FFmpeg
avio_http_serve_files.c
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1 /*
2  * Copyright (c) 2015 Stephan Holljes
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a copy
5  * of this software and associated documentation files (the "Software"), to deal
6  * in the Software without restriction, including without limitation the rights
7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8  * copies of the Software, and to permit persons to whom the Software is
9  * furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  * THE SOFTWARE.
21  */
22 
23 /**
24  * @file libavformat multi-client network API usage example
25  * @example avio_http_serve_files.c
26  *
27  * Serve a file without decoding or demuxing it over the HTTP protocol. Multiple
28  * clients can connect and will receive the same file.
29  */
30 
31 #include <libavformat/avformat.h>
32 #include <libavutil/opt.h>
33 #include <unistd.h>
34 
35 static void process_client(AVIOContext *client, const char *in_uri)
36 {
38  uint8_t buf[1024];
39  int ret, n, reply_code;
40  uint8_t *resource = NULL;
41  while ((ret = avio_handshake(client)) > 0) {
42  av_opt_get(client, "resource", AV_OPT_SEARCH_CHILDREN, &resource);
43  // check for strlen(resource) is necessary, because av_opt_get()
44  // may return empty string.
45  if (resource && strlen(resource))
46  break;
47  av_freep(&resource);
48  }
49  if (ret < 0)
50  goto end;
51  av_log(client, AV_LOG_TRACE, "resource=%p\n", resource);
52  if (resource && resource[0] == '/' && !strcmp((resource + 1), in_uri)) {
53  reply_code = 200;
54  } else {
55  reply_code = AVERROR_HTTP_NOT_FOUND;
56  }
57  if ((ret = av_opt_set_int(client, "reply_code", reply_code, AV_OPT_SEARCH_CHILDREN)) < 0) {
58  av_log(client, AV_LOG_ERROR, "Failed to set reply_code: %s.\n", av_err2str(ret));
59  goto end;
60  }
61  av_log(client, AV_LOG_TRACE, "Set reply code to %d\n", reply_code);
62 
63  while ((ret = avio_handshake(client)) > 0);
64 
65  if (ret < 0)
66  goto end;
67 
68  fprintf(stderr, "Handshake performed.\n");
69  if (reply_code != 200)
70  goto end;
71  fprintf(stderr, "Opening input file.\n");
72  if ((ret = avio_open2(&input, in_uri, AVIO_FLAG_READ, NULL, NULL)) < 0) {
73  av_log(input, AV_LOG_ERROR, "Failed to open input: %s: %s.\n", in_uri,
74  av_err2str(ret));
75  goto end;
76  }
77  for(;;) {
78  n = avio_read(input, buf, sizeof(buf));
79  if (n < 0) {
80  if (n == AVERROR_EOF)
81  break;
82  av_log(input, AV_LOG_ERROR, "Error reading from input: %s.\n",
83  av_err2str(n));
84  break;
85  }
86  avio_write(client, buf, n);
87  avio_flush(client);
88  }
89 end:
90  fprintf(stderr, "Flushing client\n");
91  avio_flush(client);
92  fprintf(stderr, "Closing client\n");
93  avio_close(client);
94  fprintf(stderr, "Closing input\n");
96  av_freep(&resource);
97 }
98 
99 int main(int argc, char **argv)
100 {
102  AVIOContext *client = NULL, *server = NULL;
103  const char *in_uri, *out_uri;
104  int ret, pid;
106  if (argc < 3) {
107  printf("usage: %s input http://hostname[:port]\n"
108  "API example program to serve http to multiple clients.\n"
109  "\n", argv[0]);
110  return 1;
111  }
112 
113  in_uri = argv[1];
114  out_uri = argv[2];
115 
117 
118  if ((ret = av_dict_set(&options, "listen", "2", 0)) < 0) {
119  fprintf(stderr, "Failed to set listen mode for server: %s\n", av_err2str(ret));
120  return ret;
121  }
122  if ((ret = avio_open2(&server, out_uri, AVIO_FLAG_WRITE, NULL, &options)) < 0) {
123  fprintf(stderr, "Failed to open server: %s\n", av_err2str(ret));
124  return ret;
125  }
126  fprintf(stderr, "Entering main loop.\n");
127  for(;;) {
128  if ((ret = avio_accept(server, &client)) < 0)
129  goto end;
130  fprintf(stderr, "Accepted client, forking process.\n");
131  // XXX: Since we don't reap our children and don't ignore signals
132  // this produces zombie processes.
