2 * Creative YUV (CYUV) Video Decoder
3 * by Mike Melanson (melanson@pcisys.net)
4 * based on "Creative YUV (CYUV) stream format for AVI":
5 * http://www.csse.monash.edu.au/~timf/videocodec/cyuv.txt
7 * Copyright (C) 2003 the ffmpeg project
9 * This file is part of FFmpeg.
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 * @file libavcodec/cyuv.c
28 * Creative YUV (CYUV) Video Decoder.
40 typedef struct CyuvDecodeContext {
41 AVCodecContext *avctx;
46 static av_cold int cyuv_decode_init(AVCodecContext *avctx)
48 CyuvDecodeContext *s = avctx->priv_data;
51 s->width = avctx->width;
52 /* width needs to be divisible by 4 for this codec to work */
55 s->height = avctx->height;
56 avctx->pix_fmt = PIX_FMT_YUV411P;
61 static int cyuv_decode_frame(AVCodecContext *avctx,
62 void *data, int *data_size,
65 const uint8_t *buf = avpkt->data;
66 int buf_size = avpkt->size;
67 CyuvDecodeContext *s=avctx->priv_data;
69 unsigned char *y_plane;
70 unsigned char *u_plane;
71 unsigned char *v_plane;
76 /* prediction error tables (make it clear that they are signed values) */
77 const signed char *y_table = (const signed char*)buf + 0;
78 const signed char *u_table = (const signed char*)buf + 16;
79 const signed char *v_table = (const signed char*)buf + 32;
81 unsigned char y_pred, u_pred, v_pred;
83 unsigned char cur_byte;
86 /* sanity check the buffer size: A buffer has 3x16-bytes tables
87 * followed by (height) lines each with 3 bytes to represent groups
88 * of 4 pixels. Thus, the total size of the buffer ought to be:
89 * (3 * 16) + height * (width * 3 / 4) */
90 if (buf_size != 48 + s->height * (s->width * 3 / 4)) {
91 av_log(avctx, AV_LOG_ERROR, "ffmpeg: cyuv: got a buffer with %d bytes when %d were expected\n",
93 48 + s->height * (s->width * 3 / 4));
97 /* pixel data starts 48 bytes in, after 3x16-byte tables */
101 avctx->release_buffer(avctx, &s->frame);
103 s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
104 s->frame.reference = 0;
105 if(avctx->get_buffer(avctx, &s->frame) < 0) {
106 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
110 y_plane = s->frame.data[0];
111 u_plane = s->frame.data[1];
112 v_plane = s->frame.data[2];
114 /* iterate through each line in the height */
115 for (y_ptr = 0, u_ptr = 0, v_ptr = 0;
116 y_ptr < (s->height * s->frame.linesize[0]);
117 y_ptr += s->frame.linesize[0] - s->width,
118 u_ptr += s->frame.linesize[1] - s->width / 4,
119 v_ptr += s->frame.linesize[2] - s->width / 4) {
121 /* reset predictors */
122 cur_byte = buf[stream_ptr++];
123 u_plane[u_ptr++] = u_pred = cur_byte & 0xF0;
124 y_plane[y_ptr++] = y_pred = (cur_byte & 0x0F) << 4;
126 cur_byte = buf[stream_ptr++];
127 v_plane[v_ptr++] = v_pred = cur_byte & 0xF0;
128 y_pred += y_table[cur_byte & 0x0F];
129 y_plane[y_ptr++] = y_pred;
131 cur_byte = buf[stream_ptr++];
132 y_pred += y_table[cur_byte & 0x0F];
133 y_plane[y_ptr++] = y_pred;
134 y_pred += y_table[(cur_byte & 0xF0) >> 4];
135 y_plane[y_ptr++] = y_pred;
137 /* iterate through the remaining pixel groups (4 pixels/group) */
138 pixel_groups = s->width / 4 - 1;
139 while (pixel_groups--) {
141 cur_byte = buf[stream_ptr++];
142 u_pred += u_table[(cur_byte & 0xF0) >> 4];
143 u_plane[u_ptr++] = u_pred;
144 y_pred += y_table[cur_byte & 0x0F];
145 y_plane[y_ptr++] = y_pred;
147 cur_byte = buf[stream_ptr++];
148 v_pred += v_table[(cur_byte & 0xF0) >> 4];
149 v_plane[v_ptr++] = v_pred;
150 y_pred += y_table[cur_byte & 0x0F];
151 y_plane[y_ptr++] = y_pred;
153 cur_byte = buf[stream_ptr++];
154 y_pred += y_table[cur_byte & 0x0F];
155 y_plane[y_ptr++] = y_pred;
156 y_pred += y_table[(cur_byte & 0xF0) >> 4];
157 y_plane[y_ptr++] = y_pred;
162 *data_size=sizeof(AVFrame);
163 *(AVFrame*)data= s->frame;
168 AVCodec cyuv_decoder = {
172 sizeof(CyuvDecodeContext),
179 .long_name = NULL_IF_CONFIG_SMALL("Creative YUV (CYUV)"),