1 |
|
|
/* |
2 |
|
|
* Bitstream filter for unpacking DivX-style packed B-frames in MPEG-4 (divx_packed) |
3 |
|
|
* Copyright (c) 2015 Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> |
4 |
|
|
* |
5 |
|
|
* This file is part of FFmpeg. |
6 |
|
|
* |
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. |
11 |
|
|
* |
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. |
16 |
|
|
* |
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 |
20 |
|
|
*/ |
21 |
|
|
|
22 |
|
|
#include "avcodec.h" |
23 |
|
|
#include "bsf.h" |
24 |
|
|
#include "internal.h" |
25 |
|
|
#include "mpeg4video.h" |
26 |
|
|
|
27 |
|
|
typedef struct UnpackBFramesBSFContext { |
28 |
|
|
AVBufferRef *b_frame_ref; |
29 |
|
|
} UnpackBFramesBSFContext; |
30 |
|
|
|
31 |
|
|
/* determine the position of the packed marker in the userdata, |
32 |
|
|
* the number of VOPs and the position of the second VOP */ |
33 |
|
16 |
static void scan_buffer(const uint8_t *buf, int buf_size, |
34 |
|
|
int *pos_p, int *nb_vop, int *pos_vop2) { |
35 |
|
|
uint32_t startcode; |
36 |
|
16 |
const uint8_t *end = buf + buf_size, *pos = buf; |
37 |
|
|
|
38 |
✓✓ |
64 |
while (pos < end) { |
39 |
|
48 |
startcode = -1; |
40 |
|
48 |
pos = avpriv_find_start_code(pos, end, &startcode); |
41 |
|
|
|
42 |
✓✓✓✗
|
48 |
if (startcode == USER_DATA_STARTCODE && pos_p) { |
43 |
|
|
/* check if the (DivX) userdata string ends with 'p' (packed) */ |
44 |
✓✓✓✓
|
290 |
for (int i = 0; i < 255 && pos + i + 1 < end; i++) { |
45 |
✓✓✓✓
|
286 |
if (pos[i] == 'p' && pos[i + 1] == '\0') { |
46 |
|
2 |
*pos_p = pos + i - buf; |
47 |
|
2 |
break; |
48 |
|
|
} |
49 |
|
|
} |
50 |
✓✓✓✗
|
44 |
} else if (startcode == VOP_STARTCODE && nb_vop) { |
51 |
|
20 |
*nb_vop += 1; |
52 |
✓✓✓✗
|
20 |
if (*nb_vop == 2 && pos_vop2) { |
53 |
|
5 |
*pos_vop2 = pos - buf - 4; /* subtract 4 bytes startcode */ |
54 |
|
|
} |
55 |
|
|
} |
56 |
|
|
} |
57 |
|
16 |
} |
58 |
|
|
|
59 |
|
30 |
static int mpeg4_unpack_bframes_filter(AVBSFContext *ctx, AVPacket *pkt) |
60 |
|
|
{ |
61 |
|
30 |
UnpackBFramesBSFContext *s = ctx->priv_data; |
62 |
|
30 |
int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0; |
63 |
|
|
|
64 |
|
30 |
ret = ff_bsf_get_packet_ref(ctx, pkt); |
65 |
✓✓ |
30 |
if (ret < 0) |
66 |
|
15 |
return ret; |
67 |
|
|
|
68 |
|
15 |
scan_buffer(pkt->data, pkt->size, &pos_p, &nb_vop, &pos_vop2); |
69 |
|
15 |
av_log(ctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop); |
70 |
|
|
|
71 |
✓✓ |
15 |
if (pos_vop2 >= 0) { |
72 |
✗✓ |
5 |
if (s->b_frame_ref) { |
73 |
|
|
av_log(ctx, AV_LOG_WARNING, |
74 |
|
|
"Missing one N-VOP packet, discarding one B-frame.\n"); |
75 |
|
|
av_buffer_unref(&s->b_frame_ref); |
76 |
|
|
} |
77 |
|
|
/* store a reference to the packed B-frame's data in the BSFContext */ |
78 |
|
5 |
s->b_frame_ref = av_buffer_ref(pkt->buf); |
79 |
✗✓ |
5 |
if (!s->b_frame_ref) { |
80 |
|
|
ret = AVERROR(ENOMEM); |
81 |
|
|
goto fail; |
82 |
|
|
} |
83 |
|
5 |
s->b_frame_ref->data = pkt->data + pos_vop2; |
84 |
|
5 |
s->b_frame_ref->size = pkt->size - pos_vop2; |
85 |
|
|
} |
86 |
|
