3 * Copyright (c) 2009 Stephen Backway
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * PGS subtitle decoder
28 #include "bytestream.h"
32 #include "libavutil/colorspace.h"
33 #include "libavutil/imgutils.h"
34 #include "libavutil/opt.h"
36 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
37 #define MAX_EPOCH_PALETTES 8 // Max 8 allowed per PGS epoch
38 #define MAX_EPOCH_OBJECTS 64 // Max 64 allowed per PGS epoch
39 #define MAX_OBJECT_REFS 2 // Max objects per display set
42 PALETTE_SEGMENT
= 0x14,
43 OBJECT_SEGMENT
= 0x15,
44 PRESENTATION_SEGMENT
= 0x16,
45 WINDOW_SEGMENT
= 0x17,
46 DISPLAY_SEGMENT
= 0x80,
49 typedef struct PGSSubObjectRef
{
52 uint8_t composition_flag
;
61 typedef struct PGSSubPresentation
{
65 PGSSubObjectRef objects
[MAX_OBJECT_REFS
];
69 typedef struct PGSSubObject
{
74 unsigned int rle_buffer_size
, rle_data_len
;
75 unsigned int rle_remaining_len
;
78 typedef struct PGSSubObjects
{
80 PGSSubObject object
[MAX_EPOCH_OBJECTS
];
83 typedef struct PGSSubPalette
{
88 typedef struct PGSSubPalettes
{
90 PGSSubPalette palette
[MAX_EPOCH_PALETTES
];
93 typedef struct PGSSubContext
{
95 PGSSubPresentation presentation
;
96 PGSSubPalettes palettes
;
97 PGSSubObjects objects
;
101 static void flush_cache(AVCodecContext
*avctx
)
103 PGSSubContext
*ctx
= avctx
->priv_data
;
106 for (i
= 0; i
< ctx
->objects
.count
; i
++) {
107 av_freep(&ctx
->objects
.object
[i
].rle
);
108 ctx
->objects
.object
[i
].rle_buffer_size
= 0;
109 ctx
->objects
.object
[i
].rle_remaining_len
= 0;
111 ctx
->objects
.count
= 0;
112 ctx
->palettes
.count
= 0;
115 static PGSSubObject
* find_object(int id
, PGSSubObjects
*objects
)
119 for (i
= 0; i
< objects
->count
; i
++) {
120 if (objects
->object
[i
].id
== id
)
121 return &objects
->object
[i
];
126 static PGSSubPalette
* find_palette(int id
, PGSSubPalettes
*palettes
)
130 for (i
= 0; i
< palettes
->count
; i
++) {
131 if (palettes
->palette
[i
].id
== id
)
132 return &palettes
->palette
[i
];
137 static av_cold
int init_decoder(AVCodecContext
*avctx
)
139 avctx
->pix_fmt
= AV_PIX_FMT_PAL8
;
144 static av_cold
int close_decoder(AVCodecContext
*avctx
)
152 * Decode the RLE data.
154 * The subtitle is stored as a Run Length Encoded image.
156 * @param avctx contains the current codec context
157 * @param sub pointer to the processed subtitle data
158 * @param buf pointer to the RLE data to process
159 * @param buf_size size of the RLE data to process
161 static int decode_rle(AVCodecContext
*avctx
, AVSubtitleRect
*rect
,
162 const uint8_t *buf
, unsigned int buf_size
)
164 const uint8_t *rle_bitmap_end
;
165 int pixel_count
, line_count
;
167 rle_bitmap_end
= buf
+ buf_size
;
169 rect
->pict
.data
[0] = av_malloc(rect
->w
* rect
->h
);
171 if (!rect
->pict
.data
[0])
172 return AVERROR(ENOMEM
);
177 while (buf
< rle_bitmap_end
&& line_count
< rect
->h
) {
178 uint8_t flags
, color
;
181 color
= bytestream_get_byte(&buf
);
185 flags
= bytestream_get_byte(&buf
);
188 run
= (run
<< 8) + bytestream_get_byte(&buf
);
189 color
= flags
& 0x80 ? bytestream_get_byte(&buf
) : 0;
192 if (run
> 0 && pixel_count
+ run
<= rect
->w
* rect
->h
) {
193 memset(rect
->pict
.data
[0] + pixel_count
, color
, run
);
197 * New Line. Check if correct pixels decoded, if not display warning
198 * and adjust bitmap pointer to correct new line position.
