aacenc.c

        for (i = 1; i <= s->chan_map[0]; i++) {
            avctx->bit_rate += s->chan_map[i] == TYPE_CPE ? 128000 : /* Pair */
                               s->chan_map[i] == TYPE_LFE ? 16000  : /* LFE  */
                                                            69000  ; /* SCE  */
        }
    }

    /* Samplerate */
    for (i = 0; i < 16; i++)
        if (avctx->sample_rate == avpriv_mpeg4audio_sample_rates[i])
            break;
    s->samplerate_index = i;
    ERROR_IF(s->samplerate_index == 16 ||
             s->samplerate_index >= ff_aac_swb_size_1024_len ||
             s->samplerate_index >= ff_aac_swb_size_128_len,
             "Unsupported sample rate %d\n", avctx->sample_rate);

    /* Bitrate limiting */
    WARN_IF(1024.0 * avctx->bit_rate / avctx->sample_rate > 6144 * s->channels,
             "Too many bits %f > %d per frame requested, clamping to max\n",
             1024.0 * avctx->bit_rate / avctx->sample_rate,
             6144 * s->channels);
    avctx->bit_rate = (int64_t)FFMIN(6144 * s->channels / 1024.0 * avctx->sample_rate,
                                     avctx->bit_rate);

    /* Profile and option setting */
    avctx->profile = avctx->profile == FF_PROFILE_UNKNOWN ? FF_PROFILE_AAC_LOW :
                     avctx->profile;
    for (i = 0; i < FF_ARRAY_ELEMS(aacenc_profiles); i++)
        if (avctx->profile == aacenc_profiles[i])
            break;
    if (avctx->profile == FF_PROFILE_MPEG2_AAC_LOW) {
        avctx->profile = FF_PROFILE_AAC_LOW;
        ERROR_IF(s->options.pred,
                 "Main prediction unavailable in the \"mpeg2_aac_low\" profile\n");
        ERROR_IF(s->options.ltp,
                 "LTP prediction unavailable in the \"mpeg2_aac_low\" profile\n");
        WARN_IF(s->options.pns,
                "PNS unavailable in the \"mpeg2_aac_low\" profile, turning off\n");
        s->options.pns = 0;
    } else if (avctx->profile == FF_PROFILE_AAC_LTP) {
        s->options.ltp = 1;
        ERROR_IF(s->options.pred,
                 "Main prediction unavailable in the \"aac_ltp\" profile\n");
    } else if (avctx->profile == FF_PROFILE_AAC_MAIN) {
        s->options.pred = 1;
        ERROR_IF(s->options.ltp,
                 "LTP prediction unavailable in the \"aac_main\" profile\n");
    } else if (s->options.ltp) {
        avctx->profile = FF_PROFILE_AAC_LTP;
        WARN_IF(1,
                "Chainging profile to \"aac_ltp\"\n");
        ERROR_IF(s->options.pred,
                 "Main prediction unavailable in the \"aac_ltp\" profile\n");
    } else if (s->options.pred) {
        avctx->profile = FF_PROFILE_AAC_MAIN;
        WARN_IF(1,
                "Chainging profile to \"aac_main\"\n");
        ERROR_IF(s->options.ltp,
                 "LTP prediction unavailable in the \"aac_main\" profile\n");
    }
    s->profile = avctx->profile;

    /* Coder limitations */
    s->coder = &ff_aac_coders[s->options.coder];
    if (s->options.coder == AAC_CODER_ANMR) {
        ERROR_IF(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL,
                 "The ANMR coder is considered experimental, add -strict -2 to enable!\n");
        s->options.intensity_stereo = 0;
        s->options.pns = 0;
    }
    ERROR_IF(s->options.ltp && avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL,
             "The LPT profile requires experimental compliance, add -strict -2 to enable!\n");

    /* M/S introduces horrible artifacts with multichannel files, this is temporary */
    if (s->channels > 3)
        s->options.mid_side = 0;

    if ((ret = dsp_init(avctx, s)) < 0)
        goto fail;

    if ((ret = alloc_buffers(avctx, s)) < 0)
        goto fail;

    if ((ret = put_audio_specific_config(avctx)))
        goto fail;

