PeerStreamer

/*

 * 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 "libavcore/imgutils.h"

#include "avcodec.h"

#include "bytestream.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;

    AVFrame frame;

    int pixel_size;

    AVPicture previous_frame;

    unsigned int max_buf_size;

    /**

     * 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;

} QtrleEncContext;

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 -1;

    }

    s->avctx=avctx;

    switch (avctx->pix_fmt) {

    case PIX_FMT_RGB555BE:

        s->pixel_size = 2;

        break;

    case PIX_FMT_RGB24:

        s->pixel_size = 3;

        break;

    case PIX_FMT_ARGB:

        s->pixel_size = 4;

        break;

    default:

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

        break;

    }

    avctx->bits_per_coded_sample = s->pixel_size*8;

    s->rlecode_table = av_mallocz(s->avctx->width);

    s->skip_table    = av_mallocz(s->avctx->width);

    s->length_table  = av_mallocz((s->avctx->width + 1)*sizeof(int));

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

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

        return -1;

    }

    if (avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height) < 0) {

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

        return -1;

    }

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

                      + 15                                           /* header + footer */

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

                      + s->avctx->width/MAX_RLE_BULK + 1             /* rle codes */;

    avctx->coded_frame = &s->frame;

    return 0;

}

/**

 * Compute the best RLE sequence for a line

 */

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

{

    int width=s->avctx->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 av_uninit(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 ouput 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 */

            bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);

            i += rlecode;

        }

        else {

            /* repeat the bits */

            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, AVFrame *p, uint8_t *buf)

{

    int i;

    int start_line = 0;

    int end_line = s->avctx->height;

    uint8_t *orig_buf = buf;

    if (!s->frame.key_frame) {

        unsigned line_size = s->avctx->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, uint8_t *buf, int buf_size, void *data)

{

    QtrleEncContext * const s = avctx->priv_data;

    AVFrame *pict = data;

    AVFrame * const p = &s->frame;

    int chunksize;

    *p = *pict;

    if (buf_size < s->max_buf_size) {

        /* Upper bound check for compressed data */

        av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->max_buf_size);

        return -1;

    }

    if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {

        /* I-Frame */

        p->pict_type = FF_I_TYPE;

        p->key_frame = 1;

    } else {

        /* P-Frame */

        p->pict_type = FF_P_TYPE;

        p->key_frame = 0;

    }

    chunksize = encode_frame(s, pict, buf);

    /* save the current frame */

    av_picture_copy(&s->previous_frame, (AVPicture *)p, avctx->pix_fmt, avctx->width, avctx->height);

    return chunksize;

}

static av_cold int qtrle_encode_end(AVCodecContext *avctx)

{

    QtrleEncContext *s = avctx->priv_data;

    avpicture_free(&s->previous_frame);

    av_free(s->rlecode_table);

    av_free(s->length_table);

    av_free(s->skip_table);

    return 0;

}

AVCodec ff_qtrle_encoder = {

    "qtrle",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_QTRLE,

    sizeof(QtrleEncContext),

    qtrle_encode_init,

    qtrle_encode_frame,

    qtrle_encode_end,

    .pix_fmts = (const enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGB555BE, PIX_FMT_ARGB, PIX_FMT_NONE},

    .long_name = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),

};