200 if (pixel_count
% rect
->w
> 0) {
201 av_log(avctx
, AV_LOG_ERROR
, "Decoded %d pixels, when line should be %d pixels\n",
202 pixel_count
% rect
->w
, rect
->w
);
203 if (avctx
->err_recognition
& AV_EF_EXPLODE
) {
204 return AVERROR_INVALIDDATA
;
211 if (pixel_count
< rect
->w
* rect
->h
) {
212 av_log(avctx
, AV_LOG_ERROR
, "Insufficient RLE data for subtitle\n");
213 return AVERROR_INVALIDDATA
;
216 av_dlog(avctx
, "Pixel Count = %d, Area = %d\n", pixel_count
, rect
->w
* rect
->h
);
222 * Parse the picture segment packet.
224 * The picture segment contains details on the sequence id,
225 * width, height and Run Length Encoded (RLE) bitmap data.
227 * @param avctx contains the current codec context
228 * @param buf pointer to the packet to process
229 * @param buf_size size of packet to process
231 static int parse_object_segment(AVCodecContext
*avctx
,
232 const uint8_t *buf
, int buf_size
)
234 PGSSubContext
*ctx
= avctx
->priv_data
;
235 PGSSubObject
*object
;
237 uint8_t sequence_desc
;
238 unsigned int rle_bitmap_len
, width
, height
;
242 return AVERROR_INVALIDDATA
;
245 id
= bytestream_get_be16(&buf
);
246 object
= find_object(id
, &ctx
->objects
);
248 if (ctx
->objects
.count
>= MAX_EPOCH_OBJECTS
) {
249 av_log(avctx
, AV_LOG_ERROR
, "Too many objects in epoch\n");
250 return AVERROR_INVALIDDATA
;
252 object
= &ctx
->objects
.object
[ctx
->objects
.count
++];
256 /* skip object version number */
259 /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
260 sequence_desc
= bytestream_get_byte(&buf
);
262 if (!(sequence_desc
& 0x80)) {
263 /* Additional RLE data */
264 if (buf_size
> object
->rle_remaining_len
)
265 return AVERROR_INVALIDDATA
;
267 memcpy(object
->rle
+ object
->rle_data_len
, buf
, buf_size
);
268 object
->rle_data_len
+= buf_size
;
269 object
->rle_remaining_len
-= buf_size
;
275 return AVERROR_INVALIDDATA
;
278 /* Decode rle bitmap length, stored size includes width/height data */
279 rle_bitmap_len
= bytestream_get_be24(&buf
) - 2*2;
281 if (buf_size
> rle_bitmap_len
) {
282 av_log(avctx
, AV_LOG_ERROR
,
283 "Buffer dimension %d larger than the expected RLE data %d\n",
284 buf_size
, rle_bitmap_len
);
285 return AVERROR_INVALIDDATA
;
288 /* Get bitmap dimensions from data */
289 width
= bytestream_get_be16(&buf
);
290 height
= bytestream_get_be16(&buf
);
292 /* Make sure the bitmap is not too large */
293 if (avctx
->width
< width
|| avctx
->height
< height
) {
294 av_log(avctx
, AV_LOG_ERROR
, "Bitmap dimensions larger than video.\n");
295 return AVERROR_INVALIDDATA
;
301 av_fast_padded_malloc(&object
->rle
, &object
->rle_buffer_size
, rle_bitmap_len
);
304 return AVERROR(ENOMEM
);
306 memcpy(object
->rle
, buf
, buf_size
);
307 object
->rle_data_len
= buf_size
;
308 object
->rle_remaining_len
= rle_bitmap_len
- buf_size
;
314 * Parse the palette segment packet.
316 * The palette segment contains details of the palette,
317 * a maximum of 256 colors can be defined.
