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asterisk/channels/vcodecs.c

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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright 2007-2008, Sergio Fadda, Luigi Rizzo
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*
* Video codecs support for console_video.c
* $Revision$
*/
#include "asterisk.h"
#include "console_video.h"
#include "asterisk/frame.h"
#include "asterisk/utils.h" /* ast_calloc() */
struct video_out_desc;
struct video_dec_desc;
struct fbuf_t;
/*
* Each codec is defined by a number of callbacks
*/
/*! \brief initialize the encoder */
typedef int (*encoder_init_f)(AVCodecContext *v);
/*! \brief actually call the encoder */
typedef int (*encoder_encode_f)(struct video_out_desc *v);
/*! \brief encapsulate the bistream in RTP frames */
typedef struct ast_frame *(*encoder_encap_f)(struct fbuf_t *, int mtu,
struct ast_frame **tail);
/*! \brief inizialize the decoder */
typedef int (*decoder_init_f)(AVCodecContext *enc_ctx);
/*! \brief extract the bitstream from RTP frames and store in the fbuf.
* return 0 if ok, 1 on error
*/
typedef int (*decoder_decap_f)(struct fbuf_t *b, uint8_t *data, int len);
/*! \brief actually call the decoder */
typedef int (*decoder_decode_f)(struct video_dec_desc *v, struct fbuf_t *b);
struct video_codec_desc {
const char *name; /* format name */
int format; /* AST_FORMAT_* */
encoder_init_f enc_init;
encoder_encap_f enc_encap;
encoder_encode_f enc_run;
decoder_init_f dec_init;
decoder_decap_f dec_decap;
decoder_decode_f dec_run;
};
/*
* Descriptor for the incoming stream, with multiple buffers for the bitstream
* extracted from the RTP packets, RTP reassembly info, and a frame buffer
* for the decoded frame (buf).
* The descriptor is allocated as the first frame comes in.
*
* Incoming payload is stored in one of the dec_in[] buffers, which are
* emptied by the video thread. These buffers are organized in a circular
* queue, with dec_in_cur being the buffer in use by the incoming stream,
* and dec_in_dpy is the one being displayed. When the pointers need to
* be changed, we synchronize the access to them with dec_lock.
* When the list is full dec_in_cur = NULL (we cannot store new data),
* when the list is empty dec_in_dpy = NULL (we cannot display frames).
*/
struct video_dec_desc {
struct video_codec_desc *d_callbacks; /* decoder callbacks */
AVCodecContext *dec_ctx; /* information about the codec in the stream */
AVCodec *codec; /* reference to the codec */
AVFrame *d_frame; /* place to store the decoded frame */
AVCodecParserContext *parser;
uint16_t next_seq; /* must be 16 bit */
int discard; /* flag for discard status */
#define N_DEC_IN 3 /* number of incoming buffers */
struct fbuf_t *dec_in_cur; /* buffer being filled in */
struct fbuf_t *dec_in_dpy; /* buffer to display */
struct fbuf_t dec_in[N_DEC_IN]; /* incoming bitstream, allocated/extended in fbuf_append() */
struct fbuf_t dec_out; /* decoded frame, no buffer (data is in AVFrame) */
};
#ifdef debugging_only
/* some debugging code to check the bitstream:
* declare a bit buffer, initialize it, and fetch data from it.
*/
struct bitbuf {
const uint8_t *base;
int bitsize; /* total size in bits */
int ofs; /* next bit to read */
};
static struct bitbuf bitbuf_init(const uint8_t *base, int bitsize, int start_ofs)
{
struct bitbuf a;
a.base = base;
a.bitsize = bitsize;
a.ofs = start_ofs;
return a;
}
static int bitbuf_left(struct bitbuf *b)
{
return b->bitsize - b->ofs;
}
static uint32_t getbits(struct bitbuf *b, int n)
{
int i, ofs;
const uint8_t *d;
uint8_t mask;
uint32_t retval = 0;
if (n> 31) {
ast_log(LOG_WARNING, "too many bits %d, max 32\n", n);
return 0;
}
if (n + b->ofs > b->bitsize) {
ast_log(LOG_WARNING, "bitbuf overflow %d of %d\n", n + b->ofs, b->bitsize);
n = b->bitsize - b->ofs;
}
ofs = 7 - b->ofs % 8; /* start from msb */
mask = 1 << ofs;
d = b->base + b->ofs / 8; /* current byte */
for (i=0 ; i < n; i++) {
retval += retval + (*d & mask ? 1 : 0); /* shift in new byte */
b->ofs++;
mask >>= 1;
if (mask == 0) {
d++;
mask = 0x80;
}
}
return retval;
}
static void check_h261(struct fbuf_t *b)
{
struct bitbuf a = bitbuf_init(b->data, b->used * 8, 0);
uint32_t x, y;
