* prediction error tables (make it clear that they are signed values) */
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    const int8_t *delta_table = (const int8_t*)buf + 16;
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    if (pkt->size != 48 + avctx->height * avctx->width) {
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        av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
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               pkt->size, 48 + avctx->height * avctx->width);
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        return -1;
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    }
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    /* pixel data starts 48 bytes in, after 3x16-byte tables */
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    buf += 48;
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    if(s->frame.data[0])
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        avctx->release_buffer(avctx, &s->frame);
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    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
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    s->frame.reference = 0;
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    if(avctx->get_buffer(avctx, &s->frame) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        return -1;
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    }
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    Y = s->frame.data[0];
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    U = s->frame.data[1];
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    V = s->frame.data[2];
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    /* iterate through each line in the height */
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    for (y = 0; y < avctx->height; y++) {
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        /* reset predictors */
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        val = *buf++;
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        U[0] = val & 0xF0;
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        Y[0] = val << 4;
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        val = *buf++;
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        V[0] = val & 0xF0;
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        Y[1] = Y[0] + delta_table[val & 0xF];
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        Y += 2; U++; V++;
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        /* iterate through the remaining pixel groups (4 pixels/group) */
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        for (x = 1; x < (avctx->width >> 1); x++) {
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            val = *buf++;
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            U[0] = U[-1] + delta_table[val >> 4];
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            Y[0] = Y[-1] + delta_table[val & 0xF];
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            val = *buf++;
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            V[0] = V[-1] + delta_table[val >> 4];
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            Y[1] = Y[ 0] + delta_table[val & 0xF];
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            Y += 2; U++; V++;
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        }
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        Y += s->frame.linesize[0] -  avctx->width;
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        U += s->frame.linesize[1] - (avctx->width >> 1);
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        V += s->frame.linesize[2] - (avctx->width >> 1);
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    }
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    *data_size=sizeof(AVFrame);
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    *(AVFrame*)data= s->frame;
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    return pkt->size;
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}
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static av_cold int aura_decode_end(AVCodecContext *avctx)
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{
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    AuraDecodeContext *s = avctx->priv_data;
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    if (s->frame.data[0])
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        avctx->release_buffer(avctx, &s->frame);
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    return 0;
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}
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AVCodec ff_aura2_decoder = {
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    "aura2",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_AURA2,
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    sizeof(AuraDecodeContext),
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    aura_decode_init,
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    NULL,
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    aura_decode_end,
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    aura_decode_frame,
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    CODEC_CAP_DR1,
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    NULL,
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    .long_name = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
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};
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