|
|
87 |
✗✓ |
15 |
if (nb_vop > 2) { |
88 |
|
|
av_log(ctx, AV_LOG_WARNING, |
89 |
|
|
"Found %d VOP headers in one packet, only unpacking one.\n", nb_vop); |
90 |
|
|
} |
91 |
|
|
|
92 |
✓✓✓✓
|
22 |
if (nb_vop == 1 && s->b_frame_ref) { |
93 |
|
7 |
AVBufferRef *tmp = pkt->buf; |
94 |
|
|
|
95 |
|
|
/* make tmp accurately reflect the packet's data */ |
96 |
|
7 |
tmp->data = pkt->data; |
97 |
|
7 |
tmp->size = pkt->size; |
98 |
|
|
|
99 |
|
|
/* replace data in packet with stored data */ |
100 |
|
7 |
pkt->buf = s->b_frame_ref; |
101 |
|
7 |
pkt->data = s->b_frame_ref->data; |
102 |
|
7 |
pkt->size = s->b_frame_ref->size; |
103 |
|
|
|
104 |
|
|
/* store reference to data into BSFContext */ |
105 |
|
7 |
s->b_frame_ref = tmp; |
106 |
|
|
|
107 |
✓✓ |
7 |
if (s->b_frame_ref->size <= MAX_NVOP_SIZE) { |
108 |
|
|
/* N-VOP - discard stored data */ |
109 |
|
4 |
av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n"); |
110 |
|
4 |
av_buffer_unref(&s->b_frame_ref); |
111 |
|
|
} |
112 |
✓✓ |
8 |
} else if (nb_vop >= 2) { |
113 |
|
|
/* use first frame of the packet */ |
114 |
|
5 |
pkt->size = pos_vop2; |
115 |
✓✓ |
3 |
} else if (pos_p >= 0) { |
116 |
|
1 |
ret = av_packet_make_writable(pkt); |
117 |
✗✓ |
1 |
if (ret < 0) |
118 |
|
|
goto fail; |
119 |
|
1 |
av_log(ctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n"); |
120 |
|
|
/* remove 'p' (packed) from the end of the (DivX) userdata string */ |
121 |
|
1 |
pkt->data[pos_p] = '\0'; |
122 |
|
|
} else { |
123 |
|
|
/* use packet as is */ |
124 |
|
|
} |
125 |
|
|
|
126 |
|
2 |
fail: |
127 |
✗✓ |
15 |
if (ret < 0) |
128 |
|
|
av_packet_unref(pkt); |
129 |
|
|
|
130 |
|
15 |
return ret; |
131 |
|
|
} |
132 |
|
|
|
133 |
|
1 |
static int mpeg4_unpack_bframes_init(AVBSFContext *ctx) |
134 |
|
|
{ |
135 |
✓✗ |
1 |
if (ctx->par_in->extradata) { |
136 |
|
1 |
int pos_p_ext = -1; |
137 |
|
1 |
scan_buffer(ctx->par_in->extradata, ctx->par_in->extradata_size, &pos_p_ext, NULL, NULL); |
138 |
✓✗ |
1 |
if (pos_p_ext >= 0) { |
139 |
|
1 |
av_log(ctx, AV_LOG_DEBUG, |
140 |
|
|
"Updating DivX userdata (remove trailing 'p') in extradata.\n"); |
141 |
|
1 |
ctx->par_out->extradata[pos_p_ext] = '\0'; |
142 |
|
|
} |
143 |
|
|
} |
144 |
|
|
|
145 |
|
1 |
return 0; |
146 |
|
|
} |
147 |
|
|
|
148 |
|
1 |
static void mpeg4_unpack_bframes_close_flush(AVBSFContext *bsfc) |
149 |
|
|
{ |
150 |
|
1 |
UnpackBFramesBSFContext *ctx = bsfc->priv_data; |
151 |
|
1 |
av_buffer_unref(&ctx->b_frame_ref); |
152 |
|
1 |
} |
153 |
|
|
|
154 |
|
|
static const enum AVCodecID codec_ids[] = { |
155 |
|
|
AV_CODEC_ID_MPEG4, AV_CODEC_ID_NONE, |
156 |
|
|
}; |
157 |
|
|
|
158 |
|
|
const AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf = { |
159 |
|
|
.name = "mpeg4_unpack_bframes", |
160 |
|
|
.priv_data_size = sizeof(UnpackBFramesBSFContext), |
161 |
|
|
.init = mpeg4_unpack_bframes_init, |
162 |
|
|
.filter = mpeg4_unpack_bframes_filter, |
163 |
|
|
.flush = mpeg4_unpack_bframes_close_flush, |
164 |
|
|
.close = mpeg4_unpack_bframes_close_flush, |
165 |
|
|
.codec_ids = codec_ids, |
166 |
|
|
}; |