FFmpeg
atsc_a53.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include <stddef.h>
20 #include <stdint.h>
21 
22 #include "atsc_a53.h"
23 #include "get_bits.h"
24 
25 int ff_alloc_a53_sei(const AVFrame *frame, size_t prefix_len,
26  void **data, size_t *sei_size)
27 {
28  AVFrameSideData *side_data = NULL;
29  uint8_t *sei_data;
30 
31  if (frame)
32  side_data = av_frame_get_side_data(frame, AV_FRAME_DATA_A53_CC);
33 
34  if (!side_data) {
35  *data = NULL;
36  return 0;
37  }
38 
39  *sei_size = side_data->size + 11;
40  *data = av_mallocz(*sei_size + prefix_len);
41  if (!*data)
42  return AVERROR(ENOMEM);
43  sei_data = (uint8_t*)*data + prefix_len;
44 
45  // country code
46  sei_data[0] = 181;
47  sei_data[1] = 0;
48  sei_data[2] = 49;
49 
50  /**
51  * 'GA94' is standard in North America for ATSC, but hard coding
52  * this style may not be the right thing to do -- other formats
53  * do exist. This information is not available in the side_data
54  * so we are going with this right now.
55  */
56  AV_WL32(sei_data + 3, MKTAG('G', 'A', '9', '4'));
57  sei_data[7] = 3;
58  sei_data[8] = ((side_data->size/3) & 0x1f) | 0x40;
59  sei_data[9] = 0;
60 
61  memcpy(sei_data + 10, side_data->data, side_data->size);
62 
63  sei_data[side_data->size+10] = 255;
64 
65  return 0;
66 }
67 
68 int ff_parse_a53_cc(AVBufferRef **pbuf, const uint8_t *data, int size)
69 {
70  AVBufferRef *buf = *pbuf;
71  GetBitContext gb;
72  size_t new_size, old_size = buf ? buf->size : 0;
73  int ret, cc_count;
74 
75  if (size < 3)
76  return AVERROR(EINVAL);
77 
78  ret = init_get_bits8(&gb, data, size);
79  if (ret < 0)
80  return ret;
81 
82  if (get_bits(&gb, 8) != 0x3) // user_data_type_code
83  return 0;
84 
85  skip_bits(&gb, 1); // reserved
86  if (!get_bits(&gb, 1)) // process_cc_data_flag
87  return 0;
88 
89  skip_bits(&gb, 1); // zero bit
90  cc_count = get_bits(&gb, 5);
91  if (!cc_count)
92  return 0;
93 
94  skip_bits(&gb, 8); // reserved
95 
96  /* 3 bytes per CC plus one byte marker_bits at the end */
97  if (cc_count * 3 >= (get_bits_left(&gb) >> 3))
98  return AVERROR(EINVAL);
99 
100  new_size = (old_size + cc_count * 3);
101 
102  if (new_size > INT_MAX)
103  return AVERROR(EINVAL);
104 
105  /* Allow merging of the cc data from two fields. */
106  ret = av_buffer_realloc(pbuf, new_size);
107  if (ret < 0)
108  return ret;
109 
110  buf = *pbuf;
111  /* Use of av_buffer_realloc assumes buffer is writeable */
112  for (int i = 0; i < cc_count; i++) {
113  buf->data[old_size++] = get_bits(&gb, 8);
114  buf->data[old_size++] = get_bits(&gb, 8);
115  buf->data[old_size++] = get_bits(&gb, 8);
116  }
117 
118  return cc_count;
119 }
#define NULL
Definition: coverity.c:32
This structure describes decoded (raw) audio or video data.
Definition: frame.h:308
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:237
AVFrameSideData * av_frame_get_side_data(const AVFrame *frame, enum AVFrameSideDataType type)
Definition: frame.c:738
uint8_t
int ff_parse_a53_cc(AVBufferRef **pbuf, const uint8_t *data, int size)
Parse a data array for ATSC A53 Part 4 Closed Captions and store them in an AVBufferRef.
Definition: atsc_a53.c:68
Structure to hold side data for an AVFrame.
Definition: frame.h:214
bitstream reader API header.
ptrdiff_t size
Definition: opengl_enc.c:100
int ff_alloc_a53_sei(const AVFrame *frame, size_t prefix_len, void **data, size_t *sei_size)
Check AVFrame for A53 side data and allocate and fill SEI message with A53 info.
Definition: atsc_a53.c:25
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
ATSC A53 Part 4 Closed Captions.
Definition: frame.h:58
int av_buffer_realloc(AVBufferRef **pbuf, int size)
Reallocate a given buffer.
Definition: buffer.c:169
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
uint8_t * data
The data buffer.
Definition: buffer.h:89
uint8_t * data
Definition: frame.h:216
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
int size
Size of data in bytes.
Definition: buffer.h:93
A reference to a data buffer.
Definition: buffer.h:81
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
#define MKTAG(a, b, c, d)
Definition: common.h:405
int i
Definition: input.c:407
#define AV_WL32(p, v)
Definition: intreadwrite.h:426