FFmpeg
movenccenc.c
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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 
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 
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 */
124  ctx->auxiliary_info_subsample_start = ctx->auxiliary_info_size;
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 
141  av_aes_ctr_increment_iv(ctx->aes_ctr);
142 
143  if (!ctx->use_subsamples) {
144  ctx->auxiliary_info_entries++;
145  return 0;
146  }
147 
148  /* add the auxiliary info entry size*/
149  if (ctx->auxiliary_info_entries >= ctx->auxiliary_info_sizes_alloc_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  }
157  ctx->auxiliary_info_sizes[ctx->auxiliary_info_entries] =
158  AES_CTR_IV_SIZE + ctx->auxiliary_info_size - ctx->auxiliary_info_subsample_start;
159  ctx->auxiliary_info_entries++;
160 
161  /* update the subsample count*/
162  AV_WB16(ctx->auxiliary_info + ctx->auxiliary_info_subsample_start, ctx->subsample_count);
163 
164  return 0;
165 }
166 
168  const uint8_t *buf_in, int size)
169 {
170  int ret;
171 
173  if (ret) {
174  return ret;
175  }
176 
178  if (ret) {
179  return ret;
180  }
181 
182  mov_cenc_write_encrypted(ctx, pb, buf_in, size);
183 
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 
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 
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 
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 
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);
302  avio_write(pb, ctx->auxiliary_info, ctx->auxiliary_info_size);
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);
309  uint8_t version;
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) {
334  avio_write(pb, ctx->auxiliary_info_sizes, ctx->auxiliary_info_entries);
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);
346 }
347 
348 static int mov_cenc_write_schi_tag(AVIOContext *pb, uint8_t* kid)
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 
364 int ff_mov_cenc_write_sinf_tag(MOVTrack* track, AVIOContext *pb, uint8_t* kid)
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 
388 int ff_mov_cenc_init(MOVMuxCencContext* ctx, uint8_t* encryption_key,
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) {
404  av_aes_ctr_set_random_iv(ctx->aes_ctr);
405  }
406 
407  ctx->use_subsamples = use_subsamples;
408 
409  return 0;
410 }
411 
413 {
414  av_aes_ctr_free(ctx->aes_ctr);
415  av_freep(&ctx->auxiliary_info);
416  av_freep(&ctx->auxiliary_info_sizes);
417 }
mov_cenc_write_senc_tag
static int mov_cenc_write_senc_tag(MOVMuxCencContext *ctx, AVIOContext *pb, int64_t *auxiliary_info_offset)
Definition: movenccenc.c:292
AVERROR
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
ffio_wfourcc
static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
Definition: avio_internal.h:116
mov_cenc_write_saio_tag
static int mov_cenc_write_saio_tag(AVIOContext *pb, int64_t auxiliary_info_offset)
Definition: movenccenc.c:306
auxiliary_info_alloc_size
static int auxiliary_info_alloc_size(MOVMuxCencContext *ctx, int size)
Definition: movenccenc.c:27
mov_cenc_write_encrypted
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
av_aes_ctr_init
int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key)
Initialize an AVAESCTR context.
Definition: aes_ctr.c:69
MOVTrack::tag
int tag
stsd fourcc
Definition: movenc.h:107
av_aes_ctr_get_iv
const uint8_t * av_aes_ctr_get_iv(struct AVAESCTR *a)
Get the current iv.
Definition: aes_ctr.c:54
mov_cenc_end_packet
static int mov_cenc_end_packet(MOVMuxCencContext *ctx)
Finalize a packet.
Definition: movenccenc.c:137
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
mov_cenc_start_packet
static int mov_cenc_start_packet(MOVMuxCencContext *ctx)
Start writing a packet.
Definition: movenccenc.c:109
AES_CTR_IV_SIZE
#define AES_CTR_IV_SIZE
Definition: aes_ctr.h:30
MOVTrack
Definition: movenc.h:85
av_aes_ctr_alloc
struct AVAESCTR * av_aes_ctr_alloc(void)
Allocate an AVAESCTR context.
Definition: aes_ctr.c:36
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:504
CENC_KID_SIZE
#define CENC_KID_SIZE
Definition: movenccenc.h:29
ff_mov_cenc_free
void ff_mov_cenc_free(MOVMuxCencContext *ctx)
Free a CENC context.
Definition: movenccenc.c:412
mov_cenc_write_schi_tag
static int mov_cenc_write_schi_tag(AVIOContext *pb, uint8_t *kid)
Definition: movenccenc.c:348
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
movenccenc.h
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
update_size
static int64_t update_size(AVIOContext *pb, int64_t pos)
Definition: movenccenc.c:282
av_aes_ctr_crypt
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:111
av_aes_ctr_set_random_iv
void av_aes_ctr_set_random_iv(struct AVAESCTR *a)
Generate a random iv.
Definition: aes_ctr.c:59
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AVFormatContext
Format I/O context.
Definition: avformat.h:1193
AV_WB16
#define AV_WB16(p, v)
Definition: intreadwrite.h:405
ff_mov_cenc_avc_write_nal_units
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
avc.h
avio_w8
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:210
ff_mov_cenc_init
int ff_mov_cenc_init(MOVMuxCencContext *ctx, uint8_t *encryption_key, int use_subsamples, int bitexact)
Initialize a CENC context.
Definition: movenccenc.c:388
movenc.h
AV_WB32
#define AV_WB32(p, v)
Definition: intreadwrite.h:419
av_aes_ctr_free
void av_aes_ctr_free(struct AVAESCTR *a)
Release an AVAESCTR context.
Definition: aes_ctr.c:84
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
mov_cenc_write_saiz_tag
static int mov_cenc_write_saiz_tag(MOVMuxCencContext *ctx, AVIOContext *pb)
Definition: movenccenc.c:325
ff_mov_cenc_write_packet
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
size
int size
Definition: twinvq_data.h:10344
av_reallocp
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:185
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:232
avio_wb32
void avio_wb32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:394
avio_wl32
void avio_wl32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:386
ff_mov_cenc_write_stbl_atoms
void ff_mov_cenc_write_stbl_atoms(MOVMuxCencContext *ctx, AVIOContext *pb)
Write the cenc atoms that should reside inside stbl.
Definition: movenccenc.c:339
version
version
Definition: libkvazaar.c:307
auxiliary_info_write
static int auxiliary_info_write(MOVMuxCencContext *ctx, const uint8_t *buf_in, int size)
Definition: movenccenc.c:43
avio_internal.h
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
ret
ret
Definition: filter_design.txt:187
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:260
ff_mov_cenc_write_sinf_tag
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
auxiliary_info_add_subsample
static int auxiliary_info_add_subsample(MOVMuxCencContext *ctx, uint16_t clear_bytes, uint32_t encrypted_bytes)
Definition: movenccenc.c:58
pos
unsigned int pos
Definition: spdifenc.c:412
avio_wb64
void avio_wb64(AVIOContext *s, uint64_t val)
Definition: aviobuf.c:460
MOVMuxCencContext
Definition: movenccenc.h:33
avio_wb24
void avio_wb24(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:484
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
av_aes_ctr_increment_iv
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:104
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
ff_mov_cenc_avc_parse_nal_units
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
ff_avc_find_startcode
const uint8_t * ff_avc_find_startcode(const uint8_t *p, const uint8_t *end)
Definition: avc.c:67