x = getbits(&a, 20); /* PSC, 0000 0000 0000 0001 0000 */
if (x != 0x10) {
ast_log(LOG_WARNING, "bad PSC 0x%x\n", x);
return;
}
x = getbits(&a, 5); /* temporal reference */
y = getbits(&a, 6); /* ptype */
if (0)
ast_log(LOG_WARNING, "size %d TR %d PTY spl %d doc %d freeze %d %sCIF hi %d\n",
b->used,
x,
(y & 0x20) ? 1 : 0,
(y & 0x10) ? 1 : 0,
(y & 0x8) ? 1 : 0,
(y & 0x4) ? "" : "Q",
(y & 0x2) ? 1:0);
while ( (x = getbits(&a, 1)) == 1)
ast_log(LOG_WARNING, "PSPARE 0x%x\n", getbits(&a, 8));
// ast_log(LOG_WARNING, "PSPARE 0 - start GOB LAYER\n");
while ( (x = bitbuf_left(&a)) > 0) {
// ast_log(LOG_WARNING, "GBSC %d bits left\n", x);
x = getbits(&a, 16); /* GBSC 0000 0000 0000 0001 */
if (x != 0x1) {
ast_log(LOG_WARNING, "bad GBSC 0x%x\n", x);
break;
}
x = getbits(&a, 4); /* group number */
y = getbits(&a, 5); /* gquant */
if (x == 0) {
ast_log(LOG_WARNING, " bad GN %d\n", x);
break;
}
while ( (x = getbits(&a, 1)) == 1)
ast_log(LOG_WARNING, "GSPARE 0x%x\n", getbits(&a, 8));
while ( (x = bitbuf_left(&a)) > 0) { /* MB layer */
break;
}
}
}
void dump_buf(struct fbuf_t *b);
void dump_buf(struct fbuf_t *b)
{
int i, x, last2lines;
char buf[80];
last2lines = (b->used - 16) & ~0xf;
ast_log(LOG_WARNING, "buf size %d of %d\n", b->used, b->size);
for (i = 0; i < b->used; i++) {
x = i & 0xf;
if ( x == 0) { /* new line */
if (i != 0)
ast_log(LOG_WARNING, "%s\n", buf);
memset(buf, '\0', sizeof(buf));
sprintf(buf, "%04x: ", i);
}
sprintf(buf + 6 + x*3, "%02x ", b->data[i]);
if (i > 31 && i < last2lines)
i = last2lines - 1;
}
if (buf[0])
ast_log(LOG_WARNING, "%s\n", buf);
}
#endif /* debugging_only */
/*!
* Build an ast_frame for a given chunk of data, and link it into
* the queue, with possibly 'head' bytes at the beginning to
* fill in some fields later.
*/
static struct ast_frame *create_video_frame(uint8_t *start, uint8_t *end,
int format, int head, struct ast_frame *prev)
{
int len = end-start;
uint8_t *data;
struct ast_frame *f;
data = ast_calloc(1, len+head);
f = ast_calloc(1, sizeof(*f));
if (f == NULL || data == NULL) {
ast_log(LOG_WARNING, "--- frame error f %p data %p len %d format %d\n",
f, data, len, format);
if (f)
ast_free(f);
if (data)
ast_free(data);
return NULL;
}
memcpy(data+head, start, len);
f->data.ptr = data;
f->mallocd = AST_MALLOCD_DATA | AST_MALLOCD_HDR;
//f->has_timing_info = 1;
//f->ts = ast_tvdiff_ms(ast_tvnow(), out->ts);
f->datalen = len+head;
f->frametype = AST_FRAME_VIDEO;
f->subclass = format;
f->samples = 0;
f->offset = 0;
f->src = "Console";
f->delivery.tv_sec = 0;
f->delivery.tv_usec = 0;
f->seqno = 0;
AST_LIST_NEXT(f, frame_list) = NULL;
if (prev)
AST_LIST_NEXT(prev, frame_list) = f;
return f;
}
/*
* Append a chunk of data to a buffer taking care of bit alignment
* Return 0 on success, != 0 on failure
*/
static int fbuf_append(struct fbuf_t *b, uint8_t *src, int len,
int sbit, int ebit)
{
/*
* Allocate buffer. ffmpeg wants an extra FF_INPUT_BUFFER_PADDING_SIZE,
* and also wants 0 as a buffer terminator to prevent trouble.
*/
int need = len + FF_INPUT_BUFFER_PADDING_SIZE;
int i;
uint8_t *dst, mask;
if (b->data == NULL) {
b->size = need;
b->used = 0;
b->ebit = 0;
b->data = ast_calloc(1, b->size);
} else if (b->used + need > b->size) {
b->size = b->used + need;
b->data = ast_realloc(b->data, b->size);
}
if (b->data == NULL) {
ast_log(LOG_WARNING, "alloc failure for %d, discard\n",
b->size);
return 1;
}
if (b->used == 0 && b->ebit != 0) {
ast_log(LOG_WARNING, "ebit not reset at start\n");
b->ebit = 0;
}
dst = b->data + b->used;
i = b->ebit + sbit; /* bits to ignore around */
if (i == 0) { /* easy case, just append */
/* do everything in the common block */
} else if (i == 8) { /* easy too, just handle the overlap byte */
mask = (1 << b->ebit) - 1;
/* update the last byte in the buffer */
dst[-1] &= ~mask; /* clear bits to ignore */
dst[-1] |= (*src & mask); /* append new bits */
src += 1; /* skip and prepare for common block */
len --;
} else { /* must shift the new block, not done yet */
ast_log(LOG_WARNING, "must handle shift %d %d at %d\n",
b->ebit, sbit, b->used);
return 1;
}
memcpy(dst, src, len);
b->used += len;
b->ebit = ebit;
b->data[b->used] = 0; /* padding */
return 0;
}
/*
* Here starts the glue code for the various supported video codecs.
