FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
movenccenc.c
Go to the documentation of this file.
1 /*
2  * MOV CENC (Common Encryption) writer
3  * Copyright (c) 2015 Eran Kornblau <erankor at gmail dot 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 #include "movenccenc.h"
22 #include "libavutil/intreadwrite.h"
23 #include "avio_internal.h"
24 #include "movenc.h"
25 #include "avc.h"
26 
28 {
29  size_t new_alloc_size;
30 
31  if (ctx->auxiliary_info_size + size > ctx->auxiliary_info_alloc_size) {
32  new_alloc_size = FFMAX(ctx->auxiliary_info_size + size, ctx->auxiliary_info_alloc_size * 2);
33  if (av_reallocp(&ctx->auxiliary_info, new_alloc_size)) {
34  return AVERROR(ENOMEM);
35  }
36 
37  ctx->auxiliary_info_alloc_size = new_alloc_size;
38  }
39 
40  return 0;
41 }
42 
44  const uint8_t *buf_in, int size)
45 {
46  int ret;
47 
48  ret = auxiliary_info_alloc_size(ctx, size);
49  if (ret) {
50  return ret;
51  }
52  memcpy(ctx->auxiliary_info + ctx->auxiliary_info_size, buf_in, size);
53  ctx->auxiliary_info_size += size;
54 
55  return 0;
56 }
57 
59  uint16_t clear_bytes, uint32_t encrypted_bytes)
60 {
61  uint8_t* p;
62  int ret;
63 
64  if (!ctx->use_subsamples) {
65  return 0;
66  }
67 
68  ret = auxiliary_info_alloc_size(ctx, 6);
69  if (ret) {
70  return ret;
71  }
72 
73  p = ctx->auxiliary_info + ctx->auxiliary_info_size;
74 
75  AV_WB16(p, clear_bytes);
76  p += sizeof(uint16_t);
77 
78  AV_WB32(p, encrypted_bytes);
79 
80  ctx->auxiliary_info_size += 6;
81  ctx->subsample_count++;
82 
83  return 0;
84 }
85 
86 /**
87  * Encrypt the input buffer and write using avio_write
88  */
90  const uint8_t *buf_in, int size)
91 {
92  uint8_t chunk[4096];
93  const uint8_t* cur_pos = buf_in;
94  int size_left = size;
95  int cur_size;
96 
97  while (size_left > 0) {
98  cur_size = FFMIN(size_left, sizeof(chunk));
99  av_aes_ctr_crypt(ctx->aes_ctr, chunk, cur_pos, cur_size);
100  avio_write(pb, chunk, cur_size);
101  cur_pos += cur_size;
102  size_left -= cur_size;
103  }
104 }
105 
106 /**
107  * Start writing a packet
108  */
110 {
111  int ret;
112 
113  /* write the iv */
115  if (ret) {
116  return ret;
117  }
118 
119  if (!ctx->use_subsamples) {
120  return 0;
121  }
122 
123  /* write a zero subsample count */
125  ctx->subsample_count = 0;
126  ret = auxiliary_info_write(ctx, (uint8_t*)&ctx->subsample_count, sizeof(ctx->subsample_count));
127  if (ret) {
128  return ret;
129  }
130 
131  return 0;
132 }
133 
134 /**
135  * Finalize a packet
136  */
138 {
139  size_t new_alloc_size;
140 
142 
143  if (!ctx->use_subsamples) {
144  ctx->auxiliary_info_entries++;
145  return 0;
146  }
147 
148  /* add the auxiliary info entry size*/
150  new_alloc_size = ctx->auxiliary_info_entries * 2 + 1;
151  if (av_reallocp(&ctx->auxiliary_info_sizes, new_alloc_size)) {
152  return AVERROR(ENOMEM);
153  }
154 
155  ctx->auxiliary_info_sizes_alloc_size = new_alloc_size;
156  }
159  ctx->auxiliary_info_entries++;
160 
161  /* update the subsample count*/
163 
164  return 0;
165 }
166 
168  const uint8_t *buf_in, int size)
169 {
170  int ret;
171 
172  ret = mov_cenc_start_packet(ctx);
173  if (ret) {
174  return ret;
175  }
176 
177  ret = auxiliary_info_add_subsample(ctx, 0, size);
178  if (ret) {
179  return ret;
180  }
181 
182  mov_cenc_write_encrypted(ctx, pb, buf_in, size);
183 
184  ret = mov_cenc_end_packet(ctx);
