Function ff_vbv_update

libavcodec/ratecontrol.c:718–760

}

int ff_vbv_update(MPVMainEncContext *m, int frame_size)
{
    MPVEncContext      *const   s = &m->s;
    RateControlContext *const rcc = &m->rc_context;
    AVCodecContext   *const avctx = s->c.avctx;
    const double fps      = get_fps(avctx);
    const int buffer_size = avctx->rc_buffer_size;
    const double min_rate = avctx->rc_min_rate / fps;
    const double max_rate = avctx->rc_max_rate / fps;

    ff_dlog(avctx, "%d %f %d %f %f\n",
            buffer_size, rcc->buffer_index, frame_size, min_rate, max_rate);

    if (buffer_size) {
        int left;

        rcc->buffer_index -= frame_size;
        if (rcc->buffer_index < 0) {
            av_log(avctx, AV_LOG_ERROR, "rc buffer underflow\n");
            if (frame_size > max_rate && s->c.qscale == avctx->qmax) {
                av_log(avctx, AV_LOG_ERROR, "max bitrate possibly too small or try trellis with large lmax or increase qmax\n");
            }
            rcc->buffer_index = 0;
        }

        left = buffer_size - rcc->buffer_index - 1;
        rcc->buffer_index += av_clip(left, min_rate, max_rate);

        if (rcc->buffer_index > buffer_size) {
            int stuffing = ceil((rcc->buffer_index - buffer_size) / 8);

            if (stuffing < 4 && s->c.codec_id == AV_CODEC_ID_MPEG4)
                stuffing = 4;
            rcc->buffer_index -= 8 * stuffing;

            if (avctx->debug & FF_DEBUG_RC)
                av_log(avctx, AV_LOG_DEBUG, "stuffing %d bytes\n", stuffing);

            return stuffing;
        }
    }
    return 0;
}

static double predict_size(Predictor *p, double q, double var)
{