* For each of them, we need to provide routines for initialization,
* calling the encoder, encapsulating the bitstream in ast_frames,
* extracting payload from ast_frames, and calling the decoder.
*/
/*--- h263+ support --- */
/*! \brief initialization of h263p */
static int h263p_enc_init(AVCodecContext *enc_ctx)
{
/* modes supported are
- Unrestricted Motion Vector (annex D)
- Advanced Prediction (annex F)
- Advanced Intra Coding (annex I)
- Deblocking Filter (annex J)
- Slice Structure (annex K)
- Alternative Inter VLC (annex S)
- Modified Quantization (annex T)
*/
enc_ctx->flags |=CODEC_FLAG_H263P_UMV; /* annex D */
enc_ctx->flags |=CODEC_FLAG_AC_PRED; /* annex f ? */
enc_ctx->flags |=CODEC_FLAG_H263P_SLICE_STRUCT; /* annex k */
enc_ctx->flags |= CODEC_FLAG_H263P_AIC; /* annex I */
return 0;
}
/*
* Create RTP/H.263 fragments to avoid IP fragmentation. We fragment on a
* PSC or a GBSC, but if we don't find a suitable place just break somewhere.
* Everything is byte-aligned.
*/
static struct ast_frame *h263p_encap(struct fbuf_t *b, int mtu,
struct ast_frame **tail)
{
struct ast_frame *cur = NULL, *first = NULL;
uint8_t *d = b->data;
int len = b->used;
int l = len; /* size of the current fragment. If 0, must look for a psc */
for (;len > 0; len -= l, d += l) {
uint8_t *data;
struct ast_frame *f;
int i, h;
if (len >= 3 && d[0] == 0 && d[1] == 0 && d[2] >= 0x80) {
/* we are starting a new block, so look for a PSC. */
for (i = 3; i < len - 3; i++) {
if (d[i] == 0 && d[i+1] == 0 && d[i+2] >= 0x80) {
l = i;
break;
}
}
}
if (l > mtu || l > len) { /* psc not found, split */
l = MIN(len, mtu);
}
if (l < 1 || l > mtu) {
ast_log(LOG_WARNING, "--- frame error l %d\n", l);
break;
}
if (d[0] == 0 && d[1] == 0) { /* we start with a psc */
h = 0;
} else { /* no psc, create a header */
h = 2;
}
f = create_video_frame(d, d+l, AST_FORMAT_H263_PLUS, h, cur);
if (!f)
break;
data = f->data.ptr;
if (h == 0) { /* we start with a psc */
data[0] |= 0x04; // set P == 1, and we are done
} else { /* no psc, create a header */
data[0] = data[1] = 0; // P == 0
}
if (!cur)
first = f;
cur = f;
}
if (cur)
cur->subclass |= 1; // RTP Marker
*tail = cur; /* end of the list */
return first;
}
/*! \brief extract the bitstreem from the RTP payload.
* This is format dependent.
* For h263+, the format is defined in RFC 2429
* and basically has a fixed 2-byte header as follows:
* 5 bits RR reserved, shall be 0
* 1 bit P indicate a start/end condition,
* in which case the payload should be prepended
* by two zero-valued bytes.
* 1 bit V there is an additional VRC header after this header
* 6 bits PLEN length in bytes of extra picture header
* 3 bits PEBIT how many bits to be ignored in the last byte
*
* XXX the code below is not complete.
*/
static int h263p_decap(struct fbuf_t *b, uint8_t *data, int len)
{
int PLEN;
if (len < 2) {
ast_log(LOG_WARNING, "invalid framesize %d\n", len);
return 1;
}
PLEN = ( (data[0] & 1) << 5 ) | ( (data[1] & 0xf8) >> 3);
if (PLEN > 0) {
data += PLEN;
len -= PLEN;
}
if (data[0] & 4) /* bit P */
data[0] = data[1] = 0;
else {
data += 2;
len -= 2;
}
return fbuf_append(b, data, len, 0, 0); /* ignore trail bits */
}
/*
* generic encoder, used by the various protocols supported here.
* We assume that the buffer is empty at the beginning.
*/
static int ffmpeg_encode(struct video_out_desc *v)
{
struct fbuf_t *b = &v->enc_out;
int i;
b->used = avcodec_encode_video(v->enc_ctx, b->data, b->size, v->enc_in_frame);
i = avcodec_encode_video(v->enc_ctx, b->data + b->used, b->size - b->used, NULL); /* delayed frames ? */
if (i > 0) {
ast_log(LOG_WARNING, "have %d more bytes\n", i);
b->used += i;
}
return 0;
}
/*
* Generic decoder, which is used by h263p, h263 and h261 as it simply
* invokes ffmpeg's decoder.
* av_parser_parse should merge a randomly chopped up stream into
* proper frames. After that, if we have a valid frame, we decode it
* until the entire frame is processed.
