libavcodec/vble.c
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00001 /*
00002  * VBLE Decoder
00003  * Copyright (c) 2011 Derek Buitenhuis
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #define BITSTREAM_READER_LE
00028 
00029 #include "avcodec.h"
00030 #include "dsputil.h"
00031 #include "get_bits.h"
00032 
00033 typedef struct {
00034     AVCodecContext *avctx;
00035     DSPContext dsp;
00036 
00037     int            size;
00038     uint8_t        *val; /* First holds the lengths of vlc symbols and then their values */
00039 } VBLEContext;
00040 
00041 static uint8_t vble_read_reverse_unary(GetBitContext *gb)
00042 {
00043     /* At most we need to read 9 bits total to get indices up to 8 */
00044     uint8_t val = show_bits(gb, 8);
00045 
00046     if (val) {
00047         val = 7 - av_log2_16bit(av_reverse[val]);
00048         skip_bits(gb, val + 1);
00049         return val;
00050     } else {
00051         skip_bits(gb, 8);
00052         if (get_bits1(gb))
00053             return 8;
00054     }
00055 
00056     /* Return something larger than 8 on error */
00057     return UINT8_MAX;
00058 }
00059 
00060 static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)
00061 {
00062     int i;
00063 
00064     /* Read all the lengths in first */
00065     for (i = 0; i < ctx->size; i++) {
00066         ctx->val[i] = vble_read_reverse_unary(gb);
00067 
00068         if (ctx->val[i] == UINT8_MAX)
00069             return -1;
00070     }
00071 
00072     for (i = 0; i < ctx->size; i++) {
00073         /* Check we have enough bits left */
00074         if (get_bits_left(gb) < ctx->val[i])
00075             return -1;
00076 
00077         /* get_bits can't take a length of 0 */
00078         if (ctx->val[i])
00079             ctx->val[i] = (1 << ctx->val[i]) + get_bits(gb, ctx->val[i]) - 1;
00080     }
00081 
00082     return 0;
00083 }
00084 
00085 static void vble_restore_plane(VBLEContext *ctx, int plane, int offset,
00086                               int width, int height)
00087 {
00088     AVFrame *pic = ctx->avctx->coded_frame;
00089     uint8_t *dst = pic->data[plane];
00090     uint8_t *val = ctx->val + offset;
00091     int stride = pic->linesize[plane];
00092     int i, j, left, left_top;
00093 
00094     for (i = 0; i < height; i++) {
00095         for (j = 0; j < width; j++)
00096             val[j] = (val[j] >> 1) ^ -(val[j] & 1);
00097 
00098         if (i) {
00099             left = 0;
00100             left_top = dst[-stride];
00101             ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val,
00102                                                 width, &left, &left_top);
00103         } else {
00104             dst[0] = val[0];
00105             for (j = 1; j < width; j++)
00106                 dst[j] = val[j] + dst[j - 1];
00107         }
00108         dst += stride;
00109         val += width;
00110     }
00111 }
00112 
00113 static int vble_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
00114                              AVPacket *avpkt)
00115 {
00116     VBLEContext *ctx = avctx->priv_data;
00117     AVFrame *pic = avctx->coded_frame;
00118     GetBitContext gb;
00119     const uint8_t *src = avpkt->data;
00120     int version;
00121     int offset = 0;
00122     int width_uv = avctx->width / 2, height_uv = avctx->height / 2;
00123 
00124     pic->reference = 0;
00125 
00126     /* Clear buffer if need be */
00127     if (pic->data[0])
00128         avctx->release_buffer(avctx, pic);
00129 
00130     /* Allocate buffer */
00131     if (avctx->get_buffer(avctx, pic) < 0) {
00132         av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
00133         return AVERROR(ENOMEM);
00134     }
00135 
00136     /* Set flags */
00137     pic->key_frame = 1;
00138     pic->pict_type = AV_PICTURE_TYPE_I;
00139 
00140     /* Version should always be 1 */
00141     version = AV_RL32(src);
00142 
00143     if (version != 1) {
00144         av_log(avctx, AV_LOG_ERROR, "Unsupported VBLE Version: %d\n", version);
00145         return AVERROR_INVALIDDATA;
00146     }
00147 
00148     init_get_bits(&gb, src + 4, (avpkt->size - 4) * 8);
00149 
00150     /* Unpack */
00151     if (vble_unpack(ctx, &gb) < 0) {
00152         av_log(avctx, AV_LOG_ERROR, "Invalid Code\n");
00153         return AVERROR_INVALIDDATA;
00154     }
00155 
00156     /* Restore planes. Should be almost identical to Huffyuv's. */
00157     vble_restore_plane(ctx, 0, offset, avctx->width, avctx->height);
00158 
00159     /* Chroma */
00160     if (!(ctx->avctx->flags & CODEC_FLAG_GRAY)) {
00161         offset += avctx->width * avctx->height;
00162         vble_restore_plane(ctx, 1, offset, width_uv, height_uv);
00163 
00164         offset += width_uv * height_uv;
00165         vble_restore_plane(ctx, 2, offset, width_uv, height_uv);
00166     }
00167 
00168     *data_size = sizeof(AVFrame);
00169     *(AVFrame *)data = *pic;
00170 
00171     return avpkt->size;
00172 }
00173 
00174 static av_cold int vble_decode_close(AVCodecContext *avctx)
00175 {
00176     VBLEContext *ctx = avctx->priv_data;
00177     AVFrame *pic = avctx->coded_frame;
00178 
00179     if (pic->data[0])
00180         avctx->release_buffer(avctx, pic);
00181 
00182     av_freep(&avctx->coded_frame);
00183     av_freep(&ctx->val);
00184 
00185     return 0;
00186 }
00187 
00188 static av_cold int vble_decode_init(AVCodecContext *avctx)
00189 {
00190     VBLEContext *ctx = avctx->priv_data;
00191 
00192     /* Stash for later use */
00193     ctx->avctx = avctx;
00194     dsputil_init(&ctx->dsp, avctx);
00195 
00196     avctx->pix_fmt = PIX_FMT_YUV420P;
00197     avctx->bits_per_raw_sample = 8;
00198     avctx->coded_frame = avcodec_alloc_frame();
00199 
00200     if (!avctx->coded_frame) {
00201         av_log(avctx, AV_LOG_ERROR, "Could not allocate frame.\n");
00202         return AVERROR(ENOMEM);
00203     }
00204 
00205     ctx->size = avpicture_get_size(avctx->pix_fmt,
00206                                    avctx->width, avctx->height);
00207 
00208     ctx->val = av_malloc(ctx->size * sizeof(*ctx->val));
00209 
00210     if (!ctx->val) {
00211         av_log(avctx, AV_LOG_ERROR, "Could not allocate values buffer.\n");
00212         vble_decode_close(avctx);
00213         return AVERROR(ENOMEM);
00214     }
00215 
00216     return 0;
00217 }
00218 
00219 AVCodec ff_vble_decoder = {
00220     .name           = "vble",
00221     .type           = AVMEDIA_TYPE_VIDEO,
00222     .id             = CODEC_ID_VBLE,
00223     .priv_data_size = sizeof(VBLEContext),
00224     .init           = vble_decode_init,
00225     .close          = vble_decode_close,
00226     .decode         = vble_decode_frame,
00227     .capabilities   = CODEC_CAP_DR1,
00228     .long_name      = NULL_IF_CONFIG_SMALL("VBLE Lossless Codec"),
00229 };