133  pid = fork();
134  if (pid < 0) {
135  perror("Fork failed");
136  ret = AVERROR(errno);
137  goto end;
138  }
139  if (pid == 0) {
140  fprintf(stderr, "In child.\n");
141  process_client(client, in_uri);
142  avio_close(server);
143  exit(0);
144  }
145  if (pid > 0)
146  avio_close(client);
147  }
148 end:
149  avio_close(server);
150  if (ret < 0 && ret != AVERROR_EOF) {
151  fprintf(stderr, "Some errors occurred: %s\n", av_err2str(ret));
152  return 1;
153  }
154  return 0;
155 }
error
static void error(const char *err)
Definition: target_bsf_fuzzer.c:31
M
#define M(a, b)
Definition: vp3dsp.c:48
generate
static av_always_inline void generate(int8_t *out, int out_stride, const uint8_t *in, int in_stride, H274FilmGrainDatabase *database, const AVFilmGrainH274Params *h274, int c, int invert, int deblock, int y_offset, int x_offset)
Definition: h274.c:156
be
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it be(in the first position) for now. Options ------- Then comes the options array. This is what will define the user accessible options. For example
Channel
Definition: aptx.h:81
process
static void process(NormalizeContext *s, AVFrame *in, AVFrame *out)
Definition: vf_normalize.c:154
W
@ W
Definition: vf_addroi.c:27
name
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option name
Definition: writing_filters.txt:88
program
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C program
Definition: undefined.txt:6
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
errors
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object which then gets compiled Helps in developing those assembler files DESTDIR Destination directory for the install useful to prepare packages or install FFmpeg in cross environments GEN Set to ‘1’ to generate the missing or mismatched references Makefile builds all the libraries and the executables fate Run the fate test note that you must have installed it fate list List all fate regression test targets install Install libraries and programs examples Build all examples located in doc examples checkheaders Check headers dependencies alltools Build all tools in tools directory config Reconfigure the project with the current configuration tools target_dec_< decoder > _fuzzer Build fuzzer to fuzz the specified decoder tools target_bsf_< filter > _fuzzer Build fuzzer to fuzz the specified bitstream filter Useful standard make this is useful to reduce unneeded rebuilding when changing but note that you must force rebuilds of files that actually need it by hand then make j< num > Rebuild with multiple jobs at the same time Faster on multi processor systems make k Continue build in case of errors
Definition: build_system.txt:64
opt.h
space
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated space
Definition: undefined.txt:4
avio_close
int avio_close(AVIOContext *s)
Close the resource accessed by the AVIOContext s and free it.
Definition: aviobuf.c:1335
out
FILE * out
Definition: movenc.c:54
is
The official guide to swscale for confused that is
Definition: swscale.txt:28
message
Definition: api-threadmessage-test.c:46
exchange
static int exchange(MqcState *mqc, uint8_t *cxstate, int lps)
Definition: mqcdec.c:45
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
output
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce output
Definition: filter_design.txt:225
w
uint8_t w
Definition: llviddspenc.c:38
targets
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object which then gets compiled Helps in developing those assembler files DESTDIR Destination directory for the install targets
Definition: build_system.txt:16
b
#define b
Definition: input.c:41
table
static const uint16_t table[]
Definition: prosumer.c:205
data
const char data[16]
Definition: mxf.c:148
test
Definition: idctdsp.c:35
possible
the frame and frame reference mechanism is intended to as much as possible
Definition: filter_design.txt:45
F
#define F(x)
process_client
static void process_client(AVIOContext *client, const char *in_uri)
Definition: avio_http_serve_files.c:35
filter
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce then the filter should push the output frames on the output link immediately As an exception to the previous rule if the input frame is enough to produce several output frames then the filter needs output only at least one per link The additional frames can be left buffered in the filter
Definition: filter_design.txt:228
AVDictionary
Definition: dict.c:34
avio_handshake
int avio_handshake(AVIOContext *c)
Perform one step of the protocol handshake to accept a new client.
