rl2 decoder

Originally committed as revision 12543 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 240 insertions, 0 deletions

diff --git a/libavcodec/rl2.c b/libavcodec/rl2.c
new file mode 100644
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+++ b/libavcodec/rl2.c
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+/*
+ * RL2 Video Decoder
+ * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
+ *
+ * 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
+ */
+
+/**
+ * RL2 Video Decoder
+ * @file rl2.c
+ * @author Sascha Sommer (saschasommer@freenet.de)
+ * For more information about the RL2 format, visit:
+ *   http://wiki.multimedia.cx/index.php?title=RL2
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "avcodec.h"
+
+
+#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
+
+typedef struct Rl2Context {
+    AVCodecContext *avctx;
+    AVFrame frame;
+
+    unsigned short video_base; ///< initial drawing offset
+    unsigned int clr_count;    ///< number of used colors (currently unused)
+    unsigned char* back_frame; ///< background frame
+    unsigned int palette[AVPALETTE_COUNT];
+} Rl2Context;
+
+/**
+ * Run Length Decode a single 320x200 frame
+ * @param s rl2 context
+ * @param buf input buffer
+ * @param size input buffer size
+ * @param out ouput buffer
+ * @param stride stride of the output buffer
+ * @param video_base offset of the rle data inside the frame
+ */
+static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
+                               unsigned char* out,int stride,int video_base){
+    int base_x = video_base % s->avctx->width;
+    int base_y = video_base / s->avctx->width;
+    int stride_adj = stride - s->avctx->width;
+    int i;
+    const unsigned char* back_frame = s->back_frame;
+    const unsigned char* in_end = in + size;
+    const unsigned char* out_end = out + stride * s->avctx->height;
+    unsigned char* line_end = out + s->avctx->width;
+
+    /** copy start of the background frame */
+    for(i=0;i<=base_y;i++){
+        if(s->back_frame)
+            memcpy(out,back_frame,s->avctx->width);
+        out += stride;
+        back_frame += s->avctx->width;
+    }
+    back_frame += base_x - s->avctx->width;
+    line_end = out - stride_adj;
+    out += base_x - stride;
+
+    /** decode the variable part of the frame */
+    while(in < in_end){
+        unsigned char val = *in++;
+        int len = 1;
+        if(val >= 0x80){
+            if(in >= in_end)
+                break;
+            len = *in++;
+            if(!len)
+                break;
+        }
+
+        if(len >= out_end - out)
+            break;
+
+        if(s->back_frame)
+            val |= 0x80;
+        else
+            val &= ~0x80;
+
+        while(len--){
+            *out++ = (val == 0x80)? *back_frame:val;
+            back_frame++;
+            if(out == line_end){
+                 out += stride_adj;
+                 line_end += stride;
+                 if(len >= out_end - out)
+                     break;
+            }
+        }
+    }
+
+    /** copy the rest from the background frame */
+    if(s->back_frame){
+        while(out < out_end){
+            memcpy(out, back_frame, line_end - out);
+            back_frame += line_end - out;
+            out = line_end + stride_adj;
+            line_end += stride;
+        }
+    }
+}
+
+
+/**
+ * Initialize the decoder
+ * @param avctx decoder context
+ * @return 0 success, -1 on error
+ */
+static av_cold int rl2_decode_init(AVCodecContext *avctx)
+{
+    Rl2Context *s = avctx->priv_data;
+    int back_size;
+    int i;
+    s->avctx = avctx;
+    avctx->pix_fmt = PIX_FMT_PAL8;
+
+    /** parse extra data */
+    if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
+        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
+        return -1;
+    }
+
+    /** get frame_offset */
+    s->video_base = AV_RL16(&avctx->extradata[0]);
+    s->clr_count = AV_RL32(&avctx->extradata[2]);
+
+    if(s->video_base >= avctx->width * avctx->height){
+        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
+        return -1;
+    }
+
+    /** initialize palette */
+    for(i=0;i<AVPALETTE_COUNT;i++)
+        s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
+
+    /** decode background frame if present */
+    back_size = avctx->extradata_size - EXTRADATA1_SIZE;
+
+    if(back_size > 0){
+        unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
+        if(!back_frame)
+            return -1;
+        rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
+                           back_frame,avctx->width,0);
+        s->back_frame = back_frame;
+    }
+    return 0;
+}
+
+
+/**
+ * Decode a single frame
+ * @param avctx decoder context
+ * @param data decoded frame
+ * @param data_size size of the decoded frame
+ * @param buf input buffer
+ * @param buf_size input buffer size
+ * @return 0 success, -1 on error
+ */
+static int rl2_decode_frame(AVCodecContext *avctx,
+                              void *data, int *data_size,
+                              const uint8_t *buf, int buf_size)
+{
+    Rl2Context *s = avctx->priv_data;
+
+    if(s->frame.data[0])
+        avctx->release_buffer(avctx, &s->frame);
+
+    /** get buffer */
+    s->frame.reference= 0;
+    if(avctx->get_buffer(avctx, &s->frame)) {
+        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return -1;
+    }
+
+    /** run length decode */
+    rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
+
+    /** make the palette available on the way out */
+    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame*)data = s->frame;
+
+    /** report that the buffer was completely consumed */
+    return buf_size;
+}
+
+
+/**
+ * Uninit decoder
+ * @param avctx decoder context
+ * @return 0 success, -1 on error
+ */
+static av_cold int rl2_decode_end(AVCodecContext *avctx)
+{
+    Rl2Context *s = avctx->priv_data;
+
+    if(s->frame.data[0])
+        avctx->release_buffer(avctx, &s->frame);
+
+    av_free(s->back_frame);
+
+    return 0;
+}
+
+
+AVCodec rl2_decoder = {
+    "rl2",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_RL2,
+    sizeof(Rl2Context),
+    rl2_decode_init,
+    NULL,
+    rl2_decode_end,
+    rl2_decode_frame,
+    CODEC_CAP_DR1,
+};
+