319 * @param avctx contains the current codec context
320 * @param buf pointer to the packet to process
321 * @param buf_size size of packet to process
323 static int parse_palette_segment(AVCodecContext
*avctx
,
324 const uint8_t *buf
, int buf_size
)
326 PGSSubContext
*ctx
= avctx
->priv_data
;
327 PGSSubPalette
*palette
;
329 const uint8_t *buf_end
= buf
+ buf_size
;
330 const uint8_t *cm
= ff_crop_tab
+ MAX_NEG_CROP
;
332 int y
, cb
, cr
, alpha
;
333 int r
, g
, b
, r_add
, g_add
, b_add
;
336 id
= bytestream_get_byte(&buf
);
337 palette
= find_palette(id
, &ctx
->palettes
);
339 if (ctx
->palettes
.count
>= MAX_EPOCH_PALETTES
) {
340 av_log(avctx
, AV_LOG_ERROR
, "Too many palettes in epoch\n");
341 return AVERROR_INVALIDDATA
;
343 palette
= &ctx
->palettes
.palette
[ctx
->palettes
.count
++];
347 /* Skip palette version */
350 while (buf
< buf_end
) {
351 color_id
= bytestream_get_byte(&buf
);
352 y
= bytestream_get_byte(&buf
);
353 cr
= bytestream_get_byte(&buf
);
354 cb
= bytestream_get_byte(&buf
);
355 alpha
= bytestream_get_byte(&buf
);
358 YUV_TO_RGB2(r
, g
, b
, y
);
360 av_dlog(avctx
, "Color %d := (%d,%d,%d,%d)\n", color_id
, r
, g
, b
, alpha
);
362 /* Store color in palette */
363 palette
->clut
[color_id
] = RGBA(r
,g
,b
,alpha
);
369 * Parse the presentation segment packet.
371 * The presentation segment contains details on the video
372 * width, video height, x & y subtitle position.
374 * @param avctx contains the current codec context
375 * @param buf pointer to the packet to process
376 * @param buf_size size of packet to process
377 * @todo TODO: Implement cropping
379 static int parse_presentation_segment(AVCodecContext
*avctx
,
380 const uint8_t *buf
, int buf_size
,
383 PGSSubContext
*ctx
= avctx
->priv_data
;
385 const uint8_t *buf_end
= buf
+ buf_size
;
388 int w
= bytestream_get_be16(&buf
);
389 int h
= bytestream_get_be16(&buf
);
391 ctx
->presentation
.pts
= pts
;
393 av_dlog(avctx
, "Video Dimensions %dx%d\n",
395 ret
= ff_set_dimensions(avctx
, w
, h
);
399 /* Skip 1 bytes of unknown, frame rate */
402 // Composition descriptor
403 ctx
->presentation
.id_number
= bytestream_get_be16(&buf
);
405 * state is a 2 bit field that defines pgs epoch boundaries
406 * 00 - Normal, previously defined objects and palettes are still valid
407 * 01 - Acquisition point, previous objects and palettes can be released
408 * 10 - Epoch start, previous objects and palettes can be released
409 * 11 - Epoch continue, previous objects and palettes can be released
411 * reserved 6 bits discarded
413 state
= bytestream_get_byte(&buf
) >> 6;
419 * skip palette_update_flag (0x80),
422 ctx
->presentation
.palette_id
= bytestream_get_byte(&buf
);
423 ctx
->presentation
.object_count
= bytestream_get_byte(&buf
);
424 if (ctx
->presentation
.object_count
> MAX_OBJECT_REFS
) {
425 av_log(avctx
, AV_LOG_ERROR
,
426 "Invalid number of presentation objects %d\n",
427 ctx
->presentation
.object_count
);
428 ctx
->presentation
.object_count
= 2;
429 if (avctx
->err_recognition
& AV_EF_EXPLODE
) {
430 return AVERROR_INVALIDDATA
;
435 for (i
= 0; i
< ctx
->presentation
.object_count
; i
++)
438 if (buf_end
- buf
< 8) {
439 av_log(avctx
, AV_LOG_ERROR
, "Insufficent space for object\n");
440 ctx
->presentation
.object_count
= i
;
441 return AVERROR_INVALIDDATA
;
444 ctx
->presentation
.objects
[i
].id
= bytestream_get_be16(&buf
);
445 ctx
->presentation
.objects
[i
].window_id
= bytestream_get_byte(&buf
);
446 ctx
->presentation
.objects
[i
].composition_flag
= bytestream_get_byte(&buf
);
448 ctx
->presentation
.objects
[i
].x
= bytestream_get_be16(&buf
);
449 ctx
->presentation
.objects
[i
].y
= bytestream_get_be16(&buf
);
452 if (ctx
->presentation
.objects
[i
].composition_flag
& 0x80) {
453 ctx
->presentation
.objects
[i
].crop_x
= bytestream_get_be16(&buf
);
454 ctx
->presentation
.objects
[i
].crop_y
= bytestream_get_be16(&buf
);
455 ctx
->presentation
.objects
[i
].crop_w
= bytestream_get_be16(&buf
);
456 ctx
->presentation
.objects
[i
].crop_h
= bytestream_get_be16(&buf
);
459 av_dlog(avctx
, "Subtitle Placement x=%d, y=%d\n",
460 ctx
->presentation
.objects
[i
].x
, ctx
->presentation
.objects
[i
].y
);
462 if (ctx
->presentation
.objects
[i
].x
> avctx
->width
||
463 ctx
->presentation
.objects
[i
].y
> avctx
->height
) {
464 av_log(avctx
, AV_LOG_ERROR
, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
465 ctx
->presentation
.objects
[i
].x
,
466 ctx
->presentation
.objects
[i
].y
,
467 avctx
->width
, avctx
->height
);
468 ctx
->presentation
.objects
[i
].x
= 0;
469 ctx
->presentation
.objects
[i
].y
= 0;
470 if (avctx
->err_recognition
& AV_EF_EXPLODE
) {
471 return AVERROR_INVALIDDATA
;
480 * Parse the display segment packet.