Definition: aviobuf.c:1464
some
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that some(invalid) inputs can trigger overflows(undefined behavior). In these cases
decoder
static const chunk_decoder decoder[8]
Definition: dfa.c:331
avio_open2
int avio_open2(AVIOContext **s, const char *url, int flags, const AVIOInterruptCB *int_cb, AVDictionary **options)
Create and initialize a AVIOContext for accessing the resource indicated by url.
Definition: aviobuf.c:1329
state
static struct @377 state
type
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf type
Definition: writing_filters.txt:86
ss
#define ss(width, name, subs,...)
Definition: cbs_vp9.c:202
avformat_network_init
int avformat_network_init(void)
Do global initialization of network libraries.
Definition: utils.c:558
variables
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile variables
Definition: build_system.txt:7
AV_LOG_TRACE
#define AV_LOG_TRACE
Extremely verbose debugging, useful for libav* development.
Definition: log.h:206
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
AVERROR_HTTP_NOT_FOUND
#define AVERROR_HTTP_NOT_FOUND
Definition: error.h:81
format
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 format(the sample packing is implied by the sample format) and sample rate. The lists are not just lists
to
const char * to
Definition: webvttdec.c:35
AVIO_FLAG_WRITE
#define AVIO_FLAG_WRITE
write-only
Definition: avio.h:637
B
#define B
Definition: huffyuv.h:42
on
s EdgeDetect Foobar g libavfilter vf_edgedetect c libavfilter vf_foobar c edit libavfilter and add an entry for foobar following the pattern of the other filters edit libavfilter allfilters and add an entry for foobar following the pattern of the other filters configure make j< whatever > ffmpeg ffmpeg i you should get a foobar png with Lena edge detected That s your new playground is ready Some little details about what s going on
Definition: writing_filters.txt:34
key
const char * key
Definition: hwcontext_opencl.c:174
command
static int command(AVFilterContext *ctx, const char *cmd, const char *arg, char *res, int res_len, int flags)
Definition: vf_drawtext.c:1191
link
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 link
Definition: filter_design.txt:23
avio_flush
void avio_flush(AVIOContext *s)
Force flushing of buffered data.
Definition: aviobuf.c:270
need
must be printed separately If there s no standard function for printing the type you need
Definition: tablegen.txt:45
NULL
#define NULL
Definition: coverity.c:32
run
uint8_t run
Definition: svq3.c:203
system
FFmpeg currently uses a custom build system
Definition: build_system.txt:1
V
#define V
Definition: avdct.c:30
avio_accept
int avio_accept(AVIOContext *s, AVIOContext **c)
Accept and allocate a client context on a server context.
Definition: aviobuf.c:1453
list
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 list
Definition: filter_design.txt:25
not
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 not
Definition: filter_design.txt:259
seek
static void BS_FUNC() seek(BSCTX *bc, unsigned pos)
Seek to the given bit position.
Definition: bitstream_template.h:399
commands
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object which then gets compiled Helps in developing those assembler files DESTDIR Destination directory for the install useful to prepare packages or install FFmpeg in cross environments GEN Set to ‘1’ to generate the missing or mismatched references Makefile builds all the libraries and the executables fate Run the fate test note that you must have installed it fate list List all fate regression test targets install Install libraries and programs examples Build all examples located in doc examples checkheaders Check headers dependencies alltools Build all tools in tools directory config Reconfigure the project with the current configuration tools target_dec_< decoder > _fuzzer Build fuzzer to fuzz the specified decoder tools target_bsf_< filter > _fuzzer Build fuzzer to fuzz the specified bitstream filter Useful standard make commands
Definition: build_system.txt:56
av_opt_set_int
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:634
suite
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object which then gets compiled Helps in developing those assembler files DESTDIR Destination directory for the install useful to prepare packages or install FFmpeg in cross environments GEN Set to ‘1’ to generate the missing or mismatched references Makefile builds all the libraries and the executables fate Run the fate test suite
Definition: build_system.txt:28
Block
Definition: flashsv2enc.c:70
main
int main(int argc, char **argv)
Definition: avio_http_serve_files.c:99
options
const OptionDef options[]
AVIOContext
Bytestream IO Context.