*/
static int ffmpeg_decode(struct video_dec_desc *v, struct fbuf_t *b)
{
uint8_t *src = b->data;
int srclen = b->used;
int full_frame = 0;
if (srclen == 0) /* no data */
return 0;
while (srclen) {
uint8_t *data;
int datalen, ret;
int len = av_parser_parse(v->parser, v->dec_ctx, &data, &datalen, src, srclen, 0, 0);
src += len;
srclen -= len;
/* The parser might return something it cannot decode, so it skips
* the block returning no data
*/
if (data == NULL || datalen == 0)
continue;
ret = avcodec_decode_video(v->dec_ctx, v->d_frame, &full_frame, data, datalen);
if (full_frame == 1) /* full frame */
break;
if (ret < 0) {
ast_log(LOG_NOTICE, "Error decoding\n");
break;
}
}
if (srclen != 0) /* update b with leftover data */
memmove(b->data, src, srclen);
b->used = srclen;
b->ebit = 0;
return full_frame;
}
static struct video_codec_desc h263p_codec = {
.name = "h263p",
.format = AST_FORMAT_H263_PLUS,
.enc_init = h263p_enc_init,
.enc_encap = h263p_encap,
.enc_run = ffmpeg_encode,
.dec_init = NULL,
.dec_decap = h263p_decap,
.dec_run = ffmpeg_decode
};
/*--- Plain h263 support --------*/
static int h263_enc_init(AVCodecContext *enc_ctx)
{
/* XXX check whether these are supported */
enc_ctx->flags |= CODEC_FLAG_H263P_UMV;
enc_ctx->flags |= CODEC_FLAG_H263P_AIC;
enc_ctx->flags |= CODEC_FLAG_H263P_SLICE_STRUCT;
enc_ctx->flags |= CODEC_FLAG_AC_PRED;
return 0;
}
/*
* h263 encapsulation is specified in RFC2190. There are three modes
* defined (A, B, C), with 4, 8 and 12 bytes of header, respectively.
* The header is made as follows
* 0.....................|.......................|.............|....31
* F:1 P:1 SBIT:3 EBIT:3 SRC:3 I:1 U:1 S:1 A:1 R:4 DBQ:2 TRB:3 TR:8
* FP = 0- mode A, (only one word of header)
* FP = 10 mode B, and also means this is an I or P frame
* FP = 11 mode C, and also means this is a PB frame.
* SBIT, EBIT nuber of bits to ignore at beginning (msbits) and end (lsbits)
* SRC bits 6,7,8 from the h263 PTYPE field
* I = 0 intra-coded, 1 = inter-coded (bit 9 from PTYPE)
* U = 1 for Unrestricted Motion Vector (bit 10 from PTYPE)
* S = 1 for Syntax Based Arith coding (bit 11 from PTYPE)
* A = 1 for Advanced Prediction (bit 12 from PTYPE)
* R = reserved, must be 0
* DBQ = differential quantization, DBQUANT from h263, 0 unless we are using
* PB frames
* TRB = temporal reference for bframes, also 0 unless this is a PB frame
* TR = temporal reference for P frames, also 0 unless PB frame.
*
* Mode B and mode C description omitted.
*
* An RTP frame can start with a PSC 0000 0000 0000 0000 1000 0
* or with a GBSC, which also has the first 17 bits as a PSC.
* Note - PSC are byte-aligned, GOB not necessarily. PSC start with
* PSC:22 0000 0000 0000 0000 1000 00 picture start code
* TR:8 .... .... temporal reference
* PTYPE:13 or more ptype...
* If we don't fragment a GOB SBIT and EBIT = 0.
* reference, 8 bit)
*
* The assumption below is that we start with a PSC.
*/
static struct ast_frame *h263_encap(struct fbuf_t *b, int mtu,
struct ast_frame **tail)
{
uint8_t *d = b->data;
int start = 0, i, len = b->used;
struct ast_frame *f, *cur = NULL, *first = NULL;
const int pheader_len = 4; /* Use RFC-2190 Mode A */
uint8_t h263_hdr[12]; /* worst case, room for a type c header */
uint8_t *h = h263_hdr; /* shorthand */
#define H263_MIN_LEN 6
if (len < H263_MIN_LEN) /* unreasonably small */
return NULL;
memset(h263_hdr, '\0', sizeof(h263_hdr));
/* Now set the header bytes. Only type A by now,
* and h[0] = h[2] = h[3] = 0 by default.
* PTYPE starts 30 bits in the picture, so the first useful
* bit for us is bit 36 i.e. within d[4] (0 is the msbit).
* SRC = d[4] & 0x1c goes into data[1] & 0xe0
* I = d[4] & 0x02 goes into data[1] & 0x10
* U = d[4] & 0x01 goes into data[1] & 0x08
* S = d[5] & 0x80 goes into data[1] & 0x04
* A = d[5] & 0x40 goes into data[1] & 0x02
* R = 0 goes into data[1] & 0x01
* Optimizing it, we have
*/
h[1] = ( (d[4] & 0x1f) << 3 ) | /* SRC, I, U */
( (d[5] & 0xc0) >> 5 ); /* S, A, R */
/* now look for the next PSC or GOB header. First try to hit
* a '0' byte then look around for the 0000 0000 0000 0000 1 pattern
* which is both in the PSC and the GBSC.
*/
for (i = H263_MIN_LEN, start = 0; start < len; start = i, i += 3) {
//ast_log(LOG_WARNING, "search at %d of %d/%d\n", i, start, len);
for (; i < len ; i++) {
uint8_t x, rpos, lpos;
int rpos_i; /* index corresponding to rpos */
if (d[i] != 0) /* cannot be in a GBSC */
continue;
if (i > len - 1)
break;
x = d[i+1];
if (x == 0) /* next is equally good */
continue;
/* see if around us we can make 16 '0' bits for the GBSC.