185  if (ret) {
186  return ret;
187  }
188 
189  return 0;
190 }
191 
193  const uint8_t *buf_in, int size)
194 {
195  const uint8_t *p = buf_in;
196  const uint8_t *end = p + size;
197  const uint8_t *nal_start, *nal_end;
198  int ret;
199 
200  ret = mov_cenc_start_packet(ctx);
201  if (ret) {
202  return ret;
203  }
204 
205  size = 0;
206  nal_start = ff_avc_find_startcode(p, end);
207  for (;;) {
208  while (nal_start < end && !*(nal_start++));
209  if (nal_start == end)
210  break;
211 
212  nal_end = ff_avc_find_startcode(nal_start, end);
213 
214  avio_wb32(pb, nal_end - nal_start);
215  avio_w8(pb, *nal_start);
216  mov_cenc_write_encrypted(ctx, pb, nal_start + 1, nal_end - nal_start - 1);
217 
218  auxiliary_info_add_subsample(ctx, 5, nal_end - nal_start - 1);
219 
220  size += 4 + nal_end - nal_start;
221  nal_start = nal_end;
222  }
223 
224  ret = mov_cenc_end_packet(ctx);
225  if (ret) {
226  return ret;
227  }
228 
229  return size;
230 }
231 
233  int nal_length_size, AVIOContext *pb, const uint8_t *buf_in, int size)
234 {
235  int nalsize;
236  int ret;
237  int j;
238 
239  ret = mov_cenc_start_packet(ctx);
240  if (ret) {
241  return ret;
242  }
243 
244  while (size > 0) {
245  /* parse the nal size */
246  if (size < nal_length_size + 1) {
247  av_log(s, AV_LOG_ERROR, "CENC-AVC: remaining size %d smaller than nal length+type %d\n",
248  size, nal_length_size + 1);
249  return -1;
250  }
251 
252  avio_write(pb, buf_in, nal_length_size + 1);
253 
254  nalsize = 0;
255  for (j = 0; j < nal_length_size; j++) {
256  nalsize = (nalsize << 8) | *buf_in++;
257  }
258  size -= nal_length_size;
259 
260  /* encrypt the nal body */
261  if (nalsize <= 0 || nalsize > size) {
262  av_log(s, AV_LOG_ERROR, "CENC-AVC: nal size %d remaining %d\n", nalsize, size);
263  return -1;
264  }
265 
266  mov_cenc_write_encrypted(ctx, pb, buf_in + 1, nalsize - 1);
267  buf_in += nalsize;
268  size -= nalsize;
269 
270  auxiliary_info_add_subsample(ctx, nal_length_size + 1, nalsize - 1);
271  }
272 
273  ret = mov_cenc_end_packet(ctx);
274  if (ret) {
275  return ret;
276  }
277 
278  return 0;
279 }
280 
281 /* TODO: reuse this function from movenc.c */
282 static int64_t update_size(AVIOContext *pb, int64_t pos)
283 {
284  int64_t curpos = avio_tell(pb);
285  avio_seek(pb, pos, SEEK_SET);
286  avio_wb32(pb, curpos - pos); /* rewrite size */
287  avio_seek(pb, curpos, SEEK_SET);
288 
289  return curpos - pos;
290 }
291 
293  int64_t* auxiliary_info_offset)
294 {
295  int64_t pos = avio_tell(pb);
296 
297  avio_wb32(pb, 0); /* size */
298  ffio_wfourcc(pb, "senc");
299  avio_wb32(pb, ctx->use_subsamples ? 0x02 : 0); /* version & flags */
300  avio_wb32(pb, ctx->auxiliary_info_entries); /* entry count */
301  *auxiliary_info_offset = avio_tell(pb);
303  return update_size(pb, pos);
304 }
305 
306 static int mov_cenc_write_saio_tag(AVIOContext *pb, int64_t auxiliary_info_offset)
307 {
308  int64_t pos = avio_tell(pb);
310 
311  avio_wb32(pb, 0); /* size */
312  ffio_wfourcc(pb, "saio");
313  version = auxiliary_info_offset > 0xffffffff ? 1 : 0;
314  avio_w8(pb, version);
315  avio_wb24(pb, 0); /* flags */
316  avio_wb32(pb, 1); /* entry count */
317  if (version) {
318  avio_wb64(pb, auxiliary_info_offset);
319  } else {
320  avio_wb32(pb, auxiliary_info_offset);
321  }
322  return update_size(pb, pos);
323 }
324 
326 {
