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1 /*
2  * Quicktime Animation (RLE) Video Encoder
3  * Copyright (C) 2007 Clemens Fruhwirth
4  * Copyright (C) 2007 Alexis Ballier
5  *
6  * This file is based on flashsvenc.c.
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "libavutil/imgutils.h"
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "codec_internal.h"
29 #include "encode.h"
30 
31 /** Maximum RLE code for bulk copy */
32 #define MAX_RLE_BULK   127
33 /** Maximum RLE code for repeat */
34 #define MAX_RLE_REPEAT 128
35 /** Maximum RLE code for skip */
36 #define MAX_RLE_SKIP   254
37 
38 typedef struct QtrleEncContext {
39     AVCodecContext *avctx;
40     int pixel_size;
41     AVFrame *previous_frame;
42     unsigned int max_buf_size;
43     int logical_width;
44     /**
45      * This array will contain at ith position the value of the best RLE code
46      * if the line started at pixel i
47      * There can be 3 values :
48      * skip (0)     : skip as much as possible pixels because they are equal to the
49      *                previous frame ones
50      * repeat (<-1) : repeat that pixel -rle_code times, still as much as
51      *                possible
52      * copy (>0)    : copy the raw next rle_code pixels */
53     signed char *rlecode_table;
54     /**
55      * This array will contain the length of the best rle encoding of the line
56      * starting at ith pixel */
57     int *length_table;
58     /**
59      * Will contain at ith position the number of consecutive pixels equal to the previous
60      * frame starting from pixel i */
61     uint8_t* skip_table;
62 
63     /** Encoded frame is a key frame */
64     int key_frame;
65 } QtrleEncContext;
66 
qtrle_encode_end(AVCodecContext * avctx)67 static av_cold int qtrle_encode_end(AVCodecContext *avctx)
68 {
69     QtrleEncContext *s = avctx->priv_data;
70 
71     av_frame_free(&s->previous_frame);
72     av_free(s->rlecode_table);
73     av_free(s->length_table);
74     av_free(s->skip_table);
75     return 0;
76 }
77 
qtrle_encode_init(AVCodecContext * avctx)78 static av_cold int qtrle_encode_init(AVCodecContext *avctx)
79 {
80     QtrleEncContext *s = avctx->priv_data;
81 
82     if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
83         return AVERROR(EINVAL);
84     }
85     s->avctx=avctx;
86     s->logical_width=avctx->width;
87 
88     switch (avctx->pix_fmt) {
89     case AV_PIX_FMT_GRAY8:
90         if (avctx->width % 4) {
91             av_log(avctx, AV_LOG_ERROR, "Width not being a multiple of 4 is not supported\n");
92             return AVERROR(EINVAL);
93         }
94         s->logical_width = avctx->width / 4;
95         s->pixel_size = 4;
96         break;
97     case AV_PIX_FMT_RGB555BE:
98         s->pixel_size = 2;
99         break;
100     case AV_PIX_FMT_RGB24:
101         s->pixel_size = 3;
102         break;
103     case AV_PIX_FMT_ARGB:
104         s->pixel_size = 4;
105         break;
106     default:
107         av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
108         break;
109     }
110     avctx->bits_per_coded_sample = avctx->pix_fmt == AV_PIX_FMT_GRAY8 ? 40 : s->pixel_size*8;
111 
112     s->rlecode_table = av_mallocz(s->logical_width);
113     s->skip_table    = av_mallocz(s->logical_width);
114     s->length_table  = av_calloc(s->logical_width + 1, sizeof(*s->length_table));
115     if (!s->skip_table || !s->length_table || !s->rlecode_table) {
116         av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
117         return AVERROR(ENOMEM);
118     }
119     s->previous_frame = av_frame_alloc();
120     if (!s->previous_frame) {
121         av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
122         return AVERROR(ENOMEM);
123     }
124 
125     s->max_buf_size = s->logical_width*s->avctx->height*s->pixel_size*2 /* image base material */
126                       + 15                                            /* header + footer */
127                       + s->avctx->height*2                            /* skip code+rle end */
128                       + s->logical_width/MAX_RLE_BULK + 1             /* rle codes */;
129 
130     return 0;
131 }
132 
133 /**
134  * Compute the best RLE sequence for a line
135  */
qtrle_encode_line(QtrleEncContext * s,const AVFrame * p,int line,uint8_t ** buf)136 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
137 {
138     int width=s->logical_width;
139     int i;
140     signed char rlecode;
141 
142     /* This will be the number of pixels equal to the previous frame one's
143      * starting from the ith pixel */
144     unsigned int skipcount;
145     /* This will be the number of consecutive equal pixels in the current
146      * frame, starting from the ith one also */
147     unsigned int av_uninit(repeatcount);
148 
149     /* The cost of the three different possibilities */
150     int total_skip_cost;
151     int total_repeat_cost;
152 
153     int base_bulk_cost;
154     int lowest_bulk_cost;
155     int lowest_bulk_cost_index;
156     int sec_lowest_bulk_cost;
157     int sec_lowest_bulk_cost_index;
158 
159     const uint8_t *this_line = p->data[0] + line * p->linesize[0] + width * s->pixel_size;
160     /* There might be no earlier frame if the current frame is a keyframe.
