static void qtrle_encode_line(QtrleEncContext *s, AVFrame *p, int line, uint8_t **buf)
{
    int width=s->logical_width;
    int i;
    signed char rlecode;

    /* We will use it to compute the best bulk copy sequence */
    unsigned int bulkcount;
    /* This will be the number of pixels equal to the preivous frame one's
     * starting from the ith pixel */
    unsigned int skipcount;
    /* This will be the number of consecutive equal pixels in the current
     * frame, starting from the ith one also */
    unsigned int repeatcount;

    /* The cost of the three different possibilities */
    int total_bulk_cost;
    int total_skip_cost;
    int total_repeat_cost;

    int temp_cost;
    int j;

    uint8_t *this_line = p->               data[0] + line*p->               linesize[0] +
        (width - 1)*s->pixel_size;
    uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
        (width - 1)*s->pixel_size;

    s->length_table[width] = 0;
    skipcount = 0;

    for (i = width - 1; i >= 0; i--) {

        if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
            skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
        else
            skipcount = 0;

        total_skip_cost  = s->length_table[i + skipcount] + 2;
        s->skip_table[i] = skipcount;


        if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
            repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
        else
            repeatcount = 1;

        total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;

        /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
         * so let's make it aware */
        if (i == 0) {
            total_skip_cost--;
            total_repeat_cost++;
        }

        if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
            /* repeat is the best */
            s->length_table[i]  = total_repeat_cost;
            s->rlecode_table[i] = -repeatcount;
        }
        else if (skipcount > 0) {
            /* skip is the best choice here */
            s->length_table[i]  = total_skip_cost;
            s->rlecode_table[i] = 0;
        }
        else {
            /* We cannot do neither skip nor repeat
             * thus we search for the best bulk copy to do */

            int limit = FFMIN(width - i, MAX_RLE_BULK);

            temp_cost = 1 + s->pixel_size + !i;
            total_bulk_cost = INT_MAX;

            for (j = 1; j <= limit; j++) {
                if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
                    /* We have found a better bulk copy ... */
                    total_bulk_cost = s->length_table[i + j] + temp_cost;
                    bulkcount = j;
                }
                temp_cost += s->pixel_size;
            }

            s->length_table[i]  = total_bulk_cost;
            s->rlecode_table[i] = bulkcount;
        }

        this_line -= s->pixel_size;
        prev_line -= s->pixel_size;
    }

    /* Good ! Now we have the best sequence for this line, let's output it */

    /* We do a special case for the first pixel so that we avoid testing it in
     * the whole loop */

    i=0;
    this_line = p->               data[0] + line*p->linesize[0];

    if (s->rlecode_table[0] == 0) {
        bytestream_put_byte(buf, s->skip_table[0] + 1);
        i += s->skip_table[0];
    }
    else bytestream_put_byte(buf, 1);


    while (i < width) {
        rlecode = s->rlecode_table[i];
        bytestream_put_byte(buf, rlecode);
        if (rlecode == 0) {
            /* Write a skip sequence */
            bytestream_put_byte(buf, s->skip_table[i] + 1);
            i += s->skip_table[i];
        }
        else if (rlecode > 0) {
            /* bulk copy */
            if (s->avctx->pix_fmt == PIX_FMT_GRAY8) {
                int j;
                // QT grayscale colorspace has 0=white and 255=black, we will
                // ignore the palette that is included in the AVFrame because
                // PIX_FMT_GRAY8 has defined color mapping
                for (j = 0; j < rlecode*s->pixel_size; ++j)
                    bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
            } else {
                bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
            }
            i += rlecode;
        }
        else {
            /* repeat the bits */
            if (s->avctx->pix_fmt == PIX_FMT_GRAY8) {
                int j;
                // QT grayscale colorspace has 0=white and 255=black, ...
                for (j = 0; j < s->pixel_size; ++j)
                    bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
            } else {
                bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
            }
            i -= rlecode;
        }
    }
    bytestream_put_byte(buf, -1); // end RLE line
}