Definition: avio.h:166
byte
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_WB16 unsigned int_TMPL byte
Definition: bytestream.h:99
av_err2str
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:121
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
Program
Definition: mpegts.c:120
section
Definition: ffprobe.c:216
printf
printf("static const uint8_t my_array[100] = {\n")
range
enum AVColorRange range
Definition: mediacodec_wrapper.c:2646
AV_OPT_SEARCH_CHILDREN
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
Definition: opt.h:563
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:248
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
that
if it could not because there are no more it should return AVERROR_EOF The typical implementation of request_frame for a filter with several inputs will look like that
Definition: filter_design.txt:273
version
version
Definition: libkvazaar.c:321
input
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some input
Definition: filter_design.txt:172
assign
#define assign(var, type, n)
tests
const TestCase tests[]
Definition: fifo_muxer.c:242
av_log_set_level
void av_log_set_level(int level)
Set the log level.
Definition: log.c:447
State
Definition: gemdec.c:58
code
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Definition: filter_design.txt:178
available
if no frame is available
Definition: filter_design.txt:166
Code
One code in hash table.
Definition: lzwenc.c:43
needed
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is needed
Definition: filter_design.txt:212
directory
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object directory
Definition: build_system.txt:12
files
Writing a table generator This documentation is preliminary Parts of the API are not good and should be changed Basic concepts A table generator consists of two files
Definition: tablegen.txt:8
ret
ret
Definition: filter_design.txt:187
currently
The official guide to swscale for confused that consecutive non overlapping rectangles of slice_bottom special converter These generally are unscaled converters of common like for each output line the vertical scaler pulls lines from a ring buffer When the ring buffer does not contain the wanted then it is pulled from the input slice through the input converter and horizontal scaler The result is also stored in the ring buffer to serve future vertical scaler requests When no more output can be generated because lines from a future slice would be then all remaining lines in the current slice are horizontally scaled and put in the ring buffer[This is done for luma and chroma, each with possibly different numbers of lines per picture.] Input to YUV Converter When the input to the main path is not planar bits per component YUV or bit it is converted to planar bit YUV Two sets of converters exist for this currently
Definition: swscale.txt:54
links
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 links
Definition: filter_design.txt:14
avformat.h
left
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2] ... the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so ...,+,-,+,-,+,+,-,+,-,+,... hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32 - hcoeff[1] - hcoeff[2] - ... a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2} an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||......... intra?||||:Block01 :yes no||||:Block02 :....... ..........||||:Block03 ::y DC ::ref index:||||:Block04 ::cb DC ::motion x :||||......... :cr DC ::motion y :||||....... ..........|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------ ------------ ------------|||Y subbands||Cb subbands||Cr subbands||||--- ---||--- ---||--- ---|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------ ------------ ------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction ------------|\ Dequantization ------------------- \||Reference frames|\ IDWT|------- -------|Motion \|||Frame 0||Frame 1||Compensation . OBMC v -------|------- -------|--------------. \------> Frame n output Frame Frame<----------------------------------/|...|------------------- Range Coder:============Binary Range Coder:------------------- The implemented range coder is an adapted version based upon "Range encoding: an algorithm for removing redundancy from a digitised message." by G. N. N. Martin. The symbols encoded by the Snow range coder are bits(0|1). The associated probabilities are not fix but change depending on the symbol mix seen so far. bit seen|new state ---------+----------------------------------------------- 0|256 - state_transition_table[256 - old_state];1|state_transition_table[old_state];state_transition_table={ 0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:------------------------- FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1. the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
Definition: snow.txt:386
power
static float power(float r, float g, float b, float max)