327  int64_t pos = avio_tell(pb);
328  avio_wb32(pb, 0); /* size */
329  ffio_wfourcc(pb, "saiz");
330  avio_wb32(pb, 0); /* version & flags */
331  avio_w8(pb, ctx->use_subsamples ? 0 : AES_CTR_IV_SIZE); /* default size*/
332  avio_wb32(pb, ctx->auxiliary_info_entries); /* entry count */
333  if (ctx->use_subsamples) {
335  }
336  return update_size(pb, pos);
337 }
338 
340 {
341  int64_t auxiliary_info_offset;
342 
343  mov_cenc_write_senc_tag(ctx, pb, &auxiliary_info_offset);
344  mov_cenc_write_saio_tag(pb, auxiliary_info_offset);
345  mov_cenc_write_saiz_tag(ctx, pb);
346 }
347 
349 {
350  int64_t pos = avio_tell(pb);
351  avio_wb32(pb, 0); /* size */
352  ffio_wfourcc(pb, "schi");
353 
354  avio_wb32(pb, 32); /* size */
355  ffio_wfourcc(pb, "tenc");
356  avio_wb32(pb, 0); /* version & flags */
357  avio_wb24(pb, 1); /* is encrypted */
358  avio_w8(pb, AES_CTR_IV_SIZE); /* iv size */
359  avio_write(pb, kid, CENC_KID_SIZE);
360 
361  return update_size(pb, pos);
362 }
363 
365 {
366  int64_t pos = avio_tell(pb);
367  avio_wb32(pb, 0); /* size */
368  ffio_wfourcc(pb, "sinf");
369 
370  /* frma */
371  avio_wb32(pb, 12); /* size */
372  ffio_wfourcc(pb, "frma");
373  avio_wl32(pb, track->tag);
374 
375  /* schm */
376  avio_wb32(pb, 20); /* size */
377  ffio_wfourcc(pb, "schm");
378  avio_wb32(pb, 0); /* version & flags */
379  ffio_wfourcc(pb, "cenc"); /* scheme type*/
380  avio_wb32(pb, 0x10000); /* scheme version */
381 
382  /* schi */
383  mov_cenc_write_schi_tag(pb, kid);
384 
385  return update_size(pb, pos);
386 }
387 
389  int use_subsamples, int bitexact)
390 {
391  int ret;
392 
393  ctx->aes_ctr = av_aes_ctr_alloc();
394  if (!ctx->aes_ctr) {
395  return AVERROR(ENOMEM);
396  }
397 
398  ret = av_aes_ctr_init(ctx->aes_ctr, encryption_key);
399  if (ret != 0) {
400  return ret;
401  }
402 
403  if (!bitexact) {
405  }
406 
407  ctx->use_subsamples = use_subsamples;
408 
409  return 0;
410 }
411 
413 {
414  av_aes_ctr_free(ctx->aes_ctr);
415 }
void avio_wb64(AVIOContext *s, uint64_t val)
Definition: aviobuf.c:440
const char * s
Definition: avisynth_c.h:768
Bytestream IO Context.
Definition: avio.h:147
const uint8_t * ff_avc_find_startcode(const uint8_t *p, const uint8_t *end)
Definition: avc.c:64
int tag
stsd fourcc
Definition: movenc.h:102
static int64_t update_size(AVIOContext *pb, int64_t pos)
Definition: movenccenc.c:282
static int mov_cenc_write_saiz_tag(MOVMuxCencContext *ctx, AVIOContext *pb)
Definition: movenccenc.c:325
size_t auxiliary_info_size
Definition: movenccenc.h:36
struct AVAESCTR * aes_ctr
Definition: movenccenc.h:34
static int mov_cenc_start_packet(MOVMuxCencContext *ctx)
Start writing a packet.
Definition: movenccenc.c:109
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:230
void ff_mov_cenc_free(MOVMuxCencContext *ctx)
Free a CENC context.
Definition: movenccenc.c:412
void av_aes_ctr_increment_iv(struct AVAESCTR *a)
Increment the top 64 bit of the iv (performed after each frame)
Definition: aes_ctr.c:98
static int auxiliary_info_write(MOVMuxCencContext *ctx, const uint8_t *buf_in, int size)
Definition: movenccenc.c:43
int version
Definition: avisynth_c.h:766
uint32_t auxiliary_info_entries
Definition: movenccenc.h:38
int ff_mov_cenc_write_packet(MOVMuxCencContext *ctx, AVIOContext *pb, const uint8_t *buf_in, int size)
Write a fully encrypted packet.
Definition: movenccenc.c:167
Format I/O context.