482 * The display segment controls the updating of the display.
484 * @param avctx contains the current codec context
485 * @param data pointer to the data pertaining the subtitle to display
486 * @param buf pointer to the packet to process
487 * @param buf_size size of packet to process
489 static int display_end_segment(AVCodecContext
*avctx
, void *data
,
490 const uint8_t *buf
, int buf_size
)
492 AVSubtitle
*sub
= data
;
493 PGSSubContext
*ctx
= avctx
->priv_data
;
495 PGSSubPalette
*palette
;
498 pts
= ctx
->presentation
.pts
!= AV_NOPTS_VALUE
? ctx
->presentation
.pts
: sub
->pts
;
499 memset(sub
, 0, sizeof(*sub
));
501 ctx
->presentation
.pts
= AV_NOPTS_VALUE
;
502 sub
->start_display_time
= 0;
503 // There is no explicit end time for PGS subtitles. The end time
504 // is defined by the start of the next sub which may contain no
505 // objects (i.e. clears the previous sub)
506 sub
->end_display_time
= UINT32_MAX
;
509 // Blank if last object_count was 0.
510 if (!ctx
->presentation
.object_count
)
512 sub
->rects
= av_mallocz(sizeof(*sub
->rects
) * ctx
->presentation
.object_count
);
514 return AVERROR(ENOMEM
);
516 palette
= find_palette(ctx
->presentation
.palette_id
, &ctx
->palettes
);
518 // Missing palette. Should only happen with damaged streams.
519 av_log(avctx
, AV_LOG_ERROR
, "Invalid palette id %d\n",
520 ctx
->presentation
.palette_id
);
521 avsubtitle_free(sub
);
522 return AVERROR_INVALIDDATA
;
524 for (i
= 0; i
< ctx
->presentation
.object_count
; i
++) {
525 PGSSubObject
*object
;
527 sub
->rects
[i
] = av_mallocz(sizeof(*sub
->rects
[0]));
528 if (!sub
->rects
[i
]) {
529 avsubtitle_free(sub
);
530 return AVERROR(ENOMEM
);
533 sub
->rects
[i
]->type
= SUBTITLE_BITMAP
;
536 object
= find_object(ctx
->presentation
.objects
[i
].id
, &ctx
->objects
);
538 // Missing object. Should only happen with damaged streams.
539 av_log(avctx
, AV_LOG_ERROR
, "Invalid object id %d\n",
540 ctx
->presentation
.objects
[i
].id
);
541 if (avctx
->err_recognition
& AV_EF_EXPLODE
) {
542 avsubtitle_free(sub
);
543 return AVERROR_INVALIDDATA
;
545 // Leaves rect empty with 0 width and height.