161      * So just use a pointer to the current frame to avoid a check
162      * to avoid NULL - s->pixel_size (which is undefined behaviour). */
163     const uint8_t *prev_line = s->key_frame ? this_line
164                                             : s->previous_frame->data[0]
165                                               + line * s->previous_frame->linesize[0]
166                                               + width * s->pixel_size;
167 
168     s->length_table[width] = 0;
169     skipcount = 0;
170 
171     /* Initial values */
172     lowest_bulk_cost = INT_MAX / 2;
173     lowest_bulk_cost_index = width;
174     sec_lowest_bulk_cost = INT_MAX / 2;
175     sec_lowest_bulk_cost_index = width;
176 
177     base_bulk_cost = 1 + s->pixel_size;
178 
179     for (i = width - 1; i >= 0; i--) {
180 
181         int prev_bulk_cost;
182 
183         this_line -= s->pixel_size;
184         prev_line -= s->pixel_size;
185 
186         /* If our lowest bulk cost index is too far away, replace it
187          * with the next lowest bulk cost */
188         if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {
189             lowest_bulk_cost = sec_lowest_bulk_cost;
190             lowest_bulk_cost_index = sec_lowest_bulk_cost_index;
191 
192             sec_lowest_bulk_cost = INT_MAX / 2;
193             sec_lowest_bulk_cost_index = width;
194         }
195 
196         /* Deal with the first pixel's bulk cost */
197         if (!i) {
198             base_bulk_cost++;
199             lowest_bulk_cost++;
200             sec_lowest_bulk_cost++;
201         }
202 
203         /* Look at the bulk cost of the previous loop and see if it is
204          * a new lower bulk cost */
205         prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;
206         if (prev_bulk_cost <= sec_lowest_bulk_cost) {
207             /* If it's lower than the 2nd lowest, then it may be lower
208              * than the lowest */
209             if (prev_bulk_cost <= lowest_bulk_cost) {
210 
211                 /* If we have found a new lowest bulk cost,
212                  * then the 2nd lowest bulk cost is now farther than the
213                  * lowest bulk cost, and will never be used */
214                 sec_lowest_bulk_cost = INT_MAX / 2;
215 
216                 lowest_bulk_cost = prev_bulk_cost;
217                 lowest_bulk_cost_index = i + 1;
218             } else {
219                 /* Then it must be the 2nd lowest bulk cost */
220                 sec_lowest_bulk_cost = prev_bulk_cost;
221                 sec_lowest_bulk_cost_index = i + 1;
222             }
223         }
224 
225         if (!s->key_frame && !memcmp(this_line, prev_line, s->pixel_size))
226             skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
227         else
228             skipcount = 0;
229 
230         total_skip_cost  = s->length_table[i + skipcount] + 2;
231         s->skip_table[i] = skipcount;
232 
233 
234         if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
235             repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
236         else
237             repeatcount = 1;
238 
239         total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
240 
241         /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
242          * so let's make it aware */
243         if (i == 0) {
244             total_skip_cost--;
245             total_repeat_cost++;
246         }
247 
248         if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
249             /* repeat is the best */
250             s->length_table[i]  = total_repeat_cost;
251             s->rlecode_table[i] = -repeatcount;
252         }
253         else if (skipcount > 0) {
254             /* skip is the best choice here */
255             s->length_table[i]  = total_skip_cost;
256             s->rlecode_table[i] = 0;
257         }
258         else {
259             /* We cannot do neither skip nor repeat
260              * thus we use the best bulk copy  */
261 
262             s->length_table[i]  = lowest_bulk_cost;
263             s->rlecode_table[i] = lowest_bulk_cost_index - i;
264 
265         }
266 
267         /* These bulk costs increase every iteration */
268         lowest_bulk_cost += s->pixel_size;
269         sec_lowest_bulk_cost += s->pixel_size;
270     }
271 
272     /* Good! Now we have the best sequence for this line, let's output it. */
273 
274     /* We do a special case for the first pixel so that we avoid testing it in
275      * the whole loop */
276 
277     i=0;
278     this_line = p->               data[0] + line*p->linesize[0];
279 
280     if (s->rlecode_table[0] == 0) {
281         bytestream_put_byte(buf, s->skip_table[0] + 1);
282         i += s->skip_table[0];
283     }
284     else bytestream_put_byte(buf, 1);
285 
286 
287     while (i < width) {
288         rlecode = s->rlecode_table[i];
289         bytestream_put_byte(buf, rlecode);
290         if (rlecode == 0) {
291             /* Write a skip sequence */
292             bytestream_put_byte(buf, s->skip_table[i] + 1);
293             i += s->skip_table[i];
294         }
295         else if (rlecode > 0) {
296             /* bulk copy */
297             if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
298                 int j;
299                 // QT grayscale colorspace has 0=white and 255=black, we will
300                 // ignore the palette that is included in the AVFrame because
301                 // AV_PIX_FMT_GRAY8 has defined color mapping
302                 for (j = 0; j < rlecode*s->pixel_size; ++j)
303                     bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
304             } else {
305                 bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
306             }
307             i += rlecode;
308         }
309         else {
310             /* repeat the bits */
311             if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
312                 int j;
313                 // QT grayscale colorspace has 0=white and 255=black, ...
