/*

 * Quicktime Animation (RLE) Video Encoder

 * Copyright (C) 2007 Clemens Fruhwirth

 * Copyright (C) 2007 Alexis Ballier

 *

 * This file is based on flashsvenc.c.

 *

 * 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/imgutils.h"

#include "libavutil/mem.h"

#include "avcodec.h"

#include "bytestream.h"

#include "codec_internal.h"

#include "encode.h"

/** Maximum RLE code for bulk copy */

#define MAX_RLE_BULK   127

/** Maximum RLE code for repeat */

#define MAX_RLE_REPEAT 128

/** Maximum RLE code for skip */

#define MAX_RLE_SKIP   254

typedef struct QtrleEncContext {

    AVCodecContext *avctx;

    int pixel_size;

    AVFrame *previous_frame;

    unsigned int max_buf_size;

    int logical_width;

    /**

     * This array will contain at ith position the value of the best RLE code

     * if the line started at pixel i

     * There can be 3 values :

     * skip (0)     : skip as much as possible pixels because they are equal to the

     *                previous frame ones

     * repeat (<-1) : repeat that pixel -rle_code times, still as much as

     *                possible

     * copy (>0)    : copy the raw next rle_code pixels */

    signed char *rlecode_table;

    /**

     * This array will contain the length of the best rle encoding of the line

     * starting at ith pixel */

    int *length_table;

    /**

     * Will contain at ith position the number of consecutive pixels equal to the previous

     * frame starting from pixel i */

    uint8_t* skip_table;

    /** Encoded frame is a key frame */

    int key_frame;

} QtrleEncContext;

static av_cold int qtrle_encode_end(AVCodecContext *avctx)

{

    QtrleEncContext *s = avctx->priv_data;

    av_frame_free(&s->previous_frame);

    av_free(s->rlecode_table);

    av_free(s->length_table);

    av_free(s->skip_table);

    return 0;

}

static av_cold int qtrle_encode_init(AVCodecContext *avctx)

{

    QtrleEncContext *s = avctx->priv_data;

    if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {

        return AVERROR(EINVAL);

    }

    s->avctx=avctx;

    s->logical_width=avctx->width;

    switch (avctx->pix_fmt) {

    case AV_PIX_FMT_GRAY8:

        if (avctx->width % 4) {

            av_log(avctx, AV_LOG_ERROR, "Width not being a multiple of 4 is not supported\n");

            return AVERROR(EINVAL);

        }

        s->logical_width = avctx->width / 4;

        s->pixel_size = 4;

        break;

    case AV_PIX_FMT_RGB555BE:

        s->pixel_size = 2;

        break;

    case AV_PIX_FMT_RGB24:

        s->pixel_size = 3;

        break;

    case AV_PIX_FMT_ARGB:

        s->pixel_size = 4;

        break;

    default:

        av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");

        break;

    }

    avctx->bits_per_coded_sample = avctx->pix_fmt == AV_PIX_FMT_GRAY8 ? 40 : s->pixel_size*8;

    s->rlecode_table = av_mallocz(s->logical_width);

    s->skip_table    = av_mallocz(s->logical_width);

    s->length_table  = av_calloc(s->logical_width + 1, sizeof(*s->length_table));

    if (!s->skip_table || !s->length_table || !s->rlecode_table) {

        av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");

        return AVERROR(ENOMEM);

    }

    s->previous_frame = av_frame_alloc();

    if (!s->previous_frame) {

        av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");

        return AVERROR(ENOMEM);

    }

    s->max_buf_size = s->logical_width*s->avctx->height*s->pixel_size*2 /* image base material */

                      + 15                                            /* header + footer */

                      + s->avctx->height*2                            /* skip code+rle end */

                      + s->logical_width/MAX_RLE_BULK + 1             /* rle codes */;

    return 0;

}

/**

 * Compute the best RLE sequence for a line

 */

static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)

{

    int width=s->logical_width;

    int i;

    signed char rlecode;

    /* This will be the number of pixels equal to the previous 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 av_uninit(repeatcount);

    /* The cost of the three different possibilities */

    int total_skip_cost;

    int total_repeat_cost;

    int base_bulk_cost;

    int lowest_bulk_cost;

    int lowest_bulk_cost_index;

    int sec_lowest_bulk_cost;

    int sec_lowest_bulk_cost_index;

    const uint8_t *this_line = p->data[0] + line * p->linesize[0] + width * s->pixel_size;

    /* There might be no earlier frame if the current frame is a keyframe.