Definition: preserve_color.h:45
buffer
the frame and frame reference mechanism is intended to as much as expensive copies of that data while still allowing the filters to produce correct results The data is stored in buffers represented by AVFrame structures Several references can point to the same frame buffer
Definition: filter_design.txt:49
mode
mode
Definition: ebur128.h:83
headers
FFmpeg currently uses a custom build this text attempts to document some of its obscure features and options Makefile the full command issued by make and its output will be shown on the screen DBG Preprocess x86 external assembler files to a dbg asm file in the object which then gets compiled Helps in developing those assembler files DESTDIR Destination directory for the install useful to prepare packages or install FFmpeg in cross environments GEN Set to ‘1’ to generate the missing or mismatched references Makefile builds all the libraries and the executables fate Run the fate test note that you must have installed it fate list List all fate regression test targets install Install headers
Definition: build_system.txt:34
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:659
L
#define L(x)
Definition: vpx_arith.h:36
note
F H1 F F H1 F F F F H1<-F-------F-------F v v v H2 H3 H2 ^ ^ ^ F-------F-------F-> H1<-F-------F-------F|||||||||F H1 F|||||||||F H1 Funavailable fullpel samples(outside the picture for example) shall be equalto the closest available fullpel sampleSmaller pel interpolation:--------------------------if diag_mc is set then points which lie on a line between 2 vertically, horizontally or diagonally adjacent halfpel points shall be interpolatedlinearly with rounding to nearest and halfway values rounded up.points which lie on 2 diagonals at the same time should only use the onediagonal not containing the fullpel point F--> O q O<--h1-> O q O<--F v \/v \/v O O O O O O O|/|\|q q q q q|/|\|O O O O O O O ^/\ ^/\ ^ h2--> O q O<--h3-> O q O<--h2 v \/v \/v O O O O O O O|\|/|q q q q q|\|/|O O O O O O O ^/\ ^/\ ^ F--> O q O<--h1-> O q O<--Fthe remaining points shall be bilinearly interpolated from theup to 4 surrounding halfpel and fullpel points, again rounding should be tonearest and halfway values rounded upcompliant Snow decoders MUST support 1-1/8 pel luma and 1/2-1/16 pel chromainterpolation at leastOverlapped block motion compensation:-------------------------------------FIXMELL band prediction:===================Each sample in the LL0 subband is predicted by the median of the left, top andleft+top-topleft samples, samples outside the subband shall be considered tobe 0. To reverse this prediction in the decoder apply the following.for(y=0;y< height;y++){ for(x=0;x< width;x++){ sample[y][x]+=median(sample[y-1][x], sample[y][x-1], sample[y-1][x]+sample[y][x-1]-sample[y-1][x-1]);}}sample[-1][ *]=sample[ *][-1]=0;width, height here are the width and height of the LL0 subband not of the finalvideoDequantization:===============FIXMEWavelet Transform:==================Snow supports 2 wavelet transforms, the symmetric biorthogonal 5/3 integertransform and an integer approximation of the symmetric biorthogonal 9/7daubechies wavelet.2D IDWT(inverse discrete wavelet transform) --------------------------------------------The 2D IDWT applies a 2D filter recursively, each time combining the4 lowest frequency subbands into a single subband until only 1 subbandremains.The 2D filter is done by first applying a 1D filter in the vertical directionand then applying it in the horizontal one. --------------- --------------- --------------- ---------------|LL0|HL0|||||||||||||---+---|HL1||L0|H0|HL1||LL1|HL1|||||LH0|HH0|||||||||||||-------+-------|-> L1 H1 LH1 HH1 LH1 HH1 LH1 HH1 note
Definition: snow.txt:555
bad
static int bad(InterplayACMContext *s, unsigned ind, unsigned col)
Definition: interplayacm.c:129
AVIO_FLAG_READ
#define AVIO_FLAG_READ
read-only
Definition: avio.h:636
it
s EdgeDetect Foobar g libavfilter vf_edgedetect c libavfilter vf_foobar c edit libavfilter and add an entry for foobar following the pattern of the other filters edit libavfilter allfilters and add an entry for foobar following the pattern of the other filters configure make j< whatever > ffmpeg ffmpeg i you should get a foobar png with Lena edge detected That s it
Definition: writing_filters.txt:31
project
static float project(float origin_x, float origin_y, float dest_x, float dest_y, float point_x, float point_y, int type)
Definition: vsrc_gradients.c:203
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
av_dict_set
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:88
Stream
Definition: mpegts.c:113
av_opt_get
int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
Definition: opt.c:847
block
The exact code depends on how similar the blocks are and how related they are to the block
Definition: filter_design.txt:207
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
X
@ X
Definition: vf_addroi.c:27