pafaudio.c

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/*
 * Packed Animation File audio decoder
 * Copyright (c) 2012 Paul B Mahol
 *
 * 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
 */

#include "libavutil/intreadwrite.h"

#include "avcodec.h"
#include "internal.h"
#include "mathops.h"

#define PAF_SOUND_SAMPLES     2205
#define PAF_SOUND_FRAME_SIZE  ((256 + PAF_SOUND_SAMPLES) * 2)

static av_cold int paf_audio_init(AVCodecContext *avctx)
{
    if (avctx->channels != 2) {
        av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
        return AVERROR_INVALIDDATA;
    }

    avctx->channel_layout = AV_CH_LAYOUT_STEREO;
    avctx->sample_fmt     = AV_SAMPLE_FMT_S16;

    return 0;
}

static int paf_audio_decode(AVCodecContext *avctx, void *data,
                            int *got_frame, AVPacket *pkt)
{
    AVFrame *frame = data;
    int16_t *output_samples;
    const uint8_t *src = pkt->data;
    int frames, ret, i, j;
    int16_t cb[256];

    frames = pkt->size / PAF_SOUND_FRAME_SIZE;
    if (frames < 1)
        return AVERROR_INVALIDDATA;

    frame->nb_samples = PAF_SOUND_SAMPLES * frames;
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;

    output_samples = (int16_t *)frame->data[0];
    // codebook of 256 16-bit samples and 8-bit indices to it
    for (j = 0; j < frames; j++) {
        for (i = 0; i < 256; i++)
            cb[i] = sign_extend(AV_RL16(src + i * 2), 16);
        src += 256 * 2;
        // always 2 channels
        for (i = 0; i < PAF_SOUND_SAMPLES * 2; i++)
            *output_samples++ = cb[*src++];
    }
    *got_frame = 1;

    return pkt->size;
}

AVCodec ff_paf_audio_decoder = {
    .name         = "paf_audio",
    .long_name    = NULL_IF_CONFIG_SMALL("Amazing Studio Packed Animation File Audio"),
    .type         = AVMEDIA_TYPE_AUDIO,
    .id           = AV_CODEC_ID_PAF_AUDIO,
    .init         = paf_audio_init,
    .decode       = paf_audio_decode,
    .capabilities = CODEC_CAP_DR1,
};