     * So just use a pointer to the current frame to avoid a check

     * to avoid NULL - s->pixel_size (which is undefined behaviour). */

    const uint8_t *prev_line = s->key_frame ? this_line

                                            : s->previous_frame->data[0]

                                              + line * s->previous_frame->linesize[0]

                                              + width * s->pixel_size;

    s->length_table[width] = 0;

    skipcount = 0;

    /* Initial values */

    lowest_bulk_cost = INT_MAX / 2;

    lowest_bulk_cost_index = width;

    sec_lowest_bulk_cost = INT_MAX / 2;

    sec_lowest_bulk_cost_index = width;

    base_bulk_cost = 1 + s->pixel_size;

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

        int prev_bulk_cost;

        this_line -= s->pixel_size;

        prev_line -= s->pixel_size;

        /* If our lowest bulk cost index is too far away, replace it

         * with the next lowest bulk cost */

        if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {

            lowest_bulk_cost = sec_lowest_bulk_cost;

            lowest_bulk_cost_index = sec_lowest_bulk_cost_index;

            sec_lowest_bulk_cost = INT_MAX / 2;

            sec_lowest_bulk_cost_index = width;

        }

        /* Deal with the first pixel's bulk cost */

        if (!i) {

            base_bulk_cost++;

            lowest_bulk_cost++;

            sec_lowest_bulk_cost++;

        }

        /* Look at the bulk cost of the previous loop and see if it is

         * a new lower bulk cost */

        prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;

        if (prev_bulk_cost <= sec_lowest_bulk_cost) {

            /* If it's lower than the 2nd lowest, then it may be lower

             * than the lowest */

            if (prev_bulk_cost <= lowest_bulk_cost) {

                /* If we have found a new lowest bulk cost,

                 * then the 2nd lowest bulk cost is now farther than the

                 * lowest bulk cost, and will never be used */

                sec_lowest_bulk_cost = INT_MAX / 2;

                lowest_bulk_cost = prev_bulk_cost;

                lowest_bulk_cost_index = i + 1;

            } else {

                /* Then it must be the 2nd lowest bulk cost */

                sec_lowest_bulk_cost = prev_bulk_cost;

                sec_lowest_bulk_cost_index = i + 1;

            }

        }

        if (!s->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 use the best bulk copy  */

            s->length_table[i]  = lowest_bulk_cost;

            s->rlecode_table[i] = lowest_bulk_cost_index - i;

        }

        /* These bulk costs increase every iteration */

        lowest_bulk_cost += s->pixel_size;

        sec_lowest_bulk_cost += 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 == AV_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

                // AV_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 == AV_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

}

/** Encode frame including header */

static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)

{

    int i;

    int start_line = 0;

    int end_line = s->avctx->height;

    uint8_t *orig_buf = buf;

    if (!s->key_frame) {

        unsigned line_size = s->logical_width * s->pixel_size;

        for (start_line = 0; start_line < s->avctx->height; start_line++)

            if (memcmp(p->data[0] + start_line*p->linesize[0],

                       s->previous_frame->data[0] + start_line * s->previous_frame->linesize[0],

                       line_size))

                break;

        for (end_line=s->avctx->height; end_line > start_line; end_line--)

            if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],

                       s->previous_frame->data[0] + (end_line - 1) * s->previous_frame->linesize[0],

                       line_size))

                break;

    }

    bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later

    if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)

        bytestream_put_be16(&buf, 0);                     // header

    else {

        bytestream_put_be16(&buf, 8);                     // header

        bytestream_put_be16(&buf, start_line);            // starting line

        bytestream_put_be16(&buf, 0);                     // unknown

        bytestream_put_be16(&buf, end_line - start_line); // lines to update

        bytestream_put_be16(&buf, 0);                     // unknown

    }

    for (i = start_line; i < end_line; i++)

        qtrle_encode_line(s, p, i, &buf);

    bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished

    AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size

    return buf - orig_buf;

}

static int qtrle_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

                              const AVFrame *pict, int *got_packet)

{

    QtrleEncContext * const s = avctx->priv_data;

    int ret;

    if ((ret = ff_alloc_packet(avctx, pkt, s->max_buf_size)) < 0)

        return ret;

    if (avctx->gop_size == 0 || !s->previous_frame->data[0] ||

        (s->avctx->frame_num % avctx->gop_size) == 0) {

        /* I-Frame */

        s->key_frame = 1;

    } else {

        /* P-Frame */

        s->key_frame = 0;

    }

    pkt->size = encode_frame(s, pict, pkt->data);

    /* save the current frame */

    ret = av_frame_replace(s->previous_frame, pict);

    if (ret < 0) {

        av_log(avctx, AV_LOG_ERROR, "cannot add reference\n");

        return ret;

    }

    if (s->key_frame)

        pkt->flags |= AV_PKT_FLAG_KEY;

    *got_packet = 1;

    return 0;

}

const FFCodec ff_qtrle_encoder = {

    .p.name         = "qtrle",

    CODEC_LONG_NAME("QuickTime Animation (RLE) video"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_QTRLE,

    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,

    .priv_data_size = sizeof(QtrleEncContext),

    .init           = qtrle_encode_init,

    FF_CODEC_ENCODE_CB(qtrle_encode_frame),

    .close          = qtrle_encode_end,

    .p.pix_fmts     = (const enum AVPixelFormat[]){

        AV_PIX_FMT_RGB24, AV_PIX_FMT_RGB555BE, AV_PIX_FMT_ARGB, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE

    },

    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,

};