Function sonic_encode_frame

libavcodec/sonic.c:351–476

}

static int sonic_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
                              const AVFrame *frame, int *got_packet_ptr)
{
    SonicContext *s = avctx->priv_data;
    RangeCoder c;
    int i, j, ch, quant = 0, x = 0;
    int ret;
    const short *samples = (const int16_t*)frame->data[0];
    uint8_t state[32];

    if ((ret = ff_alloc_packet(avctx, avpkt, s->frame_size * 5 + 1000)) < 0)
        return ret;

    ff_init_range_encoder(&c, avpkt->data, avpkt->size);
    ff_build_rac_states(&c, 0.05*(1LL<<32), 256-8);
    memset(state, 128, sizeof(state));

    // short -> internal
    for (i = 0; i < s->frame_size; i++)
        s->int_samples[i] = samples[i];

    if (!s->lossless)
        for (i = 0; i < s->frame_size; i++)
            s->int_samples[i] = s->int_samples[i] << SAMPLE_SHIFT;

    switch(s->decorrelation)
    {
        case MID_SIDE:
            for (i = 0; i < s->frame_size; i += s->channels)
            {
                s->int_samples[i] += s->int_samples[i+1];
                s->int_samples[i+1] -= shift(s->int_samples[i], 1);
            }
            break;
        case LEFT_SIDE:
            for (i = 0; i < s->frame_size; i += s->channels)
                s->int_samples[i+1] -= s->int_samples[i];
            break;
        case RIGHT_SIDE:
            for (i = 0; i < s->frame_size; i += s->channels)
                s->int_samples[i] -= s->int_samples[i+1];
            break;
    }

    memset(s->window, 0, s->window_size * sizeof(*s->window));

    for (i = 0; i < s->tail_size; i++)
        s->window[x++] = s->tail[i];

    for (i = 0; i < s->frame_size; i++)
        s->window[x++] = s->int_samples[i];

    for (i = 0; i < s->tail_size; i++)
        s->window[x++] = 0;

    for (i = 0; i < s->tail_size; i++)
        s->tail[i] = s->int_samples[s->frame_size - s->tail_size + i];