    sizes[0]   = ff_aac_swb_size_1024[s->samplerate_index];
    sizes[1]   = ff_aac_swb_size_128[s->samplerate_index];
    lengths[0] = ff_aac_num_swb_1024[s->samplerate_index];
    lengths[1] = ff_aac_num_swb_128[s->samplerate_index];
    for (i = 0; i < s->chan_map[0]; i++)
        grouping[i] = s->chan_map[i + 1] == TYPE_CPE;
    if ((ret = ff_psy_init(&s->psy, avctx, 2, sizes, lengths,
                           s->chan_map[0], grouping)) < 0)
        goto fail;
    s->psypp = ff_psy_preprocess_init(avctx);
    ff_lpc_init(&s->lpc, 2*avctx->frame_size, TNS_MAX_ORDER, FF_LPC_TYPE_LEVINSON);
    s->random_state = 0x1f2e3d4c;

    s->abs_pow34   = abs_pow34_v;
    s->quant_bands = quantize_bands;

    if (ARCH_X86)
        ff_aac_dsp_init_x86(s);

    if (HAVE_MIPSDSP)
        ff_aac_coder_init_mips(s);

    if ((ret = ff_thread_once(&aac_table_init, &aac_encode_init_tables)) != 0)
        return AVERROR_UNKNOWN;

    ff_af_queue_init(avctx, &s->afq);

    return 0;
fail:
    aac_encode_end(avctx);
    return ret;
}

#define AACENC_FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM
static const AVOption aacenc_options[] = {
    {"aac_coder", "Coding algorithm", offsetof(AACEncContext, options.coder), AV_OPT_TYPE_INT, {.i64 = AAC_CODER_FAST}, 0, AAC_CODER_NB-1, AACENC_FLAGS, "coder"},
        {"anmr",     "ANMR method",               0, AV_OPT_TYPE_CONST, {.i64 = AAC_CODER_ANMR},    INT_MIN, INT_MAX, AACENC_FLAGS, "coder"},
        {"twoloop",  "Two loop searching method", 0, AV_OPT_TYPE_CONST, {.i64 = AAC_CODER_TWOLOOP}, INT_MIN, INT_MAX, AACENC_FLAGS, "coder"},
        {"fast",     "Default fast search",       0, AV_OPT_TYPE_CONST, {.i64 = AAC_CODER_FAST},    INT_MIN, INT_MAX, AACENC_FLAGS, "coder"},
    {"aac_ms", "Force M/S stereo coding", offsetof(AACEncContext, options.mid_side), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, AACENC_FLAGS},
    {"aac_is", "Intensity stereo coding", offsetof(AACEncContext, options.intensity_stereo), AV_OPT_TYPE_BOOL, {.i64 = 1}, -1, 1, AACENC_FLAGS},
    {"aac_pns", "Perceptual noise substitution", offsetof(AACEncContext, options.pns), AV_OPT_TYPE_BOOL, {.i64 = 1}, -1, 1, AACENC_FLAGS},
    {"aac_tns", "Temporal noise shaping", offsetof(AACEncContext, options.tns), AV_OPT_TYPE_BOOL, {.i64 = 1}, -1, 1, AACENC_FLAGS},
    {"aac_ltp", "Long term prediction", offsetof(AACEncContext, options.ltp), AV_OPT_TYPE_BOOL, {.i64 = 0}, -1, 1, AACENC_FLAGS},
    {"aac_pred", "AAC-Main prediction", offsetof(AACEncContext, options.pred), AV_OPT_TYPE_BOOL, {.i64 = 0}, -1, 1, AACENC_FLAGS},
    {"aac_pce", "Forces the use of PCEs", offsetof(AACEncContext, options.pce), AV_OPT_TYPE_BOOL, {.i64 = 0}, -1, 1, AACENC_FLAGS},
    {NULL}
};

static const AVClass aacenc_class = {
    .class_name = "AAC encoder",
    .item_name  = av_default_item_name,
    .option     = aacenc_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

static const AVCodecDefault aac_encode_defaults[] = {
    { "b", "0" },
    { NULL }
};

AVCodec ff_aac_encoder = {
    .name           = "aac",
    .long_name      = NULL_IF_CONFIG_SMALL("AAC (Advanced Audio Coding)"),
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_AAC,
    .priv_data_size = sizeof(AACEncContext),
    .init           = aac_encode_init,
    .encode2        = aac_encode_frame,
    .close          = aac_encode_end,
    .defaults       = aac_encode_defaults,
    .supported_samplerates = mpeg4audio_sample_rates,
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
    .capabilities   = AV_CODEC_CAP_SMALL_LAST_FRAME | AV_CODEC_CAP_DELAY,
    .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
                                                     AV_SAMPLE_FMT_NONE },
    .priv_class     = &aacenc_class,
};