FFmpeg/libavcodec/vble.c

/*
 * VBLE Decoder
 * Copyright (c) 2011 Derek Buitenhuis
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * VBLE Decoder
 */

#define BITSTREAM_READER_LE

#include "avcodec.h"
#include "dsputil.h"
#include "get_bits.h"
#include "internal.h"
#include "mathops.h"

typedef struct {
    AVCodecContext *avctx;
    DSPContext dsp;

    int            size;
    uint8_t        *val; /* First holds the lengths of vlc symbols and then their values */
} VBLEContext;

static uint8_t vble_read_reverse_unary(GetBitContext *gb)
{
    /* At most we need to read 9 bits total to get indices up to 8 */
    uint8_t val = show_bits(gb, 8);

    if (val) {
        val = 7 - av_log2_16bit(ff_reverse[val]);
        skip_bits(gb, val + 1);
        return val;
    } else {
        skip_bits(gb, 8);
        if (get_bits1(gb))
            return 8;
    }

    /* Return something larger than 8 on error */
    return UINT8_MAX;
}

static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)
{
    int i;

    /* Read all the lengths in first */
    for (i = 0; i < ctx->size; i++) {
        ctx->val[i] = vble_read_reverse_unary(gb);

        if (ctx->val[i] == UINT8_MAX)
            return -1;
    }

    for (i = 0; i < ctx->size; i++) {
        /* Check we have enough bits left */
        if (get_bits_left(gb) < ctx->val[i])
            return -1;

        /* get_bits can't take a length of 0 */
        if (ctx->val[i])
            ctx->val[i] = (1 << ctx->val[i]) + get_bits(gb, ctx->val[i]) - 1;
    }

    return 0;
}

static void vble_restore_plane(VBLEContext *ctx, AVFrame *pic,
                               int plane, int offset,
                               int width, int height)
{
    uint8_t *dst = pic->data[plane];
    uint8_t *val = ctx->val + offset;
    int stride = pic->linesize[plane];
    int i, j, left, left_top;

    for (i = 0; i < height; i++) {
        for (j = 0; j < width; j++)
            val[j] = (val[j] >> 1) ^ -(val[j] & 1);

        if (i) {
            left = 0;
            left_top = dst[-stride];
            ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val,
                                                width, &left, &left_top);
        } else {
            dst[0] = val[0];
            for (j = 1; j < width; j++)
                dst[j] = val[j] + dst[j - 1];
        }
        dst += stride;
        val += width;
    }
}

static int vble_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                             AVPacket *avpkt)
{
    VBLEContext *ctx = avctx->priv_data;
    AVFrame *pic     = data;
    GetBitContext gb;
    const uint8_t *src = avpkt->data;
    int version;
    int offset = 0;
    int width_uv = avctx->width / 2, height_uv = avctx->height / 2;

    /* Allocate buffer */
    if (ff_get_buffer(avctx, pic, 0) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
        return AVERROR(ENOMEM);
    }

    /* Set flags */
    pic->key_frame = 1;
    pic->pict_type = AV_PICTURE_TYPE_I;

    /* Version should always be 1 */
    version = AV_RL32(src);

    if (version != 1)
        av_log(avctx, AV_LOG_WARNING, "Unsupported VBLE Version: %d\n", version);

    init_get_bits(&gb, src + 4, (avpkt->size - 4) * 8);

    /* Unpack */
    if (vble_unpack(ctx, &gb) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Invalid Code\n");
        return AVERROR_INVALIDDATA;
    }

    /* Restore planes. Should be almost identical to Huffyuv's. */
    vble_restore_plane(ctx, pic, 0, offset, avctx->width, avctx->height);

    /* Chroma */
    if (!(ctx->avctx->flags & CODEC_FLAG_GRAY)) {
        offset += avctx->width * avctx->height;
        vble_restore_plane(ctx, pic, 1, offset, width_uv, height_uv);

        offset += width_uv * height_uv;
        vble_restore_plane(ctx, pic, 2, offset, width_uv, height_uv);
    }

    *got_frame       = 1;

    return avpkt->size;
}

static av_cold int vble_decode_close(AVCodecContext *avctx)
{
    VBLEContext *ctx = avctx->priv_data;
    av_freep(&ctx->val);

    return 0;
}

static av_cold int vble_decode_init(AVCodecContext *avctx)
{
    VBLEContext *ctx = avctx->priv_data;

    /* Stash for later use */
    ctx->avctx = avctx;
    ff_dsputil_init(&ctx->dsp, avctx);

    avctx->pix_fmt = AV_PIX_FMT_YUV420P;
    avctx->bits_per_raw_sample = 8;

    ctx->size = avpicture_get_size(avctx->pix_fmt,
                                   avctx->width, avctx->height);

    ctx->val = av_malloc(ctx->size * sizeof(*ctx->val));

    if (!ctx->val) {
        av_log(avctx, AV_LOG_ERROR, "Could not allocate values buffer.\n");
        vble_decode_close(avctx);
        return AVERROR(ENOMEM);
    }

    return 0;
}

AVCodec ff_vble_decoder = {
    .name           = "vble",
    .long_name      = NULL_IF_CONFIG_SMALL("VBLE Lossless Codec"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_VBLE,
    .priv_data_size = sizeof(VBLEContext),
    .init           = vble_decode_init,
    .close          = vble_decode_close,
    .decode         = vble_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
};