Definition: avformat.h:1338
static int mov_cenc_write_senc_tag(MOVMuxCencContext *ctx, AVIOContext *pb, int64_t *auxiliary_info_offset)
Definition: movenccenc.c:292
void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src, int count)
Process a buffer using a previously initialized context.
Definition: aes_ctr.c:105
void avio_wl32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:346
uint8_t
static int auxiliary_info_add_subsample(MOVMuxCencContext *ctx, uint16_t clear_bytes, uint32_t encrypted_bytes)
Definition: movenccenc.c:58
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
static int mov_cenc_write_saio_tag(AVIOContext *pb, int64_t auxiliary_info_offset)
Definition: movenccenc.c:306
size_t auxiliary_info_sizes_alloc_size
Definition: movenccenc.h:45
int ff_mov_cenc_init(MOVMuxCencContext *ctx, uint8_t *encryption_key, int use_subsamples, int bitexact)
Initialize a CENC context.
Definition: movenccenc.c:388
ptrdiff_t size
Definition: opengl_enc.c:101
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:511
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:204
static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
Definition: avio_internal.h:66
#define AV_WB16(p, v)
Definition: intreadwrite.h:405
void av_aes_ctr_free(struct AVAESCTR *a)
Release an AVAESCTR context.
Definition: aes_ctr.c:78
#define av_log(a,...)
static void mov_cenc_write_encrypted(MOVMuxCencContext *ctx, AVIOContext *pb, const uint8_t *buf_in, int size)
Encrypt the input buffer and write using avio_write.
Definition: movenccenc.c:89
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
uint16_t subsample_count
Definition: movenccenc.h:42
#define AVERROR(e)
Definition: error.h:43
int ff_mov_cenc_avc_parse_nal_units(MOVMuxCencContext *ctx, AVIOContext *pb, const uint8_t *buf_in, int size)
Parse AVC NAL units from annex B format, the nal size and type are written in the clear while the bod...
Definition: movenccenc.c:192
uint8_t * auxiliary_info
Definition: movenccenc.h:35
#define FFMAX(a, b)
Definition: common.h:94
struct AVAESCTR * av_aes_ctr_alloc(void)
Allocate an AVAESCTR context.
Definition: aes_ctr.c:36
static int auxiliary_info_alloc_size(MOVMuxCencContext *ctx, int size)
Definition: movenccenc.c:27
uint8_t * auxiliary_info_sizes
Definition: movenccenc.h:44
#define FFMIN(a, b)
Definition: common.h:96
void avio_wb24(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:464
AVFormatContext * ctx
Definition: movenc.c:48
int ff_mov_cenc_avc_write_nal_units(AVFormatContext *s, MOVMuxCencContext *ctx, int nal_length_size, AVIOContext *pb, const uint8_t *buf_in, int size)
Write AVC NAL units that are in MP4 format, the nal size and type are written in the clear while the ...
Definition: movenccenc.c:232
void av_aes_ctr_set_random_iv(struct AVAESCTR *a)
Generate a random iv.
Definition: aes_ctr.c:53
static int mov_cenc_write_schi_tag(AVIOContext *pb, uint8_t *kid)
Definition: movenccenc.c:348
int av_reallocp(void *ptr, size_t size)
Allocate, reallocate, or free a block of memory through a pointer to a pointer.
Definition: mem.c:187
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:182
int ff_mov_cenc_write_sinf_tag(MOVTrack *track, AVIOContext *pb, uint8_t *kid)
Write the sinf atom, contained inside stsd.
Definition: movenccenc.c:364
#define AV_WB32(p, v)
Definition: intreadwrite.h:419
size_t auxiliary_info_alloc_size
Definition: movenccenc.h:37
size_t auxiliary_info_subsample_start
Definition: movenccenc.h:43
int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key)
Initialize an AVAESCTR context.
Definition: aes_ctr.c:63
#define CENC_KID_SIZE
Definition: movenccenc.h:29
void avio_wb32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:354
void ff_mov_cenc_write_stbl_atoms(MOVMuxCencContext *ctx, AVIOContext *pb)
Write the cenc atoms that should reside inside stbl.
Definition: movenccenc.c:339
#define AES_CTR_IV_SIZE
Definition: aes_ctr.h:31
static int mov_cenc_end_packet(MOVMuxCencContext *ctx)
Finalize a packet.
Definition: movenccenc.c:137
const uint8_t * av_aes_ctr_get_iv(struct AVAESCTR *a)
Get the current iv.
Definition: aes_ctr.c:48