314                 for (j = 0; j < s->pixel_size; ++j)
315                     bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
316             } else {
317                 bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
318             }
319             i -= rlecode;
320         }
321     }
322     bytestream_put_byte(buf, -1); // end RLE line
323 }
324 
325 /** Encode frame including header */
encode_frame(QtrleEncContext * s,const AVFrame * p,uint8_t * buf)326 static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
327 {
328     int i;
329     int start_line = 0;
330     int end_line = s->avctx->height;
331     uint8_t *orig_buf = buf;
332 
333     if (!s->key_frame) {
334         unsigned line_size = s->logical_width * s->pixel_size;
335         for (start_line = 0; start_line < s->avctx->height; start_line++)
336             if (memcmp(p->data[0] + start_line*p->linesize[0],
337                        s->previous_frame->data[0] + start_line * s->previous_frame->linesize[0],
338                        line_size))
339                 break;
340 
341         for (end_line=s->avctx->height; end_line > start_line; end_line--)
342             if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
343                        s->previous_frame->data[0] + (end_line - 1) * s->previous_frame->linesize[0],
344                        line_size))
345                 break;
346     }
347 
348     bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later
349 
350     if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
351         bytestream_put_be16(&buf, 0);                     // header
352     else {
353         bytestream_put_be16(&buf, 8);                     // header
354         bytestream_put_be16(&buf, start_line);            // starting line
355         bytestream_put_be16(&buf, 0);                     // unknown
356         bytestream_put_be16(&buf, end_line - start_line); // lines to update
357         bytestream_put_be16(&buf, 0);                     // unknown
358     }
359     for (i = start_line; i < end_line; i++)
360         qtrle_encode_line(s, p, i, &buf);
361 
362     bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished
363     AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size
364     return buf - orig_buf;
365 }
366 
qtrle_encode_frame(AVCodecContext * avctx,AVPacket * pkt,const AVFrame * pict,int * got_packet)367 static int qtrle_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
368                               const AVFrame *pict, int *got_packet)
369 {
370     QtrleEncContext * const s = avctx->priv_data;
371     int ret;
372 
373     if ((ret = ff_alloc_packet(avctx, pkt, s->max_buf_size)) < 0)
374         return ret;
375 
376     if (avctx->gop_size == 0 || !s->previous_frame->data[0] ||
377         (s->avctx->frame_number % avctx->gop_size) == 0) {
378         /* I-Frame */
379         s->key_frame = 1;
380     } else {
381         /* P-Frame */
382         s->key_frame = 0;
383     }
384 
385     pkt->size = encode_frame(s, pict, pkt->data);
386 
387     /* save the current frame */
388     av_frame_unref(s->previous_frame);
389     ret = av_frame_ref(s->previous_frame, pict);
390     if (ret < 0) {
391         av_log(avctx, AV_LOG_ERROR, "cannot add reference\n");
392         return ret;
393     }
394 
395     if (s->key_frame)
396         pkt->flags |= AV_PKT_FLAG_KEY;
397     *got_packet = 1;
398 
399     return 0;
400 }
401 
402 const FFCodec ff_qtrle_encoder = {
403     .p.name         = "qtrle",
404     .p.long_name    = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
405     .p.type         = AVMEDIA_TYPE_VIDEO,
406     .p.id           = AV_CODEC_ID_QTRLE,
407     .priv_data_size = sizeof(QtrleEncContext),
408     .init           = qtrle_encode_init,
409     FF_CODEC_ENCODE_CB(qtrle_encode_frame),
410     .close          = qtrle_encode_end,
411     .p.pix_fmts     = (const enum AVPixelFormat[]){
412         AV_PIX_FMT_RGB24, AV_PIX_FMT_RGB555BE, AV_PIX_FMT_ARGB, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE
413     },
414     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
415 };
416