548 if (ctx
->presentation
.objects
[i
].composition_flag
& 0x40)
549 sub
->rects
[i
]->flags
|= AV_SUBTITLE_FLAG_FORCED
;
551 sub
->rects
[i
]->x
= ctx
->presentation
.objects
[i
].x
;
552 sub
->rects
[i
]->y
= ctx
->presentation
.objects
[i
].y
;
553 sub
->rects
[i
]->w
= object
->w
;
554 sub
->rects
[i
]->h
= object
->h
;
556 sub
->rects
[i
]->pict
.linesize
[0] = object
->w
;
559 if (object
->rle_remaining_len
) {
560 av_log(avctx
, AV_LOG_ERROR
, "RLE data length %u is %u bytes shorter than expected\n",
561 object
->rle_data_len
, object
->rle_remaining_len
);
562 if (avctx
->err_recognition
& AV_EF_EXPLODE
) {
563 avsubtitle_free(sub
);
564 return AVERROR_INVALIDDATA
;
567 ret
= decode_rle(avctx
, sub
->rects
[i
], object
->rle
, object
->rle_data_len
);
569 if ((avctx
->err_recognition
& AV_EF_EXPLODE
) ||
570 ret
== AVERROR(ENOMEM
)) {
571 avsubtitle_free(sub
);
574 sub
->rects
[i
]->w
= 0;
575 sub
->rects
[i
]->h
= 0;
579 /* Allocate memory for colors */
580 sub
->rects
[i
]->nb_colors
= 256;
581 sub
->rects
[i
]->pict
.data
[1] = av_mallocz(AVPALETTE_SIZE
);
582 if (!sub
->rects
[i
]->pict
.data
[1]) {
583 avsubtitle_free(sub
);
584 return AVERROR(ENOMEM
);
587 if (!ctx
->forced_subs_only
|| ctx
->presentation
.objects
[i
].composition_flag
& 0x40)
588 memcpy(sub
->rects
[i
]->pict
.data
[1], palette
->clut
, sub
->rects
[i
]->nb_colors
* sizeof(uint32_t));
594 static int decode(AVCodecContext
*avctx
, void *data
, int *data_size
,
597 const uint8_t *buf
= avpkt
->data
;
598 int buf_size
= avpkt
->size
;
600 const uint8_t *buf_end
;
601 uint8_t segment_type
;
605 av_dlog(avctx
, "PGS sub packet:\n");
607 for (i
= 0; i
< buf_size
; i
++) {
608 av_dlog(avctx
, "%02x ", buf
[i
]);
610 av_dlog(avctx
, "\n");
614 av_dlog(avctx
, "\n");
618 /* Ensure that we have received at a least a segment code and segment length */
622 buf_end
= buf
+ buf_size
;
624 /* Step through buffer to identify segments */
625 while (buf
< buf_end
) {
626 segment_type
= bytestream_get_byte(&buf
);
627 segment_length
= bytestream_get_be16(&buf
);
629 av_dlog(avctx
, "Segment Length %d, Segment Type %x\n", segment_length
, segment_type
);
631 if (segment_type
!= DISPLAY_SEGMENT
&& segment_length
> buf_end
- buf
)
635 switch (segment_type
) {
636 case PALETTE_SEGMENT
:
637 ret
= parse_palette_segment(avctx
, buf
, segment_length
);
640 ret
= parse_object_segment(avctx
, buf
, segment_length
);
642 case PRESENTATION_SEGMENT
:
643 ret
= parse_presentation_segment(avctx
, buf
, segment_length
, ((AVSubtitle
*)(data
))->pts
);
647 * Window Segment Structure (No new information provided):
649 * 2 bytes: X position of subtitle,
650 * 2 bytes: Y position of subtitle,
651 * 2 bytes: Width of subtitle,
652 * 2 bytes: Height of subtitle.
655 case DISPLAY_SEGMENT
:
656 ret
= display_end_segment(avctx
, data
, buf
, segment_length
);
661 av_log(avctx
, AV_LOG_ERROR
, "Unknown subtitle segment type 0x%x, length %d\n",
662 segment_type
, segment_length
);
663 ret
= AVERROR_INVALIDDATA
;
666 if (ret
< 0 && (avctx
->err_recognition
& AV_EF_EXPLODE
))
669 buf
+= segment_length
;
675 #define OFFSET(x) offsetof(PGSSubContext, x)
676 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
677 static const AVOption options
[] = {
678 {"forced_subs_only", "Only show forced subtitles", OFFSET(forced_subs_only
), AV_OPT_TYPE_INT
, {.i64
= 0}, 0, 1, SD
},
682 static const AVClass pgsdec_class
= {
683 .class_name
= "PGS subtitle decoder",
684 .item_name
= av_default_item_name
,
686 .version
= LIBAVUTIL_VERSION_INT
,
689 AVCodec ff_pgssub_decoder
= {
691 .long_name
= NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
692 .type
= AVMEDIA_TYPE_SUBTITLE
,
693 .id
= AV_CODEC_ID_HDMV_PGS_SUBTITLE
,
694 .priv_data_size
= sizeof(PGSSubContext
),
695 .init
= init_decoder
,
696 .close
= close_decoder
,
698 .priv_class
= &pgsdec_class
,