* Look for the first bit set on the right, and then
* see if we have enough 0 on the left.
* We are guaranteed to end before rpos == 0
*/
for (rpos = 0x80, rpos_i = 8; rpos; rpos >>= 1, rpos_i--)
if (x & rpos) /* found the '1' bit in GBSC */
break;
x = d[i-1]; /* now look behind */
for (lpos = rpos; lpos ; lpos >>= 1)
if (x & lpos) /* too early, not a GBSC */
break;
if (lpos) /* as i said... */
continue;
/* now we have a GBSC starting somewhere in d[i-1],
* but it might be not byte-aligned
*/
if (rpos == 0x80) { /* lucky case */
i = i - 1;
} else { /* XXX to be completed */
ast_log(LOG_WARNING, "unaligned GBSC 0x%x %d\n",
rpos, rpos_i);
}
break;
}
/* This frame is up to offset i (not inclusive).
* We do not split it yet even if larger than MTU.
*/
f = create_video_frame(d + start, d+i, AST_FORMAT_H263,
pheader_len, cur);
if (!f)
break;
memmove(f->data.ptr, h, 4); /* copy the h263 header */
/* XXX to do: if not aligned, fix sbit and ebit,
* then move i back by 1 for the next frame
*/
if (!cur)
first = f;
cur = f;
}
if (cur)
cur->subclass |= 1; // RTP Marker
*tail = cur;
return first;
}
/* XXX We only drop the header here, but maybe we need more. */
static int h263_decap(struct fbuf_t *b, uint8_t *data, int len)
{
if (len < 4) {
ast_log(LOG_WARNING, "invalid framesize %d\n", len);
return 1; /* error */
}
if ( (data[0] & 0x80) == 0) {
len -= 4;
data += 4;
} else {
ast_log(LOG_WARNING, "unsupported mode 0x%x\n",
data[0]);
return 1;
}
return fbuf_append(b, data, len, 0, 0); /* XXX no bit alignment support yet */
}
static struct video_codec_desc h263_codec = {
.name = "h263",
.format = AST_FORMAT_H263,
.enc_init = h263_enc_init,
.enc_encap = h263_encap,
.enc_run = ffmpeg_encode,
.dec_init = NULL,
.dec_decap = h263_decap,
.dec_run = ffmpeg_decode
};
/*---- h261 support -----*/
static int h261_enc_init(AVCodecContext *enc_ctx)
{
/* It is important to set rtp_payload_size = 0, otherwise
* ffmpeg in h261 mode will produce output that it cannot parse.
* Also try to send I frames more frequently than with other codecs.
*/
enc_ctx->rtp_payload_size = 0; /* important - ffmpeg fails otherwise */
return 0;
}
/*
* The encapsulation of H261 is defined in RFC4587 which obsoletes RFC2032
* The bitstream is preceded by a 32-bit header word:
* SBIT:3 EBIT:3 I:1 V:1 GOBN:4 MBAP:5 QUANT:5 HMVD:5 VMVD:5
* SBIT and EBIT are the bits to be ignored at beginning and end,
* I=1 if the stream has only INTRA frames - cannot change during the stream.
* V=0 if motion vector is not used. Cannot change.
* GOBN is the GOB number in effect at the start of packet, 0 if we
* start with a GOB header
* QUANT is the quantizer in effect, 0 if we start with GOB header
* HMVD reference horizontal motion vector. 10000 is forbidden
* VMVD reference vertical motion vector, as above.
* Packetization should occur at GOB boundaries, and if not possible
* with MacroBlock fragmentation. However it is likely that blocks
* are not bit-aligned so we must take care of this.
*/
static struct ast_frame *h261_encap(struct fbuf_t *b, int mtu,
struct ast_frame **tail)
{
uint8_t *d = b->data;
int start = 0, i, len = b->used;
struct ast_frame *f, *cur = NULL, *first = NULL;
const int pheader_len = 4;
uint8_t h261_hdr[4];
uint8_t *h = h261_hdr; /* shorthand */
int sbit = 0, ebit = 0;
#define H261_MIN_LEN 10
if (len < H261_MIN_LEN) /* unreasonably small */
return NULL;
memset(h261_hdr, '\0', sizeof(h261_hdr));
/* Similar to the code in h263_encap, but the marker there is longer.
* Start a few bytes within the bitstream to avoid hitting the marker
* twice. Note we might access the buffer at len, but this is ok because
* the caller has it oversized.
*/
for (i = H261_MIN_LEN, start = 0; start < len - 1; start = i, i += 4) {
#if 0 /* test - disable packetization */
i = len; /* wrong... */
#else
int found = 0, found_ebit = 0; /* last GBSC position found */
for (; i < len ; i++) {
uint8_t x, rpos, lpos;
if (d[i] != 0) /* cannot be in a GBSC */
continue;
x = d[i+1];
if (x == 0) /* next is equally good */
continue;
/* See if around us we find 15 '0' bits for the GBSC.
* Look for the first bit set on the right, and then
* see if we have enough 0 on the left.
* We are guaranteed to end before rpos == 0
*/
for (rpos = 0x80, ebit = 7; rpos; ebit--, rpos >>= 1)
if (x & rpos) /* found the '1' bit in GBSC */
break;
x = d[i-1]; /* now look behind */
for (lpos = (rpos >> 1); lpos ; lpos >>= 1)
if (x & lpos) /* too early, not a GBSC */
break;
if (lpos) /* as i said... */
continue;
/* now we have a GBSC starting somewhere in d[i-1],
* but it might be not byte-aligned. Just remember it.
*/
if (i - start > mtu) /* too large, stop now */
break;
found_ebit = ebit;
found = i;
i += 4; /* continue forward */
}
if (i >= len) { /* trim if we went too forward */
i = len;
ebit = 0; /* hopefully... should ask the bitstream ? */
}
if (i - start > mtu && found) {
/* use the previous GBSC, hope is within the mtu */
i = found;
ebit = found_ebit;
}
#endif /* test */
if (i - start < 4) /* XXX too short ? */
continue;
/* This frame is up to offset i (not inclusive).
* We do not split it yet even if larger than MTU.
*/
f = create_video_frame(d + start, d+i, AST_FORMAT_H261,
pheader_len, cur);
if (!f)
break;
/* recompute header with I=0, V=1 */
h[0] = ( (sbit & 7) << 5 ) | ( (ebit & 7) << 2 ) | 1;
memmove(f->data.ptr, h, 4); /* copy the h261 header */
if (ebit) /* not aligned, restart from previous byte */
i--;
sbit = (8 - ebit) & 7;
ebit = 0;
if (!cur)
first = f;
cur = f;
}
if (cur)
cur->subclass |= 1; // RTP Marker
*tail = cur;
return first;
}
/*
* Pieces might be unaligned so we really need to put them together.
*/
static int h261_decap(struct fbuf_t *b, uint8_t *data, int len)
{
int ebit, sbit;
if (len < 8) {
ast_log(LOG_WARNING, "invalid framesize %d\n", len);
return 1;
}
sbit = (data[0] >> 5) & 7;
ebit = (data[0] >> 2) & 7;
len -= 4;
data += 4;
return fbuf_append(b, data, len, sbit, ebit);
}
static struct video_codec_desc h261_codec = {
.name = "h261",
.format = AST_FORMAT_H261,
.enc_init = h261_enc_init,
.enc_encap = h261_encap,
.enc_run = ffmpeg_encode,
.dec_init = NULL,
.dec_decap = h261_decap,
.dec_run = ffmpeg_decode
};
/* mpeg4 support */
static int mpeg4_enc_init(AVCodecContext *enc_ctx)
{
#if 0
//enc_ctx->flags |= CODEC_FLAG_LOW_DELAY; /*don't use b frames ?*/
enc_ctx->flags |= CODEC_FLAG_AC_PRED;
enc_ctx->flags |= CODEC_FLAG_H263P_UMV;
enc_ctx->flags |= CODEC_FLAG_QPEL;
enc_ctx->flags |= CODEC_FLAG_4MV;
enc_ctx->flags |= CODEC_FLAG_GMC;
enc_ctx->flags |= CODEC_FLAG_LOOP_FILTER;
enc_ctx->flags |= CODEC_FLAG_H263P_SLICE_STRUCT;
#endif
enc_ctx->rtp_payload_size = 0; /* important - ffmpeg fails otherwise */
return 0;
}
/* simplistic encapsulation - just split frames in mtu-size units */
static struct ast_frame *mpeg4_encap(struct fbuf_t *b, int mtu,
struct ast_frame **tail)
{
struct ast_frame *f, *cur = NULL, *first = NULL;
uint8_t *d = b->data;
uint8_t *end = d + b->used;
int len;
for (;d < end; d += len, cur = f) {
len = MIN(mtu, end - d);
f = create_video_frame(d, d + len, AST_FORMAT_MP4_VIDEO, 0, cur);
if (!f)
break;
if (!first)
first = f;
}
if (cur)
cur->subclass |= 1;
*tail = cur;
return first;
}
static int mpeg4_decap(struct fbuf_t *b, uint8_t *data, int len)
{
return fbuf_append(b, data, len, 0, 0);
}
static int mpeg4_decode(struct video_dec_desc *v, struct fbuf_t *b)
{
int full_frame = 0, datalen = b->used;
int ret = avcodec_decode_video(v->dec_ctx, v->d_frame, &full_frame,
b->data, datalen);
if (ret < 0) {
ast_log(LOG_NOTICE, "Error decoding\n");
ret = datalen; /* assume we used everything. */
}
datalen -= ret;
if (datalen > 0) /* update b with leftover bytes */
memmove(b->data, b->data + ret, datalen);
b->used = datalen;
b->ebit = 0;
return full_frame;
}
static struct video_codec_desc mpeg4_codec = {
.name = "mpeg4",
.format = AST_FORMAT_MP4_VIDEO,
.enc_init = mpeg4_enc_init,
.enc_encap = mpeg4_encap,
.enc_run = ffmpeg_encode,
.dec_init = NULL,
.dec_decap = mpeg4_decap,
.dec_run = mpeg4_decode
};
static int h264_enc_init(AVCodecContext *enc_ctx)
{
enc_ctx->flags |= CODEC_FLAG_TRUNCATED;
//enc_ctx->flags |= CODEC_FLAG_GLOBAL_HEADER;
//enc_ctx->flags2 |= CODEC_FLAG2_FASTPSKIP;
/* TODO: Maybe we need to add some other flags */
enc_ctx->rtp_mode = 0;
enc_ctx->rtp_payload_size = 0;
enc_ctx->bit_rate_tolerance = enc_ctx->bit_rate;
return 0;
}
static int h264_dec_init(AVCodecContext *dec_ctx)
{
dec_ctx->flags |= CODEC_FLAG_TRUNCATED;
return 0;
}
/*
* The structure of a generic H.264 stream is:
* - 0..n 0-byte(s), unused, optional. one zero-byte is always present
* in the first NAL before the start code prefix.
* - start code prefix (3 bytes): 0x000001
* (the first bytestream has a
* like these 0x00000001!)
* - NAL header byte ( F[1] | NRI[2] | Type[5] ) where type != 0
* - byte-stream
* - 0..n 0-byte(s) (padding, unused).
* Segmentation in RTP only needs to be done on start code prefixes.
* If fragments are too long... we don't support it yet.
* - encapsulate (or fragment) the byte-stream (with NAL header included)
*/
static struct ast_frame *h264_encap(struct fbuf_t *b, int mtu,
struct ast_frame **tail)
{
struct ast_frame *f = NULL, *cur = NULL, *first = NULL;
uint8_t *d, *start = b->data;
uint8_t *end = start + b->used;
/* Search the first start code prefix - ITU-T H.264 sec. B.2,
* and move start right after that, on the NAL header byte.
*/
#define HAVE_NAL(x) (x[-4] == 0 && x[-3] == 0 && x[-2] == 0 && x[-1] == 1)
for (start += 4; start < end; start++) {
int ty = start[0] & 0x1f;
if (HAVE_NAL(start) && ty != 0 && ty != 31)
break;
}
/* if not found, or too short, we just skip the next loop and are done. */
/* Here follows the main loop to create frames. Search subsequent start
* codes, and then possibly fragment the unit into smaller fragments.
*/
for (;start < end - 4; start = d) {
int size; /* size of current block */
uint8_t hdr[2]; /* add-on header when fragmenting */
int ty = 0;
/* now search next nal */
for (d = start + 4; d < end; d++) {
ty = d[0] & 0x1f;
if (HAVE_NAL(d))
break; /* found NAL */
}
/* have a block to send. d past the start code unless we overflow */
if (d >= end) { /* NAL not found */
d = end + 4;
} else if (ty == 0 || ty == 31) { /* found but invalid type, skip */
ast_log(LOG_WARNING, "skip invalid nal type %d at %d of %d\n",
ty, d - (uint8_t *)b->data, b->used);
continue;
}
size = d - start - 4; /* don't count the end */
if (size < mtu) { // test - don't fragment
// Single NAL Unit
f = create_video_frame(start, d - 4, AST_FORMAT_H264, 0, cur);
if (!f)
break;
if (!first)
first = f;
cur = f;
continue;
}
// Fragmented Unit (Mode A: no DON, very weak)
hdr[0] = (*start & 0xe0) | 28; /* mark as a fragmentation unit */
hdr[1] = (*start++ & 0x1f) | 0x80 ; /* keep type and set START bit */
size--; /* skip the NAL header */
while (size) {
uint8_t *data;
int frag_size = MIN(size, mtu);
f = create_video_frame(start, start+frag_size, AST_FORMAT_H264, 2, cur);
if (!f)
break;
size -= frag_size; /* skip this data block */
start += frag_size;
data = f->data.ptr;
data[0] = hdr[0];
data[1] = hdr[1] | (size == 0 ? 0x40 : 0); /* end bit if we are done */
hdr[1] &= ~0x80; /* clear start bit for subsequent frames */
if (!first)
first = f;
cur = f;
}
}
if (cur)
cur->subclass |= 1; // RTP Marker
*tail = cur;
return first;
}
static int h264_decap(struct fbuf_t *b, uint8_t *data, int len)
{
/* Start Code Prefix (Annex B in specification) */
uint8_t scp[] = { 0x00, 0x00, 0x00, 0x01 };
int retval = 0;
int type, ofs = 0;
if (len < 2) {
ast_log(LOG_WARNING, "--- invalid len %d\n", len);
return 1;
}
/* first of all, check if the packet has F == 0 */
if (data[0] & 0x80) {
ast_log(LOG_WARNING, "--- forbidden packet; nal: %02x\n",
data[0]);
return 1;
}
type = data[0] & 0x1f;
switch (type) {
case 0:
case 31:
ast_log(LOG_WARNING, "--- invalid type: %d\n", type);
return 1;
case 24:
case 25:
case 26:
case 27:
case 29:
ast_log(LOG_WARNING, "--- encapsulation not supported : %d\n", type);
return 1;
case 28: /* FU-A Unit */
if (data[1] & 0x80) { // S == 1, import F and NRI from next
data[1] &= 0x1f; /* preserve type */
data[1] |= (data[0] & 0xe0); /* import F & NRI */
retval = fbuf_append(b, scp, sizeof(scp), 0, 0);
ofs = 1;
} else {
ofs = 2;
}
break;
default: /* From 1 to 23 (Single NAL Unit) */
retval = fbuf_append(b, scp, sizeof(scp), 0, 0);
}
if (!retval)
retval = fbuf_append(b, data + ofs, len - ofs, 0, 0);
if (retval)
ast_log(LOG_WARNING, "result %d\n", retval);
return retval;
}
static struct video_codec_desc h264_codec = {
.name = "h264",
.format = AST_FORMAT_H264,
.enc_init = h264_enc_init,
.enc_encap = h264_encap,
.enc_run = ffmpeg_encode,
.dec_init = h264_dec_init,
.dec_decap = h264_decap,
.dec_run = ffmpeg_decode
};
/*
* Table of translation between asterisk and ffmpeg formats.
* We need also a field for read and write (encoding and decoding), because
* e.g. H263+ uses different codec IDs in ffmpeg when encoding or decoding.
*/
struct _cm { /* map ffmpeg codec types to asterisk formats */
uint32_t ast_format; /* 0 is a terminator */
enum CodecID codec;
enum { CM_RD = 1, CM_WR = 2, CM_RDWR = 3 } rw; /* read or write or both ? */
//struct video_codec_desc *codec_desc;
};
static const struct _cm video_formats[] = {
{ AST_FORMAT_H263_PLUS, CODEC_ID_H263, CM_RD }, /* incoming H263P ? */
{ AST_FORMAT_H263_PLUS, CODEC_ID_H263P, CM_WR },
{ AST_FORMAT_H263, CODEC_ID_H263, CM_RD },
{ AST_FORMAT_H263, CODEC_ID_H263, CM_WR },
{ AST_FORMAT_H261, CODEC_ID_H261, CM_RDWR },
{ AST_FORMAT_H264, CODEC_ID_H264, CM_RDWR },
{ AST_FORMAT_MP4_VIDEO, CODEC_ID_MPEG4, CM_RDWR },
{ 0, 0, 0 },
};
/*! \brief map an asterisk format into an ffmpeg one */
static enum CodecID map_video_format(uint32_t ast_format, int rw)
{
struct _cm *i;
for (i = video_formats; i->ast_format != 0; i++)
if (ast_format & i->ast_format && rw & i->rw && rw & i->rw)
return i->codec;
return CODEC_ID_NONE;
}
/* pointers to supported codecs. We assume the first one to be non null. */
static const struct video_codec_desc *supported_codecs[] = {
&h263p_codec,
&h264_codec,
&h263_codec,
&h261_codec,
&mpeg4_codec,
NULL
};
/*
* Map the AST_FORMAT to the library. If not recognised, fail.
* This is useful in the input path where we get frames.
*/
static struct video_codec_desc *map_video_codec(int fmt)
{
int i;
for (i = 0; supported_codecs[i]; i++)
if (fmt == supported_codecs[i]->format) {
ast_log(LOG_WARNING, "using %s for format 0x%x\n",
supported_codecs[i]->name, fmt);
return supported_codecs[i];
}
return NULL;
}
/*! \brief uninitialize the descriptor for remote video stream */
static struct video_dec_desc *dec_uninit(struct video_dec_desc *v)
{
int i;
if (v == NULL) /* not initialized yet */
return NULL;
if (v->parser) {
av_parser_close(v->parser);
v->parser = NULL;
}
if (v->dec_ctx) {
avcodec_close(v->dec_ctx);
av_free(v->dec_ctx);
v->dec_ctx = NULL;
}
if (v->d_frame) {
av_free(v->d_frame);
v->d_frame = NULL;
}
v->codec = NULL; /* only a reference */
v->d_callbacks = NULL; /* forget the decoder */
v->discard = 1; /* start in discard mode */
for (i = 0; i < N_DEC_IN; i++)
fbuf_free(&v->dec_in[i]);
fbuf_free(&v->dec_out);
ast_free(v);
return NULL; /* error, in case someone cares */
}
/*
* initialize ffmpeg resources used for decoding frames from the network.
*/
static struct video_dec_desc *dec_init(uint32_t the_ast_format)
{
enum CodecID codec;
struct video_dec_desc *v = ast_calloc(1, sizeof(*v));
if (v == NULL)
return NULL;
v->discard = 1;
v->d_callbacks = map_video_codec(the_ast_format);
if (v->d_callbacks == NULL) {
ast_log(LOG_WARNING, "cannot find video codec, drop input 0x%x\n", the_ast_format);
return dec_uninit(v);
}
codec = map_video_format(v->d_callbacks->format, CM_RD);
v->codec = avcodec_find_decoder(codec);
if (!v->codec) {
ast_log(LOG_WARNING, "Unable to find the decoder for format %d\n", codec);
return dec_uninit(v);
}
/*
* Initialize the codec context.
*/
v->dec_ctx = avcodec_alloc_context();
if (!v->dec_ctx) {
ast_log(LOG_WARNING, "Cannot allocate the decoder context\n");
return dec_uninit(v);
}
/* XXX call dec_init() ? */
if (avcodec_open(v->dec_ctx, v->codec) < 0) {
ast_log(LOG_WARNING, "Cannot open the decoder context\n");
av_free(v->dec_ctx);
v->dec_ctx = NULL;
return dec_uninit(v);
}
v->parser = av_parser_init(codec);
if (!v->parser) {
ast_log(LOG_WARNING, "Cannot initialize the decoder parser\n");
return dec_uninit(v);
}
v->d_frame = avcodec_alloc_frame();
if (!v->d_frame) {
ast_log(LOG_WARNING, "Cannot allocate decoding video frame\n");
return dec_uninit(v);
}
v->dec_in_cur = &v->dec_in[0]; /* buffer for incoming frames */
v->dec_in_dpy = NULL; /* nothing to display */
return v; /* ok */
}
/*------